[cctalk] Re: IBM 360

[John Robertson via cctalk]

On 2024/04/09 7:53 p.m., Murray McCullough via cctalk wrote:

I had not realized the IBM 360 was 60 yrs. old this month. I worked on such
a computer in the late 60s in Toronto. What one could do with 8 Kbytes of
ram was remarkable!

Happy computing

Murray 


One of my early summer jobs as a teenager (19?) was at IBM in Toronto - 
stripping old noise reduction foam from card punch machines so they 
could get sandblasted and repainted...also in the very late 60s.


John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Double Density 3.5" Floppy Disks

[John Robertson via cctalk]

On 2024/04/30 10:08 a.m., Anders Nelson via cctalk wrote:

Having grown up with 1.44MB 3.5" floppies, I have a question: is it
possible to use a 1.44MB disk and just format it as a 720K disk?

=]
--
Anders Nelson
www.andersknelson.com


As I recall you had to bulk erase the old diskette and then you could 
format it as 720 - covering the 1.44 hole of course.


Not bulk erasing (the side of a Weller soldering gun works just fine) 
led to erratic results. We all have Weller guns for fixing computers, eh?


John :-#)#




On Tue, Apr 30, 2024 at 1:00 PM Mike Katz via cctalk 
wrote:


Does anybody have any extra 720K (double sided, double density) 3.5"
Floppy Disks that could use a good home?

If so, please email me directly at bit...@12bitsbest.com.

Thank you,

   Mike



--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: typical IC kits on Amazon and elsewhere

[John Robertson via cctalk]

On 2024/03/30 7:53 p.m., Glen Slick via cctalk wrote:

On Sat, Mar 30, 2024 at 5:11 PM Jonathan Chapman via cctalk
 wrote:

Standard TTL 74XXX is drying up rather quickly. Futurlec still has some
TTL but 7404s are all gone. Even LS is hard to find.

Ours comes from Mouser, between two part #s they have over 7,000 74LS04s in DIP 
packaging in stock. Didn't check ACT, HCT, or ALS. I don't think we've had a 
7400 series part that we couldn't just order off Mouser in recent history, and 
we're usually buying QTY 100.


You can also buy parts direct from TI, for example they currently show
around around 3000 SN74LS04N parts in stock.

https://www.ti.com/product/SN74LS04/part-details/SN74LS04N

The prices for that part match the current Mouser prices of $0.674
each, or $0.519 each if you buy at least 4 tubes of 25 parts.

I've bought some tubes of 74LS parts direct from TI in the last year.


Interesting, but does TI offer free international shipping with import 
duties & taxes covered if you order over $100US?


John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: FW: Re: ADM3a screen rot.

[John Robertson via cctalk]

On 2024/01/29 12:45 p.m., William Sudbrink via cctalk wrote:

Sellam Abraham wrote:


I think you were fine.  That's how you discharge them anyway.  You were just 
missing the grounding wire :)

Yes, I have one set up for just that purpose.  Wire clamped to the shaft with 
an alligator at the other end.
But I was so pissed off, I just grabbed a screwdriver off of my workbench.  I'd 
rather not be the electron sink
In this case.  I've never taken a hit off of a CRT have you?

Bill S.


I had a chat with an electrical engineer about discharging old picture 
tubes many years ago, and he highly recommended using a suitable 
resistor array - like a HV probe to drain the charge on B monitors. 
Particularly ones that had a separate HV diode. He told me that 
discharging with a screwdriver can pass too much current (caused by a 
cascade of charges) through the diode array and damage them.


This explained a problem we were having with B XY monitors made by 
Electrohome and Wells Gardner where the diode that was mounted between 
the HV transformer and the picture tube would fail and run hot, over 
heating the silicon rubber caps on the ends. I've not lost any HV diodes 
on machines since using our HV probe to discharge since that time.


John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Looking for 1970s OAK keyboard switches...

[John Robertson via cctalk]

On 2024/01/25 6:28 a.m., Paul Koning wrote:



On Jan 24, 2024, at 3:52 PM, John Robertson via cctalk  
wrote:

I've been hunting for a while now for OAK PCB mount keyboard switches that I 
can't find a part number for. I've attached a product listing for the switch 
that shows it pretty well. DPST-NO preferred.

Only $0.40 in the early '70s!

I don't know about Oak, but I remember that Cherry switches were still 
available (new) fairly recently.  A friend of mine used them to build replica 
PLATO keyboards -- using the same switches that were in the original.

paul

Cherry switches are quite different in size and mount from the ones I'm 
looking for unfortunately.


John :-#(#

[cctalk] Re: Looking for (WTB:) 1970s OAK keyboard switches...

[John Robertson via cctalk]

On 2024/01/24 12:52 p.m., John Robertson via cctalk wrote:
I've been hunting for a while now for OAK PCB mount keyboard switches 
that I can't find a part number for. I've attached a product listing 
for the switch that shows it pretty well. DPST-NO preferred.


Only $0.40 in the early '70s!

Any quantity considered...

Thanks!

John :-#)#

I see attachments aren't permitted, even on of only 70k. When did that 
stop - going back in my archives I see messages from the early 2000s 
that had small attachments. Oh well, I'll make some links:


https://www.flippers.com/images/Misc/OAK_Pushbutton_Switch-1973.jpg

https://www.flippers.com/images/Misc/OAK_MysterySwitchAd.png

Anyone seen any of these? They were used in the first Computer Space 
games...(so on topic - ducking!)


Thanks!

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Looking for 1970s OAK keyboard switches...

[John Robertson via cctalk]

I've been hunting for a while now for OAK PCB mount keyboard switches 
that I can't find a part number for. I've attached a product listing for 
the switch that shows it pretty well. DPST-NO preferred.


Only $0.40 in the early '70s!

Any quantity considered...

Thanks!

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: FYI: Hobbes OS/2 Archive logs off permanently in April

[John Robertson via cctalk]

On 2024/01/10 10:56 a.m., Dennis Boone via cctalk wrote:

  > According to a warning on the site: "After many years of service,
  > hobbes.nmsu.edu will be decommissioned and will no longer be
  > available. You the user are responsible for downloading any of the
  > files found in this archive if you want them. These files will no
  > longer be available for access or download as of the decommission
  > date."

Jason Scott has indicated he has archiving under control.

De


I would also suggest you get archive.org in on it...

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: PDP 11/34 or 11/04 front panel question

[John Robertson via cctalk]

On 2023/12/19 4:26 a.m., Tom Hunter via cctalk wrote:

I just realised that I never followed up on this.

After some research and a few phone calls to manufacturer support lines I
settled on SikaBond SprayFix as the glue.

...

The front panel has now been re-assembled and is fully functional and
beautiful.   :-)


Might you have Before and After photos?

Sounds like this is a useful product to have in the shop!

Thanks,

John :-#)#



On Tue, Nov 7, 2023 at 9:33 AM Tom Hunter  wrote:


The PDP 11/34 and 11/04 front panels (both operator and programmer) use a
somewhat stiff plastic sheet of 1.0 mm thickness with DEC logo, model
designation, labels for the keys printed on it, cut-outs for the keypad and
knob and red transparent sections for LEDs and 6 digit 7-segment display.

I don't know what the industry calls this type of plastic sheet? Is it a
"decal"???

This plastic sheet is (was) fixed to an anodized aluminium plate (1.6 mm
thickness) using some type of glue which has deteriorated so that the
plastic sheet has separated from the aluminium plate.

The glue looks like it has been sprayed on and has a light yellowish-brown
appearance. The glue readily dissolves in ethyl-alcohol and acetone, but is
unaffected by water, petrol (gasoline) and dry cleaning fluid (white
spirits).

I would like to glue the plastic sheet back onto the aluminium plate, but
worry about damaging the plastic sheet and/or paint by the solvents in
typical glues.
Also some glues don't allow any adjustment once you combine the two halves
of whatever you glue together.

What type of plastic is this plastic sheet likely made of (polycarbonate?)
and what paint was used? I am asking to determine what solvent based glues
may attack either the plastic sheet or the painted surfaces.

The dark grey and transparent red paints are applied to the back side of
the plastic sheet, so they are vulnerable to solvent attack when glueing. I
tried ethyl-alcohol in one corner which is obscured by the cast metal
surround and some of the dark gray colour came off with the alcohol and
gentle rubbing.

Has anyone successfully glued back the plastic sheet to the aluminium
plate? If yes, what type of glue did you use and how exactly did you do the
operation?

Any suggestions, advice or tips?

Thanks and best regards
Tom Hunter




--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Free to good home HP 7510a Photo Plotter - UK

[John Robertson via cctalk]

Location?

On 2023/11/16 2:24 a.m., Dave Wade G4UGM via cctalk wrote:

Folks,

  


Trying to reduce the weight in my loft and I would like to donate my HP
Photoplotter to a good home.

. Photos of the plotter and some sample plots are on my OneDrive here:-

  


https://1drv.ms/f/s!Ag4BJfE5B3ongspXY7zySSZsDj-WMg

  


It has both serial and IEEE interfaces and uses HPGL like the GP and Roland
pen plotters.

The plots on there are the samples built into the plotter taken on a Fuji
XE-1 digital camera and are cropped because the Fuji does not have a full
frame sensor.

The tube is actually a white tube and the colours are generated by rotating
colour filters.

Its powered by a 68000 and you can see the various boards in the pictures.

  


Dave

  

  



--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: ROM data for Lear Siegler ADM31?

[John Robertson via cctalk]

Hi Peter,

Thanks, I'll check with Ian if he tried those or not...

John :-#)#

On 2023/08/03 11:58 a.m., Peter Ekstrom wrote:

Hi John,

Would these be what you are looking for?

https://bitsavers.org/pdf/learSiegler/ADM_31/firmware/

-Peter

On Thu, Aug 3, 2023 at 2:47 PM John Robertson via cctalk 
 wrote:


I sold my Lear Siegler ADM31 recently and the new owner (Ian) has
found
that one of the ROMs failed before he could archive it - or it was
defective to start with.

So my question to the list is - does anyone have the ROM codes (there
are three of them) archived?

I don't think Ian is a member of this list, otherwise I'm sure I
would
have spotted a post with a subject line like mine...

Thanks!

John :-#)#

-- 
                  John's Jukes Ltd.

7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
flippers.com <http://flippers.com>
  "Old pinballers never die, they just flip out"



--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] ROM data for Lear Siegler ADM31?

[John Robertson via cctalk]

I sold my Lear Siegler ADM31 recently and the new owner (Ian) has found 
that one of the ROMs failed before he could archive it - or it was 
defective to start with.


So my question to the list is - does anyone have the ROM codes (there 
are three of them) archived?


I don't think Ian is a member of this list, otherwise I'm sure I would 
have spotted a post with a subject line like mine...


Thanks!

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Don Lancaster has passed away at 83

[John Robertson via cctalk]

On 2023/07/01 1:10 p.m., Sellam Abraham via cctalk wrote:

Don Lancaster passed away on June 7.

https://gilaherald.com/obituary-for-don-lancaster/

I hope his website is well preserved:

https://tinaja.com/

Sellam


web.archive.org has many copies archived:

https://web.archive.org/web/202300*/https://tinaja.com/

A sad day none the less.

John

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Recovering floppies attacked by mould

[John Robertson via cctalk]

On 2023/05/25 5:11 p.m., Sellam Abraham via cctalk wrote:

Tom,

You may save yourself some time with this nifty contraption ==>
https://www.ebay.com/itm/303620862566

It's a floppy disk cleaning apparatus.  You place the floppy disk into the
frame, apply your cleaning solution and cloth to the index opening, and
then manually spin the disk.

Sellam


If you have a 3D printer then Thingiverse has 3.5 and 5.25 inch floppy 
cleaner files:


https://www.thingiverse.com/search?q=floppy+disc+cleaner=1=things=relevant

John :-#)#



On Thu, May 25, 2023 at 3:36 PM Tom Stepleton via cctalk <
cctalk@classiccmp.org> wrote:


Greetings,

Amidst all the floppy archiving discussion, here's a slightly different
question:

The weather is warmer now where I live, so it's starting to be a good time
to do messy work outdoors. I have some mouldy floppy diskettes that I'd
like to try to read (mostly 5.25"), plus a good flux reader. What is the
best way to attempt to image these floppies?

My thinking right now is that for each floppy I can attempt this procedure:
- remove the mouldy cookie from the infected disk jacket; discard the
latter
- give the cookie the best clean I can (how?) and allow to dry
- place the cookie in a clean disk jacket
- attempt to image
- clean floppy drive heads

Does this seem like a sensible plan? If so, what would be the best way to
clean as much mould off the cookie as I can? Tools that come to mind are
distilled water (tap water here is full of chalk), dish soap,
cyclomethicone, and of course more fearsome solvents. I have kimwipes,
microfibre cloths, and... 200-grit sandpaper, I guess :-)

Thanks for any advice,
--Tom



--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Schematics for Lear Siegler ADM31?

[John Robertson via cctalk]

On 2023/04/23 3:16 p.m., Glen Slick via cctalk wrote:

On Sun, Apr 23, 2023 at 3:10 PM John Robertson via cctalk
 wrote:

Oh, I am missing two key caps for the ADM31, anyone have spares? Not
sure what is printed on them at this point, but any caps would be better
than missing ones to start!

Keyboard photo to see what key caps are missing:

https://terminals-wiki.org/wiki/index.php/Lear_Siegler_ADM-31
https://terminals-wiki.org/wiki/images/2/29/Lear_Siegler_ADM-31_321477505131-3.jpg


As I remember (machine is at shop, and I'm not) I am missing the top row 
far left - DEL/CHAR/INS - and the top row right of that section - SKIP.


I need to confirm on Tuesday, but that link is a major help!

Thanks,

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Schematics for Lear Siegler ADM31?

[John Robertson via cctalk]

On 2023/04/18 8:48 p.m., Tony Duell via cctalk wrote:

On Wed, Apr 19, 2023 at 2:37 AM Tom Hunter via cctalk
 wrote:

... or four $20 power transistors to protect a 10 cent fuse like on the DEC
VR-14 display.

In general the transistor(s) will fail short-circuit, thus taking out
the fuse too.

Some switch-mode power supplies use special fast-acting fuses which
can actually be more expensive than the chopper transistor.

-tony


In the end replacing the capacitors got the supply running. And I 
checked the resistor that looked overheat, and it was 34R which is 
within 15% of the value shown on another 1001 supply that is close to 
the one (same part numbers and values for a number of the parts) in my 
ADM31.


The supply puts out +5VDC, +17VDC (unreg), -17VDC (unreg), and 70VDC 
(unreg).


The board appears to work - I have 5VDC on the MB, and I get a BEEP, and 
there is some sort of data happening on the DB and I am getting data on 
the Vertical, Horizontal, and Video signals to the monitor. Monitor 
isn't lighting up - no HV (I've recapped it too), so I have to put on my 
monitor hat next.


Stay tuned if interested...

Oh, I am missing two key caps for the ADM31, anyone have spares? Not 
sure what is printed on them at this point, but any caps would be better 
than missing ones to start!


Thanks,

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: flipchip cleaning and pin corrosion inhibition

[John Robertson via cctalk]

On 2023/04/23 10:00 a.m., Paul Koning via cctalk wrote:



On Apr 23, 2023, at 12:54 PM, Fritz Mueller via cctalk  
wrote:

Hi folks,

I’ve been picking my way through a PDP-8/L restoration lately.  I’ve found that 
everything in the machine is covered with a uniform layer of dark “soot” 
(enough to blacken your hands while working with it) which I would like to 
clean up.  Perhaps the “soot” is actually from a decomposed air filter, as I 
don’t imagine this machine was operated in a smoky environment, and there is no 
smoke odor.

I usually use 99 IPA and cleanroom wipes for spot cleaning these sorts of 
things, but in this case there is so much of it that I feel that would just 
push the soot around rather than clean it off.  I think some sort of actual 
rinse would be needed here.

I’ve been eying the dishwasher, for the subset of flip chips that that are just 
DIP logic, carbon comp resistors, and ceramic bypass caps, anyway.   But I 
haven’t been brave enough to try that yet...  Most of the logic here has date 
codes to ’68 or ’69, so I’m inclined to treat it gently.  Any suggestions for 
approaches to clean this up?

Dish washer soap may be caustic.  Detergent for washing dishes by hand may be a 
better choice.


Follow-on question: the majority of the legs on these old DIPs are showing what 
I’d call “moderate” corrosion — nothing looks like it is in danger of being 
eaten all the way through, but the process is underway.  I was wondering if 
something like a light shellac or other inhibitor could be brushed over these 
pins to at least slow their inevitable demise?

I wonder if you might be seeing corrosion caused by leftover flux.  Modern flux can be of the "water 
soluble" kind, which indeed washes away nicely with warm water; I've used that for surface mount 
projects.  The traditional flux is rosin flux.  That can be removed with a solvent but that wasn't 
necessarily done.  Amateur project built with that typically would not be cleaned, and that was generally 
considered ok.  A bit like modern "no clean" flux.  But flux is somewhat corrosive, and "no 
clean" may mean simply that it's not an issue within the life expectancy of the device.  So -- you might 
see if rosin flux remover does anything.

paul

I use Dow Corning #4 Dialectic Grease to reduce or prevent corrosion on 
power and signal connectors. Read the spec sheets on that stuff, it is 
really good for metal on metal connections. I imagine it would work well 
on those silver alloy IC legs that are gradually oxidizing away...


John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Schematics for Lear Siegler ADM31?

[John Robertson via cctalk]

On 2023/04/18 9:40 a.m., Tony Duell wrote:

On Tue, Apr 18, 2023 at 2:51 PM Tom Hunter via cctalk
 wrote:

The blown out resistor likely has "blown out" for a reason.
The replacement will probably suffer the same faith unless you find the
root cause.


As soon as I saw 'Boschert' mental alarm bells triggered

Boschert made a particularly unfriendly (to the repairer) type of
SMPSU which I call the '2 stage'. I can explain how it works if
necessary, but be warned that with one of those if a particular power
transistor fails (and it often does), it takes out a couple of other
power transistors, the current sense resistor, numerous small
transistors, the regulator chip, the fuse and sometime PCB tracks.

They're not all like that, but I will agree that a burnt-out resistor
in an SMPSU nearly always means other components have failed.

It's likely the same PSU was used in other devices, you might want to
look through all the service manuals you can find to see if it turns
up. Can you make a photo of the PSU available somewhere in case
somebody recognises it.

-tony


I like to start with schematics before poking too much...

Photo of the SMPSU:

https://www.flippers.com/images/ADM31_Terminal/Boschert_1001_ADM31_PowerSupply.jpg

Burnt Resistor:

https://www.flippers.com/images/ADM31_Terminal/Boschert_1001_ADM31_PowerSupply-burnt_resistor.jpg

Schematics preferred, under the power supply is one I found on bitsavers 
for a slightly later model terminal. If needed I will draw them up 
myself, I just don't want to spend a couple of hours sketching it out if 
I can find a proper drawing.


I assume bad caps (will replace with low-ESR high temp), and possibly 
blown transistor(s)...


*And Gregory Beat sent me a link that covers the 1001 SMPS very neatly:*

http://www.bitsavers.org/pdf/boschert/Boschert_OL25_Single-Stage_Power_Supply_Maintenance_Manual_May79.pdf

and it was buried on bitsavers - where I went before bothering the list!

Thanks folks!

John :-#)#






On Tue, Apr 18, 2023 at 12:20 AM John Robertson via cctalk <
cctalk@classiccmp.org> wrote:


I've checked bitsavers.org (Al does a great job!), and a number of
forums, but no luck finding schematics for my ADM31 that I am trying to
resurrect. The power supply has issues and I need to identify a blown
out resistor - the switching supply is a Boschert model 1001 date code
7943 Revision J.

John :-#)#

--
John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
flippers.com
"Old pinballers never die, they just flip out"




--
  John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
  flippers.com
  "Old pinballers never die, they just flip out"

[cctalk] Schematics for Lear Siegler ADM31?

[John Robertson via cctalk]

I've checked bitsavers.org (Al does a great job!), and a number of 
forums, but no luck finding schematics for my ADM31 that I am trying to 
resurrect. The power supply has issues and I need to identify a blown 
out resistor - the switching supply is a Boschert model 1001 date code 
7943 Revision J.


John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: HP9825A for sale

[John Robertson via cctalk]

On 2023/04/17 9:12 a.m., Sellam Abraham via cctalk wrote:

My initial reaction is that $2,000 seems a "bit" optimistic.

That being said, I'm surprised to see (on eBay's Terapeak) a couple of
these sold within the past year for around $1,100.

Sellam


One sold on eBay for $2492USD...Apr 6, 2023:

https://www.ebay.com/itm/225512121074?hash=item348191e2f2

John :-#)#



On Mon, Apr 17, 2023, 8:52 AM Steve Lewis via cctalk 
wrote:


There is a gentlemen in New Jersey willing to sell his HP9825A

I believe he is the original owner.  It has 4 ROM cartridges (that go in
the front) and several data cartridges for the slot on the top left.

He is asking $2000 but can probably negotiate (as he didn't find any takers
in VCF East).  As far as he knows, everything still works (LED lights came
on when he powered it up a few months ago).

I've met this seller and can vouch for him, but I don't know much about
this particular item.

I have some photos of it at the bottom of this page:
https://voidstar.blog/vcf-east-2023-part-3/

I may try a VCF forum topic about it.  Just trying to help him find a good
home for the equipment.  E-mail/reply direct and I can provide some contact
info.

(BTW not sure if my cctalk posts are working anymore??)

-Steve / voidstar



--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Looking for EPROMs

[John Robertson via cctalk]

On 2023/03/27 2:10 p.m., Mark Linimon via cctalk wrote:

On 03/27/2023 5:38 PM GMT rescue via cctalk  wrote:
have a number of 2764, 27256, have some 27128 I think too

Myself as well, probably down to 1702s.  Right now with some current money
trouble they are looking like assets :-/

mcl


I'm looking for 100 lot quantities of 2716s...something a bit better 
than the Chinese remarks (and very thin legs) would be nice!


Thanks!

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] NOS Tapes 3 X 3M DC 600A 60MB Cartridges (1991)...(speaking of tapes)

[John Robertson via cctalk]

Anyone interested in 3 tapes - has Olympics logo - still in original 
wrapping? Ether pick up at my shop or pay for postage and handling...


John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Identifying a Failed Diode in a Rainbow H7842 Power Supply

[John Robertson via cctalk]

On 2022/11/27 1:21 a.m., Rob Jarratt via cctalk wrote:

I have done a little more probing around. I have found that the 7812 regulator 
that drives Vstart on sheet 1 of Tony Duell’s schematic is shorted, so I will 
have to replace this too. I have not found anything else that looks obviously 
suspicious. I can’t test the output rectifiers for shorts without desoldering 
them, which I would rather avoid. I guess the next step is to replace the 
broken parts and use the light bulb current-limiter method to power on the PSU.

Regards
Rob


My experience with blown 7812s is that there was a surge on the 
unregulated side that went over the maximum input rating for the device. 
You may want to add a Transient Suppression Diode on the input if this 
is a future possibility or a suitable line protection MOV on the input 
just after the line fuse.


John :-#)#

  


From: Rob Jarratt 
Sent: 24 November 2022 21:45
To: 'Mattis Lind' ; r...@jarratt.me.uk; 'General Discussion: 
On-Topic and Off-Topic Posts' 
Subject: RE: [cctalk] Identifying a Failed Diode in a Rainbow H7842 Power Supply

  


Thanks for the suggestion Mattis. The UF4007 has a PIV of 1000V, I had a 
suggestion that the PIV should be 200V. Not sure what rating I should be going 
for here?

  


Regards

  


Rob

  


From: Mattis Lind mailto:mattisl...@gmail.com> >
Sent: 22 November 2022 07:54
To: r...@jarratt.me.uk  ; General Discussion: On-Topic and 
Off-Topic Posts mailto:cctalk@classiccmp.org> >
Subject: Re: [cctalk] Identifying a Failed Diode in a Rainbow H7842 Power Supply

  

  


Hello Rob!

  



Given that before the transistor blew up there had clearly been another
failure somewhere else, I tried to find the original failure. There were no
obviously damaged parts, so I just probed around near the transistor for any
parts that were open circuit or short circuit. I found a diode connected to
the base of the transistor that appeared to be short circuit. So, I decided
to lift one end to check it. As I de-soldered one of the leads, the diode
broke in two. So clearly the diode was either damaged by the failure of the
transistor, or it was the cause of the failure. This is the diode:
https://rjarratt.files.wordpress.com/2022/11/img_20221120_165913.jpg.

  

  


DEC used a lot of A114x diodes in their PSUs. They looked exactly like that 
one. Those are fast recovery diodes. 
https://pdf2.alldatasheet.com/datasheet-pdf/view/7563180/2074/A114F.html

  


I would replace it with a UF4007 or something similar. 
https://www.mouser.se/datasheet/2/849/uf4001-2578577.pdf

  

  

  



I can't quite make out the markings on the diode to know what to replace it
with. I think it says "D610". Would that be the right designation? If so,
can anyone suggest a suitable replacement please?



The diode seems to connect an inductor to the base of the switching
transistor and the collector of the transistor is connected to a
transformer. Should I be looking for other failed parts? Not sure if the
diode failed first and then caused the transistor to fail? Or if something
else has failed which caused these parts to fail?

  

  


Also check all other semiconductors. Also on the outputs. If there is a 1 ohm 
fusible resistor in the base drive circuit check that one as well. In the VT100 
PSUs it happens that it blows.

  

  





I do know that there are no shorts in the Rainbow itself, because I have a
spare PSU that still works fine in the same machine.



I blogged this here (it repeats most of that I have said above):
https://robs-old-computers.com/2022/11/20/dec-rainbow-h7842-power-supply-fai 

lure/

  


/Mattis


Thanks



Rob



--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: Shipping help in Brunswick, GA

[John Robertson via cctalk]

On 2022/11/06 8:37 p.m., John H. Reinhardt via cctalk wrote:
So, I screwed up and in my excitement to find a DEC BA123 chassis (and 
MVII parts) I bid on an Ebay auction where there is no shipping and 
it's "Local Pickup Only".  The problem is that I'm near Fort Worth TX 
and the MVII/BA123 is in Brunswick, GA and I don't really have the 
time to make the 2000+ mile round trip drive to pick it up.


Does anyone here know of a reliable shipping service in Brunswick, 
GA?  Or suggestions for outfits to check out?  Google hasn't shown me 
much other that UPS and FedEx stores.


Failing that, is there anyone near enough willing to pick it up in 
Brunswick that might want it for themselves?


Ebay listing  https://www.ebay.com/itm/334615827742?

If they can put it on a pallet then you can find a Freight Forwarder in 
the area that can arrange a pickup...


Or contact North American Van Lines (NAVL-Beltman) Michele Bianchi 
(630-344-3093) there arranges pickups of equipment (like arcade games 
for home owners) in similar situations. This service isn't as cheap as 
trucking would be from a Freight Forwarder.


Good luck!

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: 7485 chip history??? (Solid State Music SB-1)

[John Robertson via cctalk]

On 2022/09/19 9:51 p.m., ben via cctalk wrote:

On 2022-09-19 10:18 p.m., Tom Hunter via cctalk wrote:

There are a few US based Ebay sellers of the 74L85.

Tom

But most ebay sellers, from the USA seem to sell a item for $6.00 and
$75 shipping to Canada. China $2 and $3 shipping. With Covid all 
shipping is several weeks.

Ben.

How many do you need? I have one or more of 74LS85, 74C85, 74HC85, and 
7485...


Email me directly with which version you prefer. These are all NOS 
parts, not pulls.


John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

[cctalk] Re: 7485 chip history??? (Solid State Music SB-1)

[John Robertson via cctalk]

Ben, I buy lots of stuff from eBay US sellers and most are willing to check/fix 
shipping costs. 
If not then I use a drop-box service where the item is shipped to Oregon, and 
then reshipped to me for a not too horrible cost. 

Lastly, I’ll be back at my shop in Burnaby in a couple of days and can check my 
inventory of TTL chips - might well have your 74L85, and postage is pretty 
cheap within Canada. I’ll try not to hose you too badly on the chip cost!

John :-#)#

> On Sep 20, 2022, at 5:52 AM, ben via cctalk  wrote:
> 
> On 2022-09-19 10:18 p.m., Tom Hunter via cctalk wrote:
>> There are a few US based Ebay sellers of the 74L85.
>> Tom
> But most ebay sellers, from the USA seem to sell a item for $6.00 and
> $75 shipping to Canada. China $2 and $3 shipping. With Covid all shipping is 
> several weeks.
> Ben.
> 
> 
> 

Re: Retire cctech

[John Robertson via cctalk]

On 2022/07/13 3:00 p.m., Dennis Boone via cctalk wrote:

Folks,

I've belatedly realized that it's going to be a bit of a headache to
implement the old cctalk/cctech crossposting duality under the new
version of mailman.

I seem to recall a discussion about retiring the cctech list and just
continuing with cctalk, and that the consensus was in favor of that.

I'll call this message a consent agenda indicating that I plan to do
that, unless there's loud outcry.

De


Are the old posts all archived and searchable? I have a gap from 2016 
through 2022, and before that it is complete back to Mar 29, 2007 (I 
think it is complete).


Merging makes sense to me.

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

Re: OT: mail provider recommendation

[John Robertson via cctalk]

There ain’t no such thing as a free lunch!

What did you think would happen with large free email hosts? They round up all 
the clients and then do what they like with them. 

Google mines emails for data.

I use a private (paid) service via my web site host. I’ve been using it since 
around 1996.

They haven’t changed much over the decades and they do NOT mine my emails!


> On Jun 10, 2022, at 10:01 PM, Carlos Murillo via cctalk 
>  wrote:
> 
> My apologies for asking such an OT question, but I think you guys are the
> most likely to make really useful suggestions.
> 
> Gmail has ceased to provide classic authorization for  smtp, pop3 or IMAP
> access; they want users to employ their new authorization mechanisms.  So,
> which email service do you guys recommend? I'd like to be able to access it
> in the old classic way, from different clients. Ideally it would be a free
> service (I don't store my messages on the server, but rather, download them
> to my client, so I don't need a lot of storage), and also likely to remain
> in operation for many years to come.
> 
> Thanks in advance,
> 
> Carlos Murillo.

Re: Replacement for a DEC 7474 Chip

[John Robertson via cctalk]

On 2022/05/14 10:11 a.m., Rob Jarratt via cctalk wrote:

Hello,

I have found a bad DEC 7474 chip on my M7133 board. Clearly it is a
7474 D flip flop. The problem is I don't know which modern series
would be the best one to replace it with. I am sure I have seen a list
somewhere of modern equivalents for some DEC chip numbers, but I can't
remember where.

If it helps at all, on the PDP 11/24 printset it is E78 on page K6 of the
schematic (p157 of the PDF).

Picture of the failed chip here:
https://rjarratt.files.wordpress.com/2022/05/damaged-dec-7474-4_li.jpg

Can anyone tell me what the best modern equivalent is likely to be?

Thanks

Rob

You are stuck with using an original 7474 family assuming this is 
driving other early TTL. 74LS74, and others simply don't have the drive 
capability to work. You can use 74S74 or 74F74 as they have the same 
output current, the "S" is Schottky, and the other is "F"aster.


I find that https:///unicornelectronics.com is a reliable source of TTL.

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

Re: Different font for second 1 on commodore 1571 drives (and others)

[John Robertson via cctalk]

On 2022/05/05 10:26 a.m., Toby Thain via cctalk wrote:

On 2022-05-05 1:03 p.m., John Herron via cctalk wrote:
Someone at work pointed this out and I've never really thought about 
it. Is
anyone here aware of the decision or reason to use a different 1 
character

for the last 1 vs the first 1?


Got a picture?


They may have run out of that original font if they were setting the 
type with something like Lettraset in the day.


I restore and sell the first coin operated video game - Nutting's 
Computer Space - and they mixed all sorts of fonts on the control panel. 
It was a pain to reproduce it!


John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

Re: cleaning up edge connectors

[John Robertson via cctalk]

On 2022/04/30 4:28 p.m., dwight via cctalk wrote:

Yep. I didn't know it was now made by someone else. Also look at McMaster-Carr. 
You might get a better price.
Dwight


I've used Dow Corning #4 electrical grease for a couple of decades. It 
really helps preventing corrosion and reduces heating of contacts. You 
can also get it from Aklands Grainger.


John :-#)#




From: Ali 
Sent: Saturday, April 30, 2022 3:23 PM
To: 'dwight' ; 'General Discussion: On-Topic and Off-Topic 
Posts' 
Subject: RE: cleaning up edge connectors


Once the corrosion is removed I recommend using DC-4 on the
connections. It will protect the surfaces and keep great electrical
connections. It is a silicon grease that is non-conductive but keeps
the surface clean and improves metal to metal electrical contact. It
doesn't allow oxides to build at the contact surfaces.
It has measurable improvements of even gold on gold. I've used it on
solder to solder as well other dissimilar metals with good results.
I've used it on high current connections to reduce resistive heating up
to 1000 amperes.


Dwight,

Is this what you are talking about:

https://www.aircraftspruce.com/catalog/cspages/dc4.php

-Ali

Re: Looking for old OAK keyboard/control switch...

[John Robertson via cctalk]

Link to image of switch:

https://www.flippers.com/images/Misc/OAK_Pushbutton_Switch-1973.jpg

Thanks,

John :-#)#

On 2022/04/29 2:14 p.m., John Robertson via cctalk wrote:
I've been hunting for a few years for these switches and was thinking 
that perhaps folks here may have seen them or even have some they wish 
to part with...I've hit all the surplus sites, and poured over old 
copies of old Radio Master Parts Catalogue/Encyclopedias - have 7 of 
those, from 1971 going back to 1942 (have visited bitsavers too of 
course)...


This has a total length of 1-5/8", the actuator bar is 5/8 x 3/16 x 
~1/32", the body is 1/2 x 1/2 x 7/8". This uses spring steel snap-on 
clips to secure it in the rectangular hole in the control/keyboard panel.


They have four pins, two are NC and two are NO, no interconnection 
between the pins.


See attached 15kb photo. Hope this doesn't break the system!

Looking for as many as anyone can spare! These are for restoration 
work, so the more the merrier.


Thanks!

John :-#)#



--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"

Looking for old OAK keyboard/control switch...

[John Robertson via cctalk]

I've been hunting for a few years for these switches and was thinking 
that perhaps folks here may have seen them or even have some they wish 
to part with...I've hit all the surplus sites, and poured over old 
copies of old Radio Master Parts Catalogue/Encyclopedias - have 7 of 
those, from 1971 going back to 1942 (have visited bitsavers too of 
course)...


This has a total length of 1-5/8", the actuator bar is 5/8 x 3/16 x 
~1/32", the body is 1/2 x 1/2 x 7/8". This uses spring steel snap-on 
clips to secure it in the rectangular hole in the control/keyboard panel.


They have four pins, two are NC and two are NO, no interconnection 
between the pins.


See attached 15kb photo. Hope this doesn't break the system!

Looking for as many as anyone can spare! These are for restoration work, 
so the more the merrier.


Thanks!

John :-#)#

--
 John's Jukes Ltd.
7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
Call (604)872-5757 (Pinballs, Jukes, Video Games)
 flippers.com
 "Old pinballers never die, they just flip out"