[cctalk] Re: 1974 No Name Terminal

[Brent Hilpert via cctalk]

On 2023-Jul-05, at 9:45 AM,  
 wrote:

> Thank you!  I couldn't remember if I'd posted it here before, I've been off
> the list for a while.
> 
> Because I don't know really anything about it, I'd been operating on the
> belief the power sent from the PSU was DC.  So maybe that's my issue.  There
> is a single 10 pin connector from the PSU to the motherboard.  I tested for
> DC and found the following:
> 
> Brown- +5V
> Red- +5V
> Orange   - +5V
> Yellow   - -16V
> Green - +16V
> Blue  - -0.8V
> Purple - GND
> Grey - GND
> White- GND
> Black- -2.4V
> 
> I'm not sure if the +16 and -16v need to be adjusted, or if they are that
> high because they don't have a load during my testing.  The -16V is directly
> connected to the VEE on a nearby 1488, and I think the max voltage there
> should be -15V.
> 
> The blue and black are the ones that didn't seem right.  But, if they're not
> DC then maybe that's my issue.  Also last night I found more cold solder
> joints, so maybe one or both are affected by that.  I will test with my DMM
> as AC instead of DC and see if I get something there instead.  Barring that,
> I'm working on a schematic of the PSU to try and figure out what it's
> supposed to be delivering.
> 
> Like I said, very tempting to plug in, I suspect it may be just fine.. but..
> there's a lot of chips to blow up here if I'm wrong.

Seeing as how you're looking at the connections from the PS to the logic, 
raises the question of how the monitor is being powered: does it have it's own 
PS from 120VAC, wired to the PS directly, or from the PS via the logic board.

Some points about supplies:
- The memory chips are 1402 256*4 PMOS shift registers. These need 
supplies of Vcc = +5 and Vdd = -5 to -9V.
  The 1402s also need higher voltage clock signals, between Vcc-15 and 
Vcc-17 (may be -10 to -12 relative to gnd).
  The two MMH0026 ICs beside the 1402s are the clock drivers for the 
1402s.
- The 3258 character generator needs -12 (and +5).
- The 1602 UART probably needs -12 (and +5).
- The RS232 needs +something and -something line-drive levels of course.
- There's what looks to be a potted crystal clock module on there, 
might check what its supply is.
  Could be +5, but could be something else.
- There's probably a MOS keyboard encoder that may require some 
supplies besides just +5.
- Some of these supplies may be derived via components (e.g. zener & 
dropping R) on the logic boards.
- And of course the monitor needs its supply(s).

Seeing as how you have some odd things appearing on the PS, if it were me, I 
would be:
- RE-ing the PS thoroughly,
- figuring out the power connections on the logic boards to these 
special ICs,
- figuring out the monitor power supply/sources
.. so it's known how all these requirements are intended to be met before 
powering the whole thing up.

I recently refurbished a Teleray terminal from the same period. It uses MOS 
shift registers from the same family (1404s) and similar funky clock drivers. 
The power supplies design was more straightforward than what you appear to be 
dealing with. On things like this I also like to look at the DB25 connector to 
see exactly how it's wired - fixed-level ctl-sig outputs, connections for 
ctl-sig inputs that may be required, DCE vs DTE, whether there are any 
non-EIA-standard connections present.

[cctalk] Re: DEC VT180 "Robin" Maintenance Prints?

[Robert Armstrong via cctalk]

>Rob Jarratt  wrote:
>Have you checked here: http://9track.net/roms/ ...

  Hey, thank you!  I didn't know about this particular collection, and he does 
have the ROM dumps for the VT180 Z80 board.

  I'd still like to find a schematic, though!

Thanks again,
Bob

[cctalk] Re: 1974 No Name Terminal

[Brad H via cctalk]

Thank you!  I couldn't remember if I'd posted it here before, I've been off
the list for a while.

Because I don't know really anything about it, I'd been operating on the
belief the power sent from the PSU was DC.  So maybe that's my issue.  There
is a single 10 pin connector from the PSU to the motherboard.  I tested for
DC and found the following:

Brown- +5V
Red- +5V
Orange   - +5V
Yellow   - -16V
Green   - +16V
Blue- -0.8V
Purple   - GND
Grey - GND
White- GND
Black- -2.4V

I'm not sure if the +16 and -16v need to be adjusted, or if they are that
high because they don't have a load during my testing.  The -16V is directly
connected to the VEE on a nearby 1488, and I think the max voltage there
should be -15V.

The blue and black are the ones that didn't seem right.  But, if they're not
DC then maybe that's my issue.  Also last night I found more cold solder
joints, so maybe one or both are affected by that.  I will test with my DMM
as AC instead of DC and see if I get something there instead.  Barring that,
I'm working on a schematic of the PSU to try and figure out what it's
supposed to be delivering.

Like I said, very tempting to plug in, I suspect it may be just fine.. but..
there's a lot of chips to blow up here if I'm wrong.

-Original Message-
From: Brent Hilpert via cctalk  
Sent: Wednesday, July 5, 2023 9:11 AM
To: General Discussion: On-Topic and Off-Topic Posts 
Cc: Brent Hilpert 
Subject: [cctalk] Re: 1974 No Name Terminal

On 2023-Jul-05, at 8:25 AM, Brad H via cctalk wrote:

> Seems to be RS-232 compatible, which in my experience is unusual for a
terminal in the early half of the 1970s.  It has little serial number
stickers tucked around but they're all random numbers, nothing really lines
up.  A few of the boards have what appears to be serial numbers in the low
hundreds.
> 
> So tempting to just plug in and see what happens, but I'm concerned about
the voltages on two pins that seem off.

What does 'seem off' mean?

One possibility is they are a floating supply for the CRT heater. Not
unusual in those days was just to have an independent 6.3 or 12.6 VAC
secondary on the PS transformer dedicated to the heater and it often
wouldn't be grounded. You could try checking between the two pins with
multimeter ACV range.

This terminal (this specific unit) was mentioned on the list 2 years ago:


https://classiccmp.org/pipermail/cctalk/2021-February/thread.html#57808

2021-Feb-12
Mystery (unusual) 1973 terminal

Around a dozen messages. In one of those messages I list & ref some of the
more-significant ICs from the board photos.

[cctalk] Re: 1974 No Name Terminal

[Brent Hilpert via cctalk]

On 2023-Jul-05, at 8:25 AM, Brad H via cctalk wrote:

> Seems to be RS-232 compatible, which in my experience is unusual for a 
> terminal in the early half of the 1970s.  It has little serial number 
> stickers tucked around but they're all random numbers, nothing really lines 
> up.  A few of the boards have what appears to be serial numbers in the low 
> hundreds.
> 
> So tempting to just plug in and see what happens, but I'm concerned about the 
> voltages on two pins that seem off.

What does 'seem off' mean?

One possibility is they are a floating supply for the CRT heater. Not unusual 
in those days was just to have an independent 6.3 or 12.6 VAC secondary on the 
PS transformer dedicated to the heater and it often wouldn't be grounded. You 
could try checking between the two pins with multimeter ACV range.

This terminal (this specific unit) was mentioned on the list 2 years ago:

https://classiccmp.org/pipermail/cctalk/2021-February/thread.html#57808

2021-Feb-12
Mystery (unusual) 1973 terminal

Around a dozen messages. In one of those messages I list & ref some of the 
more-significant ICs from the board photos.

[cctalk] DEC VT180 "Robin" Maintenance Prints?

[Robert Armstrong via cctalk]

  Does anybody have the maintenance prints for the DEC VT180?The VT180,
aka "Robin" was DEC's CP/M machine in a VT100 chassis.  The terminal part is
just a standard VT100 and maintenance prints for that are easy to find, but
I need a schematic for the actual Z80 CP/M Robin option card.  Can't seem to
find that anywhere.  Bitsavers and Manx have the technical manual which has
some information (although it wastes way too many pages explaining how a
VT100 works!) but no actual schematics.

 

  On the same topic, has anybody dumped the ROMs for this machine?  Again,
not the VT100 ROMs, but the CP/M boot/POST ROMs that are on the VT180 Z80
card.

 

Thanks,

Bob

[cctalk] Re: 1974 No Name Terminal

[Douglas Taylor via cctalk]

At first glance it reminded me of the Hazeltine 1000, I owned one in the 
early 1980's.  Brutally simple terminals, I remember getting a ROM from 
Jameco which allowed the terminal to display lowercase letters.  Pure 
luxury.

Doug

On 7/4/2023 6:57 PM, Brad H via cctalk wrote:

Hi there - not sure how much overlap there is with vcfed's forum, but
thought I would reach out here in case.  I have a terminal from 1974 (based
on date codes I've found on the motherboard).  I'm unable to determine
manufacturer and that would be handy for diagnostic purposes.  The terminal
casing is made out of foam, and although there are some serial numbers
stamped around, nothing really lines up.  The fans inside have zero dust or
dirt, so I'm thinking this may not have seen much use, or may be a prototype
or pilot for something.  It does have RS232 capability.  Interestingly the
screen is set down below the keyboard so that only half of it is visible.

  


My main issue right now is the PSU - I am trying to determine if I'm safe to
attempt powering up the board (the PSU so far seems to be ok, although some
voltages on a couple of pins are mysterious).

  


Anyway, on the extremely off chance anyone has ever seen one of these or
something like it.. any tips would be appreciated. If I can find a manual
I'll feel a lot safer about turning it on.

  


Some pics here:
https://drive.google.com/drive/folders/1-2uEFbi3OKBYr06y6yHnygDiLMtw2Qkj?usp
=sharing

  


Brad

b...@techtimetraveller.com

  

[cctalk] Re: 1974 No Name Terminal

[Brad H via cctalk]

Seems to be RS-232 compatible, which in my experience is unusual for a terminal 
in the early half of the 1970s.  It has little serial number stickers tucked 
around but they're all random numbers, nothing really lines up.  A few of the 
boards have what appears to be serial numbers in the low hundreds.

So tempting to just plug in and see what happens, but I'm concerned about the 
voltages on two pins that seem off.

-Original Message-
From: Sellam Abraham via cctalk  
Sent: Wednesday, July 5, 2023 6:54 AM
To: General Discussion: On-Topic and Off-Topic Posts 
Cc: Sellam Abraham 
Subject: [cctalk] Re: 1974 No Name Terminal

Brad,

That's a new one on me.

But the split CRT reminds me of a 1970s IBM desk computer (it was a computer 
built into a desk, I forget the model number) and it had a similar display.

I wonder if this isn't some third-party IBM compatible terminal?

Sellam

On Tue, Jul 4, 2023 at 10:27 PM Brad H via cctalk 
wrote:

> Hi there - not sure how much overlap there is with vcfed's forum, but 
> thought I would reach out here in case.  I have a terminal from 1974 
> (based on date codes I've found on the motherboard).  I'm unable to 
> determine manufacturer and that would be handy for diagnostic 
> purposes.  The terminal casing is made out of foam, and although there 
> are some serial numbers stamped around, nothing really lines up.  The 
> fans inside have zero dust or dirt, so I'm thinking this may not have 
> seen much use, or may be a prototype or pilot for something.  It does 
> have RS232 capability.  Interestingly the screen is set down below the 
> keyboard so that only half of it is visible.
>
>
>
> My main issue right now is the PSU - I am trying to determine if I'm 
> safe to attempt powering up the board (the PSU so far seems to be ok, 
> although some voltages on a couple of pins are mysterious).
>
>
>
> Anyway, on the extremely off chance anyone has ever seen one of these 
> or something like it.. any tips would be appreciated. If I can find a 
> manual I'll feel a lot safer about turning it on.
>
>
>
> Some pics here:
>
> https://drive.google.com/drive/folders/1-2uEFbi3OKBYr06y6yHnygDiLMtw2Q
> kj?usp
> =sharing
>  Qkj?usp=sharing>
>
>
>
> Brad
>
> b...@techtimetraveller.com
>
>
>
>

[cctalk] Re: 1974 No Name Terminal

[Sellam Abraham via cctalk]

Brad,

That's a new one on me.

But the split CRT reminds me of a 1970s IBM desk computer (it was a
computer built into a desk, I forget the model number) and it had a similar
display.

I wonder if this isn't some third-party IBM compatible terminal?

Sellam

On Tue, Jul 4, 2023 at 10:27 PM Brad H via cctalk 
wrote:

> Hi there - not sure how much overlap there is with vcfed's forum, but
> thought I would reach out here in case.  I have a terminal from 1974 (based
> on date codes I've found on the motherboard).  I'm unable to determine
> manufacturer and that would be handy for diagnostic purposes.  The terminal
> casing is made out of foam, and although there are some serial numbers
> stamped around, nothing really lines up.  The fans inside have zero dust or
> dirt, so I'm thinking this may not have seen much use, or may be a
> prototype
> or pilot for something.  It does have RS232 capability.  Interestingly the
> screen is set down below the keyboard so that only half of it is visible.
>
>
>
> My main issue right now is the PSU - I am trying to determine if I'm safe
> to
> attempt powering up the board (the PSU so far seems to be ok, although some
> voltages on a couple of pins are mysterious).
>
>
>
> Anyway, on the extremely off chance anyone has ever seen one of these or
> something like it.. any tips would be appreciated. If I can find a manual
> I'll feel a lot safer about turning it on.
>
>
>
> Some pics here:
>
> https://drive.google.com/drive/folders/1-2uEFbi3OKBYr06y6yHnygDiLMtw2Qkj?usp
> =sharing
> 
>
>
>
> Brad
>
> b...@techtimetraveller.com
>
>
>
>