> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Rob Jarratt
> via cctalk
> Sent: 28 June 2017 19:12
> To: 'shad' <shado...@gmail.com>; 'General Discussion: On-Topic and Off-
> Topic Posts' <cctalk@classiccmp.org>
Hello,
now you could try to check the voltages again, just to be sure the fault is
not on the 245.
Following the traces is of course obviously difficult, but if the board is
really only two-sided (no internal signal layers), components are not too
high, and you have a flatbed scanner, you could
> -Original Message-
> From: cctech [mailto:cctech-boun...@classiccmp.org] On Behalf Of shad
> via cctech
> Sent: 26 June 2017 21:57
> To: cct...@classiccmp.org
> Subject: RE: DECstation 220 - Out of Ideas?
>
> Hello Rob,
> if you are uncomfortable with sold
Hello Rob,
if you are uncomfortable with soldering, I can replace the IC for you.
Just ship me the board, I will desolder it.
bye
Andrea
On 25/06/2017 11:46, Rob Jarratt via cctalk wrote:
I have done a bit more tracing of components and have come across a
possibly anomaly. The signal that won't go low enough goes to the
input (pin 2) of a 74LS125 buffer.
OK, for SOIC parts, here's my technique. (I've had to
replace quite a
> -Original Message-
> From: Dave Wade [mailto:dave.g4...@gmail.com]
> Sent: 25 June 2017 20:26
> To: r...@jarratt.me.uk; 'Rob Jarratt' <robert.jarr...@ntlworld.com>; 'General
> Discussion: On-Topic and Off-Topic Posts' <cctalk@classiccmp.org>
> Subject: RE:
Heheh, that's a cool idea. I use a post-it note, sliding a non-sticky side
under the pins (from the rear of said pins) as I drag the iron across all
the pins.
=]
On Sun, Jun 25, 2017 at 11:27 AM Pete Turnbull via cctalk <
cctalk@classiccmp.org> wrote:
> On 25/06/2017 11:46, Rob Jarratt via
e 2017 11:47
> To: 'General Discussion: On-Topic and Off-Topic Posts'
> <cctalk@classiccmp.org>; 'Ian S. King' <isk...@uw.edu>
> Subject: RE: DECstation 220 - Out of Ideas?
>
>
>
> > Thanks Ian. Unfortunately I don't know of any schematics. I suspect
> > you are ri
On 06/25/2017 11:41 AM, Rob Jarratt wrote:
> Thanks Chuck, I had seen some mention of Chip Quik. You say soldering a new
> part is straightforward, but I am not clear how that works, is the solder
> left behind on the pads so you just heat the pins?
As mentioned, I use the toothbrush to scrub
> When replacing components on an SMD board, I prefer to use a low-temp
> fusible alloy such as "Chip Quik":
>
> http://www.chipquik.com/store/
>
> A nice kit, but really, any low temp fusible alloy will work. I use
> Cerrobend as a
> powder, packed around the IC.
>
>
On 06/25/2017 09:24 AM, Rob Jarratt via cctalk wrote:
> Thanks Pete, so there is enough of a chance that I have found the
> culprit to make it worth the effort of desoldering it.
>
> I have been wondering for a while about getting a hot air rework
> station. There are lots of cheap Chinese ones
> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Pete
> Turnbull via cctalk
> Sent: 25 June 2017 16:12
> To: cctalk@classiccmp.org
> Subject: Re: DECstation 220 - Out of Ideas?
>
> As soon as I saw "74LS125"
On 25/06/2017 11:46, Rob Jarratt via cctalk wrote:
I have done a bit more tracing of components and have come across a
possibly anomaly. The signal that won't go low enough goes to the
input (pin 2) of a 74LS125 buffer.
As soon as I saw "74LS125" I thought, "Oh, yes, another one". That's a
> Thanks Ian. Unfortunately I don't know of any schematics. I suspect you are
> right about it being a wire-OR because the documentation for the P82C206 says
> its output is tri-state. As everything is soldered on rather than socketed
> (except
> the ROMs) I am not sure I can measure any
> -Original Message-
> From: Ian S. King [mailto:isk...@uw.edu]
> Sent: 25 June 2017 01:07
> To: r...@jarratt.me.uk; Rob Jarratt <robert.jarr...@ntlworld.com>; General
> Discussion: On-Topic and Off-Topic Posts <cctalk@classiccmp.org>
> Subject: Re:
On Sat, Jun 24, 2017 at 4:17 PM, Rob Jarratt via cctalk <
cctalk@classiccmp.org> wrote:
> As I mentioned in an earlier email, I have been trying to fix a DECstation
> 220. I have made what I think may be some progress, but I am out of ideas
> now.
>
>
>
> The problem appears to be that the 80286
As I mentioned in an earlier email, I have been trying to fix a DECstation
220. I have made what I think may be some progress, but I am out of ideas
now.
The problem appears to be that the 80286 CPU is shutting down and then the
Olivetti chip is RESETting it repeatedly. The reason for this
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