27 Nov
2021
27 Nov
'21
12:40 p.m.
Apologies for the previous email and it?s disgusting formatting, here is a second attempt,
hopefully it?s readable.
Thank you all for your responses and leads,
Responses to some of your questions and some more questions:
"Have you checked/measured whether they're actually faulty?"
Yes I have, in the picture I have provided on the bottom there are the ends of 3
transistor leads. This was one that fell off as I removed the card and by far the worst
corroded, so despite the fact that the rest still work. I need to replace this one.
?I would suspect that these transistors are pre-drivers for the power transistors and may
not be super critical to get an exact replacement."
Would an NPN or PNP with the same HFE suffice, or do I need to know more? Forgive me but I
am a complete idiot when it comes to this kind of circuit design and their tolerances.
"Did you get manuals with the printer? If so it should have ALDs
(schematics)."
Unfortunately not, and nor can I find any online.
"The 3286 printers and 3277 terminals where infamous for intermittent problems"
Excellent, glad I bought something that will provide the true IBM experience.
Thank you,
Al
On 27 Nov 2021, at 20:35, Bill Gunshannon via cctalk
<cctalk at classiccmp.org> wrote:
?On 11/27/21 3:17 PM, Van Snyder via cctalk wrote:
Make sure you keep the room air conditioning in working order if
you want an operating 1401. :-)
bill
On Fri,
2021-11-26 at 22:33 -0800, Brent Hilpert via cctalk wrote:
The Computer
History Museum in Sunnyvale, CA has two IBM 1401's that
are in operating order. One of the problems they had in getting one of
them to work was that some of the IBM transistors also have plated
steel leads that had rusted through. Ask Rob Garner <robgarn at mac.com>,
the leader of the 1401 restoration project, if he recognizes the
numbers. On 2021-Nov-26, at 1:52 PM, Al via cctalk wrote:
A while ago I received an IBM 3286 printer,
annoyingly some of the
transistors in the printer section have been corroded. What I am
having trouble with is reading the part codes and finding a modern
equivalent of them.
There are two types.
One has a Ti logo and two sets of numbers (attached). Does anybody
know which numbers are the part numbers and if they are IBM house
numbered?
Photos of the Ti transistors and card assembly:
https://drive.google.com/drive/folders/1JTnsWS4A8NrYJNFsqK2ejOeqqJNjoF1w?us…
Have you checked/measured whether they're actually faulty? Yes, they
look terrible, but that doesn't mean they're faulty. It looks like
minor corrosion of the steel case under its plating; unless it's all
the way through the die is probably fine and cozy inside. The
electrically active parts of the transistor typically aren't as
susceptible to corrosion as the steel case is.
(Notable exception to this being 70's-era TI ICs with plated steel
pins. I've also seen some Motorola ICs with corroded pins).