Re: Reforming Capacitors: EAI Analog Computer TR-48
- --- In email@example.com, joshbensadon <no_reply@...> wrote:
>1) Date codes on many components are in the format YYWW where YY is the year (72, 73, 74....), YY is the week of the year (01-52).
> I'm still working on the EAI Model TR-48 Analog Computer. I've found stacks of information on Analog Computers, there is much to learn about them. I am guessing this project will take 6 months or more.
> In a few weeks, I'll be testing the power supplies, but I'm concerned about the old capacitor cans. I've done an hour of reading the internet about "Capacitor Reforming".
> Does anyone have any experience or remarks to make about these CAN capacitors from the late 50's or early 60's?
> PS. We still haven't found an exact date for this computer.
2) How about you describe the brand, model and show a photo of the "capacitor cans" you are talking about? It would be very informative. A schematic would help also.
3) Here's a Web site that at my glance, seems to have a lot of information and links:
4) My advice to anyone doing restoration of computers, is to get a Web site, and put your work UP THERE. People will come to you, and you will have a place to put the kinds of docs I just asked about. 20th century Web sites, like mine, are also a means to help organize one's thoughts and activities.
I appreciate your questions and reports. They encourage me to do more about analog computers, myself. The first computer I ever worked on, was an EAI TR-series system; at the university I attended in the Psychology Department, when I was working to pay my tuition. I cleaned it up but never ran it. I have some analog computers now, but they are not priorities to work on, as only Bill Degnan talked much about them in the MARCH group. That's changed.....
>Yes, In my opinion you are correct.
> Here's a transistor with 430 on it. Would that make it 1964, week 30?
> Transistor part number is 2N1218. Or does the 430 refer to the factory the
> transistor was made? or other?
> Photo of transistor posted in the photos/Josh Bensadon folder of this group.
> I've seen some IC's with only a 3 digit code on them (not part of this analog
> computer). Case in point is the following:
> RCA H 650
> Is that to mean 1976 week 50?
> H being the factory where it was made?
In the early years of semiconductors most parts have three digit date codes.
You have to know the approximate decade the part was first produced to get the
Sometimes you have trouble telling the part number apart from the date code.
In the 1970s a lot of the 7400 series ic's had date codes like 7414 and a part
number like 7404.
I was always having trouble with those.
A good history of early transitor marking can be found here.