10 uF/25 V tantulum or electrolytic capacitor. The silver stripe on the tantulum marks its positive lead. For the electrolitic caps the longer lead (also marked on the casing) is negative.

If I'm not mistaken, there are five missing caps on your picture: C125, C126, C127, C128 and C???:

I looked for those... there's like 10 million different kinds... or well maybe 10 thousand!
Does it matter what kind? How expensive? It's wild!
Thanks OIdbie!

Oh, and here's the original pic after I removed the battery and cleaned things up and before removing parts...

The one on the picture is tantulum type capacitor 10 uF/25 V. If you can't find such a type, in your case you may use electrolytic 10 uF/25 V as a replacement. Mind the polarity when solder the new one or the cap will explode.

joebelter@hotmail.co wrote on 2025-01-23, 02:03:

Oh, and here's the original pic after I removed the battery and cleaned things up and before removing parts...

Ok. So only one capacitor (C128) is missing.

Just buy them from anywhere? As long as it says 10uf 25v Tantalum? No other specs?

Thanks SO much!

joebelter@hotmail.co wrote on 2025-01-23, 02:18:

Just buy them from anywhere? As long as it says 10uf 25v Tantalum? No other specs?

Yep. A 10 uF tantulum throgh-hole mount capacitor for maximum voltage of 25 V. That's all.

Once again: Mind the polarity of the leads when soldering the new capacitor or it will explode when soldered in reversed position.

Thanks Oldbie!

They're "only" decoupling capacitors to reduce emi.

It should work without them if it is capable of working.

You'll find most caps are kinda redundant in that boards will work with a few missing. Especially the small ones.

Lose too many though and stability is at risk.

If you're familiar with car audio, they're used like high-pass filters.
Meaning they let high frequency noise though, but block the lower frequency signals from passing.

As you can see, there were more in the original design, but it would seem production testing showed several weren't needed - and it still met emi rules so they were left off from factory.

As I'm fairly new to repairing electronics, I could REALLY use some resources on how to contact people who know how to do this stuff; I live in a small town and don't have resources available to me locally. Youtuber's are great for learning, but you really can't ask specific questions. Where are the best places to post/ask? I'm willing to learn but need folks willing to answer questions like yourself.
Love to hear any and all suggestions!
Thanks again,
Joe

Well, after getting the rest of the corrosion I found that I have to replace the 20 pin socket. It was gone. (I imagine I should keep the IC, right? The pins look ok, just not shiny)
What do I get?
Also should replace the white power supply connector as well since it went under there too.
Please let me know what I need to order.

Thanks so very much!

It's not 20 pin, but 40 pin DIP socket. You can try to clean the corroded pins of the M5L8042-153P keyboard controller chip with some vinegar, then use a fine sandpaper and finally tin them with very thin layer of soldering tin (you have to use some good soldering flux).

So just buy any ol 40 pin DIP socket then?
Thanks again Oldbie!
Joe

I also can't find anywhere that sells the 12 pin power supply connectors.
Maybe they are called something else?
Joe

The socket is not just any 40-pin socket, but "40-pin Dual In-line Package socket" (DIP socket). These also have a size - the most important are the width between the two sides with the contacts and the pin offset. Measure this size from the original corroded socket or from the keyboard controller chip. The pin offset must be 2.54 mm.

About the power connector - try to search for "male AT power connector" or "molex 15-48-0106" (you'll need two pieces with 6 pins).

A replacement to the original AT power connector is two-pieces of Molex 36642-0001, see here: https://www.molex.com/en-us/products/part-detail/366420001
There are also links to various distributors.

Check this out... there aren't any distributors that carry them, and places like Mouser won't ship to USA!
Wierd!

Odd that you can't get them from Mouser. I've ordered them from there before without problem. I live in the US. These are just black instead of white.

Specifically: https://www.mouser.com/ProductDetail/Molex/36 … tmkhjTfQA%3D%3D

Same one is available over on DigiKey as well: https://www.digikey.com/en/products/detail/mo … 6420001/4143772

I just put them in my cart and it's not giving any restricted shipping to my address here in Wisconsin.

I also need to replace that 4 pin header strip along the right side of the board...
I don't know what they are called, or what pitch to get. The same 2.54mm?
Thanks again for answering my DUMB questions!

Joe

You can get those just about anywhere, and they're cheap. I just buy them over on Amazon, but Mouser and all the others have them too.

Like these for example: https://www.amazon.com/MCIGICM-Header-2-45mm- … /dp/B07PKKY8BX/

Just search for "2.54mm header".

They simply snap apart into whatever number you need. A simple pair of pliers is all you need for a clean break, or the edge of a table/desk. You get the idea. 😀