I think I killed her.. :_(

[bola_dor]

I did recap my TS268.. first test was OK. Started well.
Then I Just wanted to check some voltages and with a little slip of the mutimetwr I shorted center and right leads of Q1 wich is a regulator (D432C1) .
Now I have this screen at startup

20200530_164846.gif (516.2 KiB) Viewed 9571 times

Chequed voltages and are OK.
U7 is hot at touch.. (U6 and U7 are video ram TMS4416)

Should I try to replace the ram or should I test any other thing first.?

[1024MAK]

If you have two RAM chips that are the same age and type and one is getting very hot, renew it.

If however it is just slightly warmer than the other one, it may be okay.

Mark

[bola_dor]

If you have two RAM chips that are the same age and type and one is getting very hot, renew it.

If however it is just slightly warmer than the other one, it may be okay.

Mark

Thing is machine was working ok . And is hard to believe that a single and short slip of the multimeter lead has made this..
Sad.

[1024MAK]

I don't know much about this machine, but if you shorted pins on a power transistor or regulator and one pin was the unregulated input and the other pin was the regulated output (+5V for TTL computer logic supply), even a briefly, it causes an over-voltage on the regulated supply. Some chips when operated beyond their maximum supply voltage suffer internal damage.

This kind of thing is easy to do and then you learn the lesson the hard way (yes, I've done it).

Mark

[jdfan1000]

U7 is hot at touch.. (U6 and U7 are video ram TMS4416)

A hot 4416 is a sign of a toasted 4416. I did something to my 2068 and ended up with the same result. I desoldered all the 4164, put in new sockets, and replaced them, per this article:
https://www.timexsinclair.com/article/a ... -yourself/

David

[bola_dor]

U7 is hot at touch.. (U6 and U7 are video ram TMS4416)

A hot 4416 is a sign of a toasted 4416. I did something to my 2068 and ended up with the same result. I desoldered all the 4164, put in new sockets, and replaced them, per this article:
https://www.timexsinclair.com/article/a ... -yourself/

David

I'll check your article.. have in mind that TS2068 memory are not 4164..
I've already changed U6 and U7 but with partial results.. I have to check everything again..
Thanks!!

[jdfan1000]

Oh, that was a typo. 4416.

[rcade]

We've all done it at some time or another...

RAM chips go bad if you just look at them wrong, so I would first try replacing them.