PET 2001-32N BS, with horizontal lines.

[Muttley Black]

Hello everyone and sorry for the late reply, very busy at work.

I have good news! I start with what Dwight ask me to check. i found no shorted capacitor's. So i replace the 7905 with ST L7905cv at 1.5A cause i saw datasheet on Texas instruments regulator and it was 1.5A.

I plug the beauty, switch it on and....


df.jpg dfdf.jpg

I am very happy!


I need to open and check the keyboard, because the only key that working is the "space" key.
I have some more questions if you will allow me please. But i write them a bit later.

Thank you all!

[daver2]

The simple faults are always the best !

Well done...

Dave

[dave_m]

I need to open and check the keyboard, because the only key that working is the "space" key.

Great work.
There will probably be no need to take the keys all apart. Just get to the bottom of the keys and clean the keypads very well with isopropyl alcohol. Be careful with the many tiny screws holding the key circuit board. Don't leave any screws off when buttoning up the circuit board as a solid mechanical support is needed between the board an the key frame for good operation of the keys.

[Muttley Black]

Great work.
There will probably be no need to take the keys all apart. Just get to the bottom of the keys and clean the keypads very well with isopropyl alcohol. Be careful with the many tiny screws holding the key circuit board. Don't leave any screws off when buttoning up the circuit board as a solid mechanical support is needed between the board an the key frame for good operation of the keys.

Thank you!

I prefer to disassemble all the keyboard for clean the keycaps too. I do your steps with isopropyl alcohol and I post the results here.

One more thing I want to ask is the recap. I am looking forward to recap the electrolytic capacitors with good brand like Nichicon for example. It is a good move yes?

AC360339-9BB7-4FEE-A2F2-B676C6555115.jpeg

Also I want to do the same thing on monitor board.
I want to make on this beauty a nice restoration and give him other 40 years of life.
I don’t know if it is normal but if I place my hand in monitor case the time is working, the screen shaking a bit.

If you have any other restoration tips that you thing that i must do on this computer, i do them with pleasure!

Thank you

[daver2]

It’s not only the electrolytic that are a problem, the little blue or yellow tantalum beads are more problematic.

If you want to give the PET a better chance of survival then you might like to consider these as well.

However, a word of warning, this is no guarantee that the PET will survive intact for a year, let alone 40...

>>> I don’t know if it is normal but if I place my hand in monitor case the time is working, the screen shaking a bit.

Er, don’t put your hand in the monitor case! Or do you mean on the monitor case?

Dave

[Muttley Black]

I understand what you mean about surviving Dave and you are right. I know that it is an old hardware with no guarantee. I just want to replace the components that are more "fragile"? I don’t know if I use the right word.

And yes I meant "on" the case. . When I put my hands in top of the monitor case.

[daver2]

The metal case of the PET and the monitor should be earthed, so putting your hand on the monitor shouldn’t cause interference.

Is your PET earthed properly?

Sorry, I couldn’t resist the “don’t put your hand in the monitor”... thanks for the clarification.

Dave

[Muttley Black]

Ahhh. Of course was not. As the monitor was separated from the body case. As you saw in my photo.

[daver2]

Ahhhh...

Obvious now !

Dave

[Dwight Elvey]

I'm glad to see that replacing the regulator brought it back to life. Still, years of experience has taught me to check all the angles before replacing anything. You should only replace electrolytics that show indications of failing. It is much easier to damage the computer when doing a lot of unnecessary parts replacements. You have a working machine keep it that way.
Dwight