Glitches in a modded 2600jr

[vitoco]

My Harmony Encore has glitches in a A/V modded 2600jr:

 

 

The text is almost unreadable. The PlusCart runs OK in this machine.

 

What could be wrong here? Where could I start looking for a solution?

 

Thanks!

 

[+-^CrossBow^-]

Looks more like an issue with the TIA to me...

 

[vitoco]

On 9/29/2021 at 12:40 AM, -^CrossBow^- said:

Looks more like an issue with the TIA to me...

 

I replaced the TIA with the one from my 2600A. Result: success. But...

 

Then I double checked and went back to the Jr's TIA. Result: Sucess!!! A failure was expected... ?

 

The console was opened (uncased), so I moved the power switch directly, and I found that it was very sensitive. Sometimes I just touched it and the glitch appeared. Touched it again, and I got a black screen. Turned off and on again, succeeded, shaked it, glitched, shaked it again, succeeded, and so on.

 

So, it seems that there is something bad with that switch. The 2600jr console was socketed before I received it, and it probably was recapped. The power and color switches are not identical, so I compared them to motherboard photos from the web: the power switch seems not to be the original one.

 

Which kind of failures could be the result of this "bad" switch? Power loss? Noisy power?

 

Thanks...

 

[vitoco]

1 hour ago, vitoco said:

The power and color switches are not identical, so I compared them to motherboard photos from the web: the power switch seems not to be the original one.

I talked too fast... Looking at some other motherboards in the net, it seems that the power switch is also original. Then I have two original but different switches!!! Also, looking at the back of the board, none of them seem to be resoldered.

 

 

This board is Rev D, where the power switch is similar to the one found in Rev F, and the color-b/w switch is the one found in Rev B.

 

But it seems that this mixture was standard for the short rainbow Rev D consoles: 

 

 

[vitoco]

I desoldered the power switch to find a similar one in the local market, but I measured it with a multitester and checked that it was unstable. I expected to get 0 ohm when turned on, but I got a moving range from 20 up to 190 ohm. As the switch could be opened with a little presure, I disassembled it and cleaned all 4 pieces with isopropyl alchohol and reassembled it. Testing it again, I got a fixed 12 ohm when turned on, so I resoldered it to the console. No more unstable and weak power led light.

 

After that, I checked the Harmony cart and the glitches were still there. I replaced the TIA with the one from my old 2600 and the problem was solved. But as I got at least one success using the original TIA, I tried it again, but I couldn't remove the glitch. So I finally gave up and kept the older TIA in the Jr to make it work.

 

At the end, I put the "failing" TIA on the old 2600 and tried it. The Harmony cart didn't show a glitch there!!! I could run a DPC+ game... 

 

Then, there is something wrong with the timmings in the console. The previous owner cut some traces while socketting it, so he added extra wires to complete them. Could this be the reason why?