Help Troubleshooting Atari board REVB C010433

[Trellot]

Hi all,

 

ISSUE: I have an old Atari 2600 REVB board, for the six-switch console, which outputs nothing, when powered on, to my mid-1990s Panasoncic Omnivision TV/VHS unit. If I move the main board + switch-board around, while powered on, every so often the screen turns from the channel 2 or 3 solid blue look to a black screen with some buzzing noise from the speakers.

 

Below are the debug steps I have taken thus far:

• Thoroughly cleaned the main board really well to begin. (there was some corrosion near the base of the 12-wire harness connections)
• Pulled all socketed IC chips from the non-working board and tested them in a known good working unit and found that they all work fine (8021E, R6507, R6532).
• Electrically tested the UA78M05 voltage regulator on the switch board with power plugged in and the power switch turned On: (IN = 7.8volts; OUT = just over 5 volts). NOTE: This switch board works on my known good Atari board but with bad washed out colors; only Black and White seems clear on certain games.
• Electrically tested the power adapter on the main board with power On: (both power points read around 8.10 volts).
• Desoldered the 12-pin wire harness from the board and cleaned up the through-hole area really wetll, then ran continuity on all 12 wires which was good.
• Soldered the harness back on and checked continuity again which was good.
• Re-flowed solder on the on-board power adapter as well; got the same voltage readings of around 8.10 volts.
• Ran continuity checks on a lot of the traces on the back of the board and everything I checked seemed good. (NOTE: I'm a Noob so this mean nothing )
• Observation: when power is applied to the board I can feel the chips getting slightly warm so they appear to be getting power.
• I'm using the same 9volt AC Adapter on the non-working Atari as on the working Atari.

 

At this point I'm not sure what to check. I've thought about replacing the voltage regulator and the 2200 UF-16V big cap on the switch board but this switch board basically works on my known good Atari board which makes me think the issue is with the main board. Any suggestions from the AtariAge community would be greatly appreciated.

 

Thanks in advance,

 

Trellot

Edited March 12, 2018 by Trellot

[Trellot]

Did I post this in the wrong Forum perhaps? Curious why it's had no reads or comments yet.

 

Let me know if this should go somewhere else?

 

Thanks,

 

Trellot

[dphirschler]

It's unlikely the mainboard is bad. Maybe dirty sockets?

[Trellot]

It's unlikely the mainboard is bad. Maybe dirty sockets?

Thanks for the suggestion. I've thought the same myself. Might not hurt to replace those sockets, one by one, just to see.

 

~ Trellot