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lwk13080

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Any body know how to fix this issue
When i switch on/off sound dip it
Turn back to normal
 
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TulioAdriano

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test menu says good
Test menus normally only check the program roms, not graphic roms.

I can barely see what I think it's the glitch you're reporting... if it's the dots around the bosses then most likely the issue is with the OBJ roms.
You need to do a few tests:
  1. If you move your finger around the connectors on the romboard (slide your fingers on the upside prongs) does it aggravate/resolve the issue?
    if so: You may have a disconnected address/data line from one of the EPROMs.
  2. Did you reseat all EPROMs? These are 30+ years boards, so connections can be iffy. Remove and replace all EPROMs, and if you can, clean the pins/slots in the process. Contact cleaner is ok.
  3. Did you reseat the romboard itself? It could be dust/dirt/oxidation blocking some of the address/data lines connection. Try cleaning all connectors.
  4. Did you inspect the traces in the board? Sometimes they may get corrosion even under the solder mask. If you see any darkening within the traces, you could have had one of them broken by corrosion. You will need to do a continuity test on all data lines going to the VDP.
Your problem doesn't look serious and it's most likely fixable with #2 or #3. If test #1 produces some effect, most likely the issue can be addressed within the romboard, and the motherboard is fine.

Good luck.
 
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