Elfen
Well-known member
I would never call another member's work as shoddy or terrible. In fact this LC board's recap was done better than what I could have in comparing it to those I did. And I praised him for it, he does great work. Sorry Uniserver, it's not you. I'm talking about CompuNerd.
But this LC board still eludes me. At first I thought it was noise from the PSU. Nope. The PSU works fine and without noise on other LC Boards, including LC II, LC III and LC 475. So I decided to try a known perfectly working LC PSU from another LC III to this LC. IT SQUEALS!!!
So it's not the PSU creating noise on the lines.
But CompuNerd admitted long ago that he put one of the ROMs backwards on this board and killed the ROM. An honest mistake, we all done that at one time or another. So it took me a while to get a new set of ROMs, having to buy a complete set of 4 ROMs from ebay for $9. I replaced that 1 dead ROM and got the LC working again but it squeals heavily! Today I decided to replace the other three ROMs, and it still squeals but not as badly. Put back in the old ROMS and it squeals loudly. Replace the ROMs, and its quieted down but still squealing. Interesting...
So part of the problem is solved but it is still there. Like Schödinger's Cat being there and not there at the same time. So I'm thinking, could a replacement cap have blown at the audio section from the ROM being placed backwards? To me they look fine under a magnifying glass. Voltage is OK. The problem is that it continues to squeal.
Furthermore - with the ROMs replaced, it will quiet down after a long while (a 1/2 hour or so) to a white noise static background noise. Audio Amp Chip problem?
To make sure that it is not remaining cap goo on the board causing this, I have washed this board again and again.
Other than this "little problem" the machine works fine! CompuNerd did an excellent job of recappiing and repairing this board when he had it. Things happen and I'm not blaming him for anything bad with the board. Who knows, it may have had this problem all this time and long before CompuNerd got it!
What you guys think - bad cap(s) or bad audio chip? This one really has my head scratching.
But this LC board still eludes me. At first I thought it was noise from the PSU. Nope. The PSU works fine and without noise on other LC Boards, including LC II, LC III and LC 475. So I decided to try a known perfectly working LC PSU from another LC III to this LC. IT SQUEALS!!!
So it's not the PSU creating noise on the lines.
But CompuNerd admitted long ago that he put one of the ROMs backwards on this board and killed the ROM. An honest mistake, we all done that at one time or another. So it took me a while to get a new set of ROMs, having to buy a complete set of 4 ROMs from ebay for $9. I replaced that 1 dead ROM and got the LC working again but it squeals heavily! Today I decided to replace the other three ROMs, and it still squeals but not as badly. Put back in the old ROMS and it squeals loudly. Replace the ROMs, and its quieted down but still squealing. Interesting...
So part of the problem is solved but it is still there. Like Schödinger's Cat being there and not there at the same time. So I'm thinking, could a replacement cap have blown at the audio section from the ROM being placed backwards? To me they look fine under a magnifying glass. Voltage is OK. The problem is that it continues to squeal.
Furthermore - with the ROMs replaced, it will quiet down after a long while (a 1/2 hour or so) to a white noise static background noise. Audio Amp Chip problem?
To make sure that it is not remaining cap goo on the board causing this, I have washed this board again and again.
Other than this "little problem" the machine works fine! CompuNerd did an excellent job of recappiing and repairing this board when he had it. Things happen and I'm not blaming him for anything bad with the board. Who knows, it may have had this problem all this time and long before CompuNerd got it!
What you guys think - bad cap(s) or bad audio chip? This one really has my head scratching.
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