68kMLA Classic Interface
This is a version of the 68kMLA forums for viewing on your favorite old mac. Visitors on modern platforms may prefer the main site.
| Click here to select a new forum. | |
| Performa 575 Board, no sound, cap + short to ground? | |
| Posted by: protivakid on 2022-08-03 15:20:56 Have a 575 board here and the audio stopped working, system power-on sound, internal speakers, and both headphone jacks, nothing at all. Looking at the board I can see the SMD component at L2 has leaked. It reads 101 which I believe this is a 100μH inductor but PLEASE correct me if I am wrong. I was planning to re-cap before I saw the inductor but I also noticed the + side of the top cap closest to the expansion is shorting to ground... guessing this isn't correct and not sure if it means there's another problem as well. Q1 - Can anyone with a good 575 board confirm the positive side of that cap does NOT short to ground? Q2 - Can anyone confirm the L2 inductor value and correct package so I can order a replacement? | |
| Posted by: protivakid on 2022-08-09 08:46:12 I thought this board had some life in it but perhaps not. Anyhow to those finding this thread down the road, a fellow user was able to confirm that the + cap pad I marked does indeed short to ground on his board as well. He also sold me two 101 inductors and with them I was able to restore audio to this mac. | |
| Posted by: Phipli on 2022-08-09 09:09:07 Note that the sound circuit has positive and negative voltages, so where you see the + connected to ground may be the cap between -5v (??) and gnd. In that case gnd is the higher voltage. I've got dead sound on a 630 board, not had a chance to work on it lately. Performa 630 DOS - No AudioHello folks! I've been tidying up a Performa 630 DOS Compatible that was found at a dump a good few years ago, it has some corrosion damage due to being left outside (rust on ports, couple of corroded pins on the processor, some relatively minor blemishes here and there, plus it looks like the...
68kmla.org
There is a short somewhere and I've removed the DFAC II, some caps and the negative rail regulator and not found it yet. More effort needed! | |
| 1 |