Sony D-121/125 repair

Convoy

I've tried to repair three 121s and one 125 so far. These players all have horrible SMD caps that all leak and are nearly all dead. THT caps seem to measure reasonably well with an in-circuit ESR meter. Usually the headphone out is dead and the player only reads discs sporadically, often powers down. I had zero success with cap replacements so far. I'm reasonably thorough. I remove the existing caps, remove any leakage with solder and flux, remove the solder with wick, clean with IPA. The I inspect the pads with a microscope and verify continuity to nearby connections. I use high quality flux and solder. Check every cap with an EST meter before use. I run bodges for all bad pads, traces and vias I can find. My latest attempt with a 121 also did not go well. The player only worked sporadically, only sound from the line out. After replacing all SMD caps in the power and digitial sections the headphone out started working with some heavy crackling now and then and the player started working a bit more reliably. Eventually the headphone out stopped working again. I replaced the caps in the audio section as well. Headphone out worked for a few seconds, the went silent. Player then started exhibiting power down and startup issues, doesn't work any better thn with the broken caps. I tried my best to fix anything damaged I can see and make sure all the replacements are soldered in properly, same footpring, orientation, sufficient voltage and same capacity. This has been my experience in general with these players, recapping seems to give some initial improvements but they all revert back the broken state they were in initially. What am I missing doing wrong?

kaosun

Usually I will replace ALL onboard SMT caps, clean the motherboard with ultrasonic cleaner by IPA. Your issue seems like there are issues of vias. It's quite common to see vias are broken from top layer to bottom layer of PCB. Sometime if the vias are hidding under chips, you cannot easily find it. Therefore, you'll have to analize the circuit to locate where are the broken points. It takes some time but you should be aware of that each player was tested working when they were made. For sure, each player can be finally repaired.

Convoy

I replaced all SMD electrolytic caps in all four 120-series players I tried to repair. I unfortunately don't have an ultrasonic cleaner, have to do it manually with IPA, brushes and Q-tips. I think I must've missed a damaged via then! I successfully repaired a D-NE511 that was severely damaged by battery acid, had to run quite a few wires to fix broken vias and traces.

One Issue I have with the D-121 is that I don't have a matching schematic / board view for the players I encountered. My service manual has several revisions of the PCB already but the ones I encountered in the wild had even more different board revisions. The layout of the caps etc. looks quite different between the models.

Hm, I tried my best, but I must've missed some more corroded connections...

kaosun

Yep, can you soak the PCB to IPA for a while in case the leaking still exist under some chips.