Attempts to fix 3.5mm audio socket on Sony D-33 Discman

I bought this D-33 with a known issue of no audio out the right channel via headphone jack (line out however is fine), having opened it up I noticed a hairline crack on the top layer of the PCB, under what seems to be the ground pin of the headphone socket, I added a small bodge wire where I had tested there was continuity issue (only when a jack was inserted). This did not resolve the right channel being missing?

Then I noted when you start to pull the plug out, you suddenly get audio in both L & R, but I'm assuming this is just a single channel being pushed to both L & R headphones.



I mapped out where everything connects below, does it seem correct that L channel is connected to 2 pins?

I have not been able to get to the other side yet, as multiple wires need desoldering to access it easily.

Is this most likely symptoms of a broken connection I've not yet found, or broken socket? should I just wire in a new headphone socket to what I assume is the L & R channels + ground on the back of the existing socket, to rule out broken socket maybe?

 

Clean inside of 3.5mm socket with alcohol on a cotton swap (Q-tip) that has been stripped down to fit. Remove the heavy oxidation that is bound to be there. Then I would just fully re-flow the solder pads. And see what that does first.

 

Initially tried reflowing and that didn't bring the right channel back.

Finally resolved this when I found a crack just under the the right solder connection for the 3.5mm jack, traced back to the source pins on Bass Boost amp IC304 to check both left and right were working, found the via right next the pad which was also outputting signal. So just scraped some solder mask, and tacked on a little bodge wire, and she's back to stereo.



https://archive.org/details/manual_D33_SONY

 

Urgh now the damn thing is skipping and just plain crashing out of songs half way through with garbled noise, I'm assuming given these were from 1991 ish, the 34 year old capacitors can't be doing so well! and may have something to do with odd behaviour.

Counting the electrolytic caps I can see 44 of them! I haven't pulled up the pcb to see underneath but I'm assuming only a few will be the radial one's? presumably the higher capacitance/ higher voltage?

Which one's are best to focus on?

https://archive.org/details/manual_D33_SONY

 

Maybe just the headphone coupling electrolytic capacitors that are directly on the 3.5 headphone out jack. Otherwise, yeah, this one has a lot of capacitors. (I think the D9 and D-99 have even more... Vs the D-35 with 12 and D-555 with 7 for example. Funny how some models have so few while others have about 50 Different design teams and design philosophy perhaps? )

 

Here is the backside of D-33: all original ELNA and Rubycon caps are good. The only 'fix' here is 330uF headphone coupling capacitors instead of the original 100uF. Of a few dozen (yes, as multiple of twelve!) D-33/34/36 Discmans that I fixed over the last years, only D-36 had a problem with electrolytics. Actually, with just one electrolytic - C524. For some reason Sony decided to use SMD instead of a thru-hole for C524 in D-36... with the same result as with most SMDs of that era

In short, the most probable cause of your D-33 problem is elsewhere, NOT bad caps

There are two serial killers for D-33:
1) Leaking batteries damaging mainboard
2) Broken or 'tired' laser mechanism

The 1st one is easy to detect, just flip the mainboard and see if any battery damage there

Laser Sled mechanism: First check if metal plate is not touching laser, use strip of paper. dentists do something similar
To check the gears you have to remove metal top plate
here it is, one of the gears has a broken tooth:




if all gears intact, then check that gears engage with laser strip when laser all the way In and all the way Out. If not, two screws allow for the adjustment


and since you already went this far, it is always a good idea to pop-up the shell and gently clean laser optics:


Good Luck!