Failure-Recapping a MCS 3223

[sabalennon]

Short story: I tried recapping my receiver's power supply, it worked at first but the left channel died after I moved it a little, i opened it and noticed that one of the capacitors had gotten loose, I tried to reconnect it and now it won't power on.

Question: What could've caused this? Is there anyway to still fix it? I'm terribly heartbroken right now and don't want to do anything to it for a little while but I'm open to suggestions on what to do.

Long story: I had ordered 6 capacitors but only 3 of them were good enough for connecting (the legs were long enough for bending), I had taken all of them out before I got the new caps, so I put 3 of the new ones and resoldered 3 of the old ones. It worked wonderfully, I was very happy because the humming was completely gone and the sound was so much better. I tried using it with my turntable and moved it a bit and noticed that the left channel had suddenly died. I opened it and touched the caps and noticed that one of them was wobbly, pretty much lost all of the connections, I immediately opened it again and tried to resolder it, it was very tiring and stressful but I managed to do it, I connected it again and it wouldn't power on, but the capacitor was not wobbly, it was quite sturdy instead. Which leads me to believe that I messed something up while doing the second resoldering, or that the second soldering was even worse than the first one but how does that stop it from powering on?. I think I'm going to order the 3 capacitors that should've been there and put those in instead of the old ones and see if that fixes anything, but I would like some opinions on whether or not it's worth it or it sounds like it needs more complicated tweaking.

Emotional discharge: I feel quite heartbroken especially because it worked at first and it got me so happy and feeling accomplished, but it sucks to know that because of me trying to fix a small error that I caused I screwed everything up, I'm going to try and hold on to those small moments of joy that I felt when it was working, but right now I can't help but sinking in the failure.

 

[sruchris]

Can you post a photo of the area you worked on?

 

[coonmanx]

Calm down. Everything will be OK.

 

[Okke 70s]

Have you checked fuses yet?

You mentioned it was "very tiring and stressful" to re-solder that single capacitor, howcome?

 

[Racingh11]

A bad power supply won't effect just one channel. It is more likely that moving and working on it disturbed a dirty bias potentiometer causing an output transistor to short and then blew the fuse. Check the fuse and we can go from there.

 

[quaddriver]

give us a pic or two...is the 3223 one with discreet outputs, or stk modules? I have a 3224, 3225 and 3226 on my done list, and they flip back and forth. I think I have a 3223 in the
'waiting room' and if its the same, its not stk meaning we can walk thru a replacement.

what we want to see is some pics and then can you continuity test from where the leads come thru to board to the trace pads, to where they go - lets rule out a broken trace.

 

[sabalennon]

My bad, I should've added some pictures, here they are! I think I scraped some a piece of the circuit board, i don't know if that has anything to do with the lack of power, but i read that it's def a problem, I have ordered some new capacitors to put in there in case I can get a better connection with the long legs which is what I lacked the first time.

 

[Okke 70s]

Dude, don't get me wrong, but that is some awful soldering you did there Looks a lot like my first attempts probably. I'd recommend watching some u-tube on 'how to solder/weld' and practice...

You did catch the culprit thou. From what I can tell from the picture a piece of the track has come off and is likely not making proper contact anymore. You can test this using a multimeter (also referred to as a DMV) do you have one? If not, get one! You can get one for less then 20 cuddo's and it's the basic tool you can not do without when working on electronics.

So, when you got one: put it on the lowest resistance measuring lab. Then put the pins on to each other, and read the resistance (should be something like 0,4 ohm). Then put each pin on one end of the track you want to test, and see if you get a similar rating. If not: it's not properly making contact (or even at all).

Good luck!

 

[sabalennon]

Update: I have replaced the three old capacitors with new ones, this time having polished my soldering technique and actually using flux. Now it's working again! and a bit bette. However, now I'm noticing that the right channel sometimes gets louder than the left channel. Will make another post about it. Thank you all!

 

[Okke 70s]

Ah great! A bit of fluctuation in volume might be a poor contact on pod's, switches, connectors (or weldings). But hey, the important thing for now is that you got it going again!

 

[fromnowon]

i wonder what kind of soldering iron you're using. Looks like it's not getting hot enough for the solder to flow. If the copper trace gets damaged you can always use a jumper to get to a good spot. I've had to do it quite a few times actually . . . not ideal, but you can make it work. You can gently remove the coating over the copper with light sandpaper leaving a nice copper surface to solder to (one method).

 

[sabalennon]

Ah great! A bit of fluctuation in volume might be a poor contact on pod's, switches, connectors (or weldings). But hey, the important thing for now is that you got it going again!

Thank you so much. I have noticed that the imbalance is only there when the speaker switch is on A+B, so it might be a dirty pot, or some weird problem that one affects both seta of speakers... I'll give them a good clean and see!