50mf231d/37 Power supply repair

[Vizor]

50mf231d/37

1. Bought this from a guy that was trying to repair it and screwed it up pretty good.

2. they are capacitor slots.


how can i repair this if i can.

[awyatt2]

Re: 50mf231d/37 Power supply repair

you need to remove enough soldermask to the trace where the caps led to, then tin with solder put cap thru hole use a glue to place them such as electronic silicone, don't need much just a dab. wrap a wire around each lead and solder to cap and other end solder to where the pad went on the trace.

[Vizor]

Re: 50mf231d/37 Power supply repair

any videos or anything showing how to do this i am so clueless never had to do it before.

[selldoor]

Re: 50mf231d/37 Power supply repair

There are lots of videos on youtube. For this particular job I think this one is OK
http://www.youtube.com/watch?v=2hpHez1I2rc
Use the wick to clean off excess solder but do not overheat the board.
Clean up the area with isopropyl alcohol.
Perhaps post another pic when you have done that and we will be able to see better
if the trace is broken/burnt or just covered in flux.
There is no need to glue down the capacitor you can either hold them in place or
bend the legs slightly apart to hold them while you solder. Do you know the value of the caps to refit? or is that something we will have to research.

[Vizor]

Re: 50mf231d/37 Power supply repair

the pics i posted have been cleaned and thats about all thats gonna happen in that area.

[vinceroger69]

Re: 50mf231d/37 Power supply repair

have you got a link to the power supply diagram so we can see where the capacitor tracks go to the right hand side cap is easy the positive side should be ok to resolder to the negative side i would join to the track that you can see above the through hole in the board. the left hand capacitor again it looks like you can resolder the positive side ok but not sure if the negitive lead goes to the large thick track underneath? it does lok like it but not 100% sure. i got to say i have repaired worst.

[selldoor]

Re: 50mf231d/37 Power supply repair

OK This is my suggestion for the repair. two of the joints look ok so solder them first to hold it staedy and cut off the excess wire so it out of the way. On C0859 get a small piece of preferably insulated wire and either make a loop on the end and slide down the leg or wind it around the leg of the cap and solder in place. Cut to length and solder the other end to the next joint along the trace - looks like that smd ceramic but you can check.

On the C8060 I cant see that there ever was a trace - is it a double sided board with a trace on the top?
(Can we have a picture of the top.) Anyway try and run some solder down the leg through the hole. When we see the other
side will advise further.
Do you know the values of caps to fit?

[vinceroger69]

Re: 50mf231d/37 Power supply repair

i personaly think in the above pic the first pic the puple outlined part the track would of gone down to the thick track. as selldoor suggests a pic fro the top would be great or a link to the power supply diagram.

[Vizor]

Re: 50mf231d/37 Power supply repair

2200uf 16v

[selldoor]

Re: 50mf231d/37 Power supply repair

Well it is a double sided board so my opinion (no Guarantee)is that it doesnt have to go anywhere on the back, but you need to make certain you have connectivity front to back, hence the need to get the solder to run through the hole. You can check continuity between the leg and the joint of the leg of the other cap as both go to the same trace.

[vinceroger69]

Re: 50mf231d/37 Power supply repair

i agree with selldoors above post now we see its a double sided board its joined on the top side as both the negitive terminals of the caps are on the same trace.
i totaly forgot there double sided on boards.

[mariushm]

Re: 50mf231d/37 Power supply repair

Pretty much what was already said.



If you want, for extra hold, scratch away the insulation on the pads where the yellow rectangle are.

Put the caps through and bend the leads so that you can solder a bit of the lead in such a way solder will go through the hole a bit and also solder the end of the lead on the copper pad.

On the bottom left capacitor hole that's gone completely as far as i can see, you could go on the other side, scratch away the insulation for a bit, then grab a thin piece of uninsulated wire and solder its end on that copper pad on top.
Now put the wire through the pad along with the capacitor lead and solder on the other end. Optionally, you could also use a bit of wire to solder the lead to the negative lead of the capacitor above.
Put some electrician's tape over everything so it won't sag and touch the metal case.

[jhd2112]

Re: 50mf231d/37 Power supply repair

Maybe try some silver flux, heat capacitor lead wire about 1/4 inch down leave lump of solder on wire leads then insert capacitor, from uderside of board (capacitor facing up) heat lead wires and solder will drop from top down. Let cool then flip board over and solder feet in, then check with multimeter. Hope you get it done. Good Luck

[kca]

Re: 50mf231d/37 Power supply repair AND similar issue w/ 50PF7220A/37 PSU board

Hello everyone ~

Not sure if any of you are still here since 2012, but I wanted to first thank you for your detailed posts back then. They are helping me to solve a problem that is extremely similar. I just posted a new thread about six hours ago, but have cut and pasted it here in the hopes that one or more of you might be able to comment. Here is that original post from a few hours ago:
_______________________________________________________________
Hello all ~

I am working on a PSU from a Philips 50# (50PF7220/37) plasma and needed to replace two bad caps at the bottom center of the board. I went at it too aggressively and ended up taking one pad off completely and another one nearly off. Hoping to get this back in order before proceeding any further.

BOTTOM OF BOARD:
If you take a look at the pic of the bottom of the board, you'll see (counting from the left) the first pad that is still there, but hanging to the run somewhat precariously.

The second one looks to be in tact still.

The third is the one I'm mostly concerned about, as this is the pad that came completely off (I still have the pad, and it's fully intact (i.e. circular)).

The fourth one seems to be in tact just like the second.

Looking for some expert advice on what I need to do to repair this before installing the two new caps (3300uf 10v 105 degree). Specifically, here are my questions:

1) Will I have to drill hole #3 and put in some kind of funnelet and then attempt to reattach to the trace run? Or, as is my hope, is there an easier way? As I mentioned, I still have the in-tact ring pad and that can simply be dropped back into the blackened hole. But, just soldering that back into place does not seem like it will make the proper connection to the run.

2) Given the type of board it is, do I need to be concerned about repairing both the bottom pads/traces, or the top, or both? I read a few forum posts that indicated I might be able to ignore one or the other, but could not make complete sense of that advice.

3) Can hole #1 simply be soldered after the new cap lead is dropped through? It is still attached to the run, but the ring itself looks like it might be compromised. Will the solder fill in any gaps and form a proper connection?

4) Do holes #2 and #4 look like they can be left alone?


TOP OF BOARD:
Also, I have included a photo of the top of the board too. Here, one of the small copper rings came off during the desoldering process and was lost. I am wondering how imperative it is to find or replace that before installing the new cap.


I plan on following the advice you provided back in 2012 to attempt this repair myself. Is there anything from my pictures that would give you reason to suggest anything else before I begin?

Thanks in advance for your replies / advice.

[RCA2000]

Re: 50mf231d/37 Power supply repair

One thing to remember..is this is a DOUBLE--SIDED board.. anfd so connections come form BOTH SIDES of the board. I see that on the FOIL side...there is a cap with NO negative connection to it--it comes from the OTHER side of the board. SO...take a piece of wire and solder it to the NEGATIVE pin on the cap..solder the OTHER end of that wire to the TRACE...that went to the pad that was there. THEN..put the cap through the board and solder the POSITIVE lead..normally to the COMPONENT side of the board. This should work for you. Secure the cap with a bit of silicone whe done.

[kca]

Re: 50mf231d/37 Power supply repair

Hello RCA2000 ~

When you say there is a cap with NO negative connection to it, do you mean C8048? If so, then soldering that piece of wire between the negatives on C8048 and C8060 seems to be what mariushm was suggesting in his post above from June 4, 2012. Can you take a look at the picture he posted back then (with the yellow boxes and red lines), and see if that makes sense to you as an overall approach?

On mine, it seems like what I need to do is to make the negative to negative connection I just described above, but also to ensure that there is a top to bottom solder connectivity by getting enough solder into the through hole.

Also, do you think C8059 on mine can simply be soldered per usual one the cap leg is put through, or is that negative ring pad too damaged to do that without some repair work as well?

[RCA2000]

Re: 50mf231d/37 Power supply repair

Looks like the negative leads of 8060 and 8408 are tied...so YES..looks like you CAN do that,.

on 8509...it looks like it is connected to BOTH the top AND Bottom of the board on the negative side.. SO...take a DMM..and OHM...from the TOP of the board..to the BOTTOM of the board..and see if they show shorted if SO..it IS ok...to simply put that cap back in..and scrape some coating off of the bottom trace...add solder...and solder the lead to that.

if it does NOT show shorted...THEN you have to run ANOTHER wire...to connect the top negative to BOTTOM negative connections.

[kca]

Re: 50mf231d/37 Power supply repair

I did as you suggested and my DMM read shorted (i.e., it sounded) on all of the following top to bottom connections:


C8059 top of board positive to bottom of board positive. This sounded as shorted as expected.


C8059 top of board negative through to the bottom of board negative.
(So, despite the partially damaged ring pad, that one looks like it can be soldered as you suggested in the last post. Is it still best to scrape some coating off of the bottom trace even though the DMM sounded every time, then bend the cap lead in that same direction? If so, I assume you mean to scrape a bit off in the downward direction where the trace clearly leads down out of the hole.

______________ ______________ _____________

C8060 top of board positive to bottom of board positive. This sounded as shorted as expected.

C8060 top of board negative through to the bottom of board negative.
(Here, somewhat unexpectedly, I also got the sounded short signal when I stuck the DMM probe deeply enough into the through hole to apparently make contact with some conductive material. So, I was glad to see I hadn't damaged that in full. Next, I took the in-tact ring pad that had come off of this burnt hole (I had saved it during the desoldering process), and laid that gently on top of the burned area. When I tested again with the DMM, this time I only laid the probe on top of the loose ring to see if it was making contact with the metal in the through hole and it was. The meter sounded short with this method as well.

So, in regard to the badly damaged C8060 negative on the bottom of the board, can I simply fit that small ring pad over the cap lead once it is in and then solder that whole joint fully, or should I scrape the board and bend the lead as we discussed earlier just to be more sure?

[RCA2000]

Re: 50mf231d/37 Power supply repair

As long as you make sure you get a GOOD connection..between the top and bottom points...all should be ok.

all else sounds good. Good job. And yes--go ahead and scrape a bit of coating form that trace towards the bottom--to insure a secure connection.

[kca]

Re: 50mf231d/37 Power supply repair

Great! Thanks for your help, RCA2000.

I thought I would try to utilize this suggestion from a poster back in 2015 that read as though it would likely help to ensure the through-hole connectivity we are seeking:

Maybe try some silver flux, heat capacitor lead wire about 1/4 inch down leave lump of solder on wire leads then insert capacitor, from underside of board (capacitor facing up) heat lead wires and solder will drop from top down. Let cool then flip board over and solder feet in, then check with multimeter. Hope you get it done. Good Luck

Do you have any thoughts on that? I am not sure about the silver flux part. Do you think he means to coat the cap lead with this? Is that necessary, or could I just heat up the cap lead a bit and leave the lump of solder to flow down the cap lead leg as I insert it?

Do you happen to be subscribed to this thread, RCA2000? I would really like to be able to write to you again for advice if I have any other questions that arise before my new caps arrive in the mail, and perhaps as I am doing the actual repair if things start to go awry in any way. You have been extremely helpful and I appreciate your expertise. I've only been doing this for a couple of weeks now, but learning rapidly thanks to folks like you.