Troubleshoot SMPS board with laboratory power supply

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

"because the guy said the main power supply is +/- 25v" Your power amplifier section used in you model does not use BI-POLAR (+/-) power supply like the one you have in the link. You can see that it only has one large filter cap in the secondary side. Your power supply has four set of rectifiers circuits. The Opamp sections needs BI-POLAR power supply and that is why it has +/- Voltage regulators.
Again, I do not who 'THE GUY' is, he needs to look at the board and see how you board is setup.

[int0x13]

Re: Troubleshoot SMPS board with laboratory power supply

The little cap next to b3 diode is a 50v 47uF cap. I think it may be 25v or -25v because the guy said the main power supply is +/- 25v but I don't understand why those 2 diodes are not close to each other are u sure its not the two big ones D30 and D31 in +/- 25v? If its like that I can use only one channel of lab PSU and all is good

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

You can use the +20V output to feed b+1 and the b+2, but the b+3 we do not know what that voltage should be, there should be a cap connected to that b+3, then you can estimate what the voltage should be

[int0x13]

Re: Troubleshoot SMPS board with laboratory power supply

I've found that page I don't think it talks about the same hardware but it has similarities:
http://www.thompdale.com/bash_amplif...1_bash_amp.htm
BTW I've tried to power supply the +20v and -20v on the 2 output diodes as u said and the regs are working:
I got on the output white J10 connector:
Pin1:20v
Pin2:-20v
Pin3 to 5:0v
Pin6:-15v
Pin7:0v
Pin8:15v
I was wondering why not use the same lab PSU channel to supply the +20 and the -20v (with 2wires in parallel of the 20v ones)? That would keep me one free channel for the main 25v right?

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

"I wanted to ask u how did u find out that the transformer had X number of output voltage ?" By tracing out the connections to the rectifiers and many many many years of experience.

[int0x13]

Re: Troubleshoot SMPS board with laboratory power supply

Yes in EU version 220v there is 2 filter cap in parallel that's I think the only diff between EU version and us version. That's why I considered buying a spare us amps and solder one filter cap but I didn't find any spare amps plate. That's why I tried to repair the board although I think it wouldn't work because of the bad shape of the PCB.
About supplying the secondary my bench PSU has only 2 Chan+1 aux 1-15v so I miss one in any way. The original guy said only 2chans is enough. Anyway ty for help. I wanted to ask u how did u find out that the transformer had X number of output voltage ?

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

Yes, I did read the previous, you will need 4 power supplies: +25VDC (Negative of this power supply will be connected to the circuit ground) for the B+1 for running the power amplifier section..
+20VDC (+ connected to the B+1, Negative connected to the circuit ground) for for the B+2 for feeding the +15V regulator, -20VDC (Negative connected to the B-1, Positive connected to the circuit ground) for the B-1 for feeding the -15V regulator.
The B+3 will be the problem one since we do not know what voltage for that will be.
This amplifier is Class D Bridge mode to run off the single power supply instead of from BI-POLAR power supply like the shown in the SCH in the link.
BTW, the pictures you posted (post 1) only show 1 main filter cap. Are the two caps connected in parallel?

[int0x13]

Re: Troubleshoot SMPS board with laboratory power supply

Yes, but this power supply is not standard as there are some resistor and a fuse between the bridge and the 2 main filter caps, and also 2 yellow X cap (the ones just between the daughter board and the filter caps).
https://www.dropbox.com/s/r5548uni2e...72603.jpg?dl=0 and here http://i.imgur.com/L14Q8.jpg
I think this board is good for the garbage too, but before id like to try the trick with my lab PSU on the secondary side. Did you read my previous quote:

I translated from French forum where the guy talk about that it is source person that gives me the idea. Unfortunately I can't contact him he don't answer here it is:


To raise doubts about the functioning of the amplifier , using two conventional power supplies , I have supplied the power section on the + and - less of the diodes in secondary rectifier in + and - 25v and the other power supply in + - 15V on the outputs of the 7815 and 7915 , and the Ov on the - of the speakers. Power supply section first 25v, then second 15V power supply . The amp and preamp / filter function normally.
I 've set the level and extent of the outage of the power supply

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

The board looks like it is beyond repair, since I do not have the board in front of me, I think the Negative of the Bridge should have connection to the Negative of the main filter cap, the Positive of the bridge should have connection to the Positive of the main filter cap.

[int0x13]

Re: Troubleshoot SMPS board with laboratory power supply

Seems like there is no EDIT in this forum?
here is my current situation:
http://xfaktor.free.fr/20140924_170711_comments.jpg

[int0x13]

Re: Troubleshoot SMPS board with laboratory power supply

I translated from French forum where the guy talk about that it is source person that gives me the idea. Unfortunately I can't contact him he don't answer here it is:

To raise doubts about the functioning of the amplifier , using two conventional power supplies , I have supplied the power section on the + and - less of the diodes in secondary rectifier in + and - 25v and the other power supply in + - 15V on the outputs of the 7815 and 7915 , and the Ov on the - of the speakers. Power supply section first 25v, then second 15V power supply . The amp and preamp / filter function normally.
I 've set the level and extent of the outage of the power supply

Maybe you can better understand like this but for me its not enough precise would need a little pic or schematic
I've tried to power up the amp and fuse burnt instantly
I've changed the filter cap and both switching MOSFETs and checked diodes bridge

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

The diagram you provided does not use switching power supply, it uses linear power supply, so it is not even close to what you have.

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

"The regs are 7815 and 7915."
7815 is the 15V Positive Voltage regulator.
7915 is the 15V Negative Voltage regulator.
"Somebody told me i should put 25V on the diodes first then after supply the regs with +15v and then the amp should work." Which Diode? You need -15V also for the Opamp to work. An you will need the main Voltage 25VDC? for the power amplifier section.
If you only supply the 25V, how is the Opamps are going to work without the Negative 15V? It sounds like someone did not understand the circuit or never really try it out.
Why don't you try to see if the power supply is putting out any DC at all first before trying to do something that will cause the damages or more damages than what it is right now?

[int0x13]

Re: Troubleshoot SMPS board with laboratory power supply

Im currently trying to repair the cut tracks before i try to switch on. Ive managed to find out another kipsch service manual, you can see on page 18 the primary side of the amp here:
https://cdn.badcaps-static.com/pdfs/...327121b6a0.pdf
The regs are 7815 and 7915. Somebody told me i should put 25V on the diodes first then after suppy the regs with +15v and then the amp should work.

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

Did you also check the DC Voltage at the test point as shown in pic# 2? and did you check the fusible resistors?

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

"What is b-1, b+1, b+2, b+3 ? It is rectifying diodes, normally there is 4 of them. You say to put the bench power supply on those diodes point? " There four outputs (3 positive supplies, and one negative supply) from that power supply, the problem is to figure out what the Voltages should be at those output side of the Diodes.
Those two regulators, one should be for the Plus and one is for the Minus supply for the Opamp to operate. You should look at the P/N as printed on the body of those two regulators. Since I do not have the board in front of me to look at, I assume they are regulator ICs.

[int0x13]

Re: Troubleshoot SMPS board with laboratory power supply

Excuse me but i dont understand what you mean on the photo1?
What is b-1, b+1, b+2, b+3 ? It is rectifying diodes, normally there is 4 of them. You say to put the bench power supply on those diodes point?
About the regulators i know i should put +15v on the output, but on each chip or only one? And the ground on the regulator ground?
Can you detail a bit more, its the first time i try this experience i dont wana make mistake.

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

OK, some test points to test. There are many power supplies in the secondary side.
Be careful when test the Voltage in the primary side.

[int0x13]

Re: Troubleshoot SMPS board with laboratory power supply

Here you are
https://dl.dropbox.com/s/u1tti1r6syy...13556.jpg?dl=0

You can find some high rez pictures here as well:
http://forums.extremeoverclocking.co....php?p=3774040

[budm]

Re: Troubleshoot SMPS board with laboratory power supply

Pictures of the bottom side of the board so we can trace out the connections of the secondary side of the transformer to see how many output windings it has?