"click"....hum...."click"....louder hum....repeat

[daz]

Yes, but like most or all the caps i have checked that already. I removed the chip today and checked pins 5 6 and 7 again as G1 said to do and the voltages there no longer fluctuate. So i guess i need a new TDA even tho i have tried a few. They must all be shot at this point, but the problem is i have yet to find anything thats definitely bad and i assume installing
a new TDA will just get me another blown one to throw in the pile.

That crappy schematic is absolutely unreadable.

That said, since you seem to have a problem with a TDA2052, which seems to be AC coupled (is there a cap in series with the input?) , I'd just concentrate on it and strictly follow the datasheet example.

So KRK will get angry because you don't respect their "creation"?

F*ck off KRK !!!!! , they should provide a readable schematic to begin with!!!!!.

So think you have a cheap EBay generic TDA2052 powered "1000W PMPO" board before you, and make it work following the factory datasheet, using its suggested values.

Won't even comment what I do in such cases.

[daz]

I just checked pins 5 6 and 7 on the HF side and it too is fluctuating. But if i check it's tweeter outputs it's NOT fluctuating and only showing .4VDC. So maybe DC fluctuation of a small amount (1VDC approx) on those pins is normal? I'll chck the cap at the input again as per your (Fahey) suggestion. Maybe i didn't swap it, only checked. Now i'll have to go thru all the detective work again to figure out which one that was ! Effin schematic......reminds me of marshall's schematics for thier 70'-80's stuff. May as well just thrown a can of paint on a canvas and called it a schematic.

[Jazz P Bass]

Simply for grins & giggles, would you be so kind as to measure the opamp supply voltages?

Pin 4 is -15Vdc & pin 8 is +15Vdc.
Also, while you are at it, measure the same point with your meter set to read volts ac.
I have a sneeky suspicion that one of them will measure something.(Vac wise)
Ideally, there should be ZERO volts ripple on the opamp supplies.

Aside: I just finished up a M-Audio Studio subwoofer.
Complaint: a low level hum & sometimes a very loud hum.

I found a bad -70Vdc supply cap, which caused the loud hum.

& a bad cap that 'fed' the +15Vdc voltage regulator.
This caused a ripple on the +15 volt opamp supply, which the opamps dutifully passed on to there output pins.
This was the cause of the low level hum.

[daz]

Pins 4 is just under 15VDC and 8 ia a volt less. If i try checking AC pin 4 has nothing but a fluctuation with a high of about 1/10 VAC and 8 was fluctuating wildly for a second or so showing 12VAC as the high point but only for a split second when i first put the probe to it then settles into the same as pin 4.

Simply for grins & giggles, would you be so kind as to measure the opamp supply voltages?

Pin 4 is -15Vdc & pin 8 is +15Vdc.
Also, while you are at it, measure the same point with your meter set to read volts ac.
I have a sneeky suspition that one of them will measure something.(Vac wise)
Ideally, there should be ZERO volts ripple on the opaamp supplies.

Aside: I just finished up a M-Audio Studio subwoofer.
Complaint: a low level hum & sometimes a very loud hum.

I found a bad -70Vdc supply cap, which caused the loud hum.

& a bad cap that 'fed' the +15Vdc voltage regulator.
This caused a ripple on the +15 volt opamp supply, which the opamps dutifully passed on to there output pins.
This was the cause of the low level hum.

[S2udio]

These are not rocket science.....pardon the pun !
Sounds like someones just got no experience troubleshooting.
Go to the data sheet and digest.....the TDA2052 is such a simple beast.
Any missing ground traces ?

[daz]

Geez.....it was a effin' solder joint ! I came to a point where i just couldn't cheack anything more, i'd checked it all. I had looked for bad joints a million times already and hit the ones that looked suspect at all. But i decided screw it, i'm hitting everything ! I hit about 20 or 30 of the most likely suspects and plugged it in a it works perfect. Crazy.

[S2udio]

Geez.....it was a effin' solder joint ! I came to a point where i just couldn't cheack anything more, i'd checked it all. I had looked for bad joints a million times already and hit the ones that looked suspect at all. But i decided screw it, i'm hitting everything ! I hit about 20 or 30 of the most likely suspects and plugged it in a it works perfect. Crazy.

Chinese lead free solder,gets all of us sometime or another.
Just fixed a computer PSU for a mate.
Intermittently dead when turning on from cold,only a year old.
Looked like it had been soldered by a ten year old (probably was)
Retouched the whole board,now behaves perfectly !

[J M Fahey]

Glad you solved it

Just for the record, maybe somebody will use this thread to repair his TDA2052 based amp, maybe I was not clear enough.:

That said, since you seem to have a problem with a TDA2052, which seems to be AC coupled (is there a cap in series with the input?) , I'd just concentrate on it and strictly follow the datasheet example.

I did NOT mean "concentrate on the input cap" but "concentrate on the TDA2052, consider it a generic amp and follow the (TDA2052) datasheet example"

The comment on the input cap meant that since it separates (DC) the TDA from the rest of the circuit, from there on you can analyze the TDA2052 on its own.
If you had asked, I might even had told you to lift an end of the input cap , to *fully* separate the TDA2052 "block".

Glad you found it , intermittents are pesky.
I always tell customers: "I much prefer an amp which is smoking, with cracked parts, than a seemingly innocent one which "works, sort of/most of the time, BUT ... " because they often show no problems on my bench ..... grrrrrrrr!!!!!!!

[daz]

I see what you mean now. I suppose that would be helpful if the component values are the same, but would they be? I'll remember that tho and check next time around. By the way, thanks to all for the help, i know it must be frustrating when you try and guide me and i don't do exactly what you say because i'm not a tech. But some of you just keep plugging away and i appreciate that. Special thanks to G1 and Jazz especially who always seem to go above and beyond in trying to help and for that i appreciate you guys very much. Thanks all. Anyways, i ran the thing yesterday for hours and left it on when i was aay just to be sure and it's solid. I don't have to tell you guys how often that happens. (a bad joint that you cannot visually tell even with a good magnifier light)

Glad you solved it

Just for the record, maybe somebody will use this thread to repair his TDA2052 based amp, maybe I was not clear enough.:


I did NOT mean "concentrate on the input cap" but "concentrate on the TDA2052, consider it a generic amp and follow the (TDA2052) datasheet example"

The comment on the input cap meant that since it separates (DC) the TDA from the rest of the circuit, from there on you can analyze the TDA2052 on its own.
If you had asked, I might even had told you to lift an end of the input cap , to *fully* separate the TDA2052 "block".

Glad you found it , intermittents are pesky.
I always tell customers: "I much prefer an amp which is smoking, with cracked parts, than a seemingly innocent one which "works, sort of/most of the time, BUT ... " because they often show no problems on my bench ..... grrrrrrrr!!!!!!!

[daz]

Chinese lead free solder,gets all of us sometime or another.

Ahhh...is that it? I never thought about it but maybe so, tho it didn't seem like it the way it flowed quick and easy with braid. But it never hit me that lead free might make for less reliable joints w/o visually looking like it.

[S2udio]

You also have to bear in mind,power monitor electronics take a hell of a vibration test .
Esspecially when given a hard time with the boom boom boys !!