ADT2 Studio Monitors TDA8920BTH Help

Thread Starter

Dirtynut

Joined Jan 2, 2020
2
Hi everyone, I’m new to to forums and would like to thank in advance everyone who is willing to help.

I have a pair of studio monitors (speakers) And one of them started to sound as if the speaker was blown, I took the amps out of the speaker that sounded blown and upon further inspection i noticed that a capacitor had blown off as you can see in the picture. I have no idea what value this capacitor is supposed to be(based on PDFs for the 8920bth seems like 100nf), The amps is a three channel design but is only being used for the lows. I know there are some very smart people on these forums and I was hoping someone could help. I’ll list what I’ve tried and what I’ve observed below:

Tried amp from working speaker on speaker that sounded blow and everything sounds fine.
Took capacitor circled in yellow and replaced blown capacitor circled in red (didn’t work)
Tried different value capacitors and now the display on the back of the monitors says amplifier error (might have damaged good capacitor as well).

The pad is f’ed up so I’ve attached wires so I can test different caps without constantly soldering and unsoldering. As far as the chips one chip is a TDA8920BTH and the other is a TDA8922BTH but it seems as if the 8922 was bypass or not used from the factory as there is two other separate amps for the mids and highs. The funny thing is even with the blown capacitor it was working fine except the low end sounded like the coils was fried and only at higher volumes, but since I’ve taken the capacitor off of the 8922 and used it on the 8920 side now the rear display just says amplifier error. The voltage coming into the unit is 27v +/- and the voltage across where the cap is supposed to be is 54v according to my meter.

Some more pics. Thanks for the reply

Thanks in advance to anyone willing to help.
 

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Dodgydave

Joined Jun 22, 2012
11,306
Here is a photo from the datasheet showing the values for a 100W circuit,, check the capacitors to see if it matches your pinout..I think its on the output pins,21,22,23,24,,, out2 Boot2, so its C27, C37 to 41..


TDA8920B.jpgTDA8920B-pinout.jpg
 
Last edited:

Thread Starter

Dirtynut

Joined Jan 2, 2020
2
Here is a photo from the datasheet showing the values for a 100W circuit,, check the capacitors to see if it matches your pinout..I think its on the output pins,21,22,23,24,,, out2 Boot2, so its C27, C37 to 41..


View attachment 195887View attachment 195889
Thanks for the reply and the diagram, the cap that blew was across pin 20 and 23 so Vssp2 and Vddp2. So if I am right the circuit shows a 100nf cap?
 
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