Hi, guys!
By the way. I have the issue with Thump TH-15A - woofer doesn't work at all. HF speaker works.
What happend before. Power supply was broken and on the CON3 was +50V and -50V instead +28V and -28V. As a result blowed up C227 (47uF 63V). After fix power supply (replaced U102 TL431) on CON3 appeared normal +28V and -28V. HF cpeker start work but woofer doesn't. I replaced C227 and TDA8950TH - still no sound in woofer. I found that on woofer connector CON2 two pins are shorted between each other but not shorted to ground. Also on both pins is -28V. I don't know is it normal. When I switch on whole speaker I can hear click sound in woofer.
Can some one advice me how to fix woofer sound, please?

 

It is impolite to hijack someone else's thread. The thread belongs to the original TS (Thread Starter). Start a new thread and make a reference to the previous thread.

https://forum.allaboutcircuits.com/threads/tapco-thump-th-15a-amplifier-repair.138211/

 

Leave the woofer disconnected, your neighbors will be all the happier.

 

Leave the woofer disconnected, your neighbors will be all the happier.

It's good solution, but in two days I have party in my house and better if woofer will work at least one day

 

No one knows what the problem??

 

Does this circuit look similar to your amp..

 

here's the documents I got online

 

What test equipment do you have access to?

 

No one knows what the problem??

Does this circuit look similar to your amp..

View attachment 216904

No. Is similat to this

 

What test equipment do you have access to?

I am repairing mobile phones more than 10 years and i have all equipment needed for soldering and diagnostic. But I don't have any special equipment for diagnostic audio amplifier. Also I don't have experience in repair audio amplifiers. Thats why I asking professionals for help.

 

Can you scope the inputs and outputs and compare them??

 

Thanks for the info. It helps us in determining a good course of action.

I'd recommend checking all the supply voltages to ensure they are correct. Then check CN10 for audio or on the amplifier chip.

 

Power supply outputs:
CON3
1 +29.7V
2 GND
3 -29.7V

CON11
1 +14.8V
2 GND
3 -14.7V
4 GND
5 +3.3V
6 -26.9V (MUTE SIGNAL)

I am using this schematic

 

Then check CN10 for audio or on the amplifier chip.

Regarding CON10. Is it allowed to swap pins 2 and 4? In this case I can check is good signal on pin 4 and does woofer amplifier works.

 

Swap input signals to compare if you don't have a scope.

 

Yes, Dave is correct. Did you say the two output pins were shorted?

Review the datasheet to see how a single speaker is connected.

If your changing wires to inject a known signal, you should have not said you had all the diagnostic tools. The next person that I ask will have to tell me the make and model of all their test equipment they will be using.

 

Swap input signals to compare if you don't have a scope.

I swaped today input signals (pins 2 and 4) and situation is the same - HF speaker works and LF speaker doesn't. It means that both input signals are working and problem is in LF amplifier. I checked both speakers: LF has 6 OHM, HF has 4 OHM.

 

Ok so LF amp is at fault, have you checked the chip supplies , disconnected the speaker and can you measure the output voltages.

 

Deleted message

 

I did the measurement on the amp chip legs (TDA8950TH) with disconnected speaker and without input sound signal.

1 -25.3V
2 0V
3 28.8
4 0V
5 0V
6 5.5V
7 -21.2V
8 0V
9 0V
10 28.8V
11 0V
12 -25.7V
13 -25.2V
14 29.7V
15 -29.7V
16 -29.7V
17 -29.7V
18 -26.3V
19 -25.4V
20 -29.8V
21 -29.5V
22 -29.5V
23 29.7V
24 -25.4V