I have now an Asian design sound stream Picasso pca2.260
The amplifier don't turn on
I found damaged the 2 next transistors
I changed but the amplifier continue death
the voltages from the TL494cn
1 1.45
2 3.10
3 4.67
4 0.04
5 1.5
6 3.4
7 0.00
8 11.7
9 0.0000
10 0.0035
11 11.7
12 11.7
13 4.97
14 4.97
15 4.97
16 5.8
I need a little help from my friends
An externally hosted image should be here but it was not working when we last tested it.
The amplifier don't turn on
I found damaged the 2 next transistors
An externally hosted image should be here but it was not working when we last tested it.
I changed but the amplifier continue death
the voltages from the TL494cn
1 1.45
2 3.10
3 4.67
4 0.04
5 1.5
6 3.4
7 0.00
8 11.7
9 0.0000
10 0.0035
11 11.7
12 11.7
13 4.97
14 4.97
15 4.97
16 5.8
I need a little help from my friends
Pin 16 is being driven high. That's shutting the pulses down. Find what's driving pin 16. If it's a transistor, remove the transistor to see if the amp will power up and produce audio. Be careful because this will disable the protection circuit for the amp.
Greetings to all.
Thanks to Perry's tutorial, I found the diagram of the amplifier:
following clues I find the problem, the transistor Q208. KEM Part C3198, which is leaking.
This leaking part cause variation of feeding of Operational Amplifiers, activating the protection (see 16 and voltages on pin 3 of PWM) and sending DC to the audio output ....
When I remove it, everything returned to normal, now just put a new one.
Here is a bit difficult to get parts KEM.
Is there somewhere to help us with their equivalents?
Thank you very much everyone for your comments and help
Thanks to Perry's tutorial, I found the diagram of the amplifier:
An externally hosted image should be here but it was not working when we last tested it.
following clues I find the problem, the transistor Q208. KEM Part C3198, which is leaking.
This leaking part cause variation of feeding of Operational Amplifiers, activating the protection (see 16 and voltages on pin 3 of PWM) and sending DC to the audio output ....
When I remove it, everything returned to normal, now just put a new one.
Here is a bit difficult to get parts KEM.
Is there somewhere to help us with their equivalents?
Thank you very much everyone for your comments and help
Last edited:
That's just a generic schematic. It's the basic circuit used by many of the budget amplifiers (with slight variations). If you look at item 33 on the power supply troubleshooting page, there are several links to schematics for common circuits. Each one lists indicators that help you identify the type of circuit.
The part isn't going to be critical. Virtually any NPN transistor with the same pin configuration and greater or equal voltage/current ratings will work.
The part isn't going to be critical. Virtually any NPN transistor with the same pin configuration and greater or equal voltage/current ratings will work.
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