Charlize dead?


2008-02-22 10:02 pm
HELP, I think I killed my beloved Charlize!
I powered her up from the 12 volt supply of my computer possibly creating a ground loop.
Now I have 12 volts on the speaker terminals of one channel, the other is still working OK.
Is she dead or does anyone know a way to revive her??
A ground-loop rarely kills chips. 12V at one output while the other still works is a bad sign. Try removing all power from your Charlize and measure from each to the two output terminals on the channel with 12V, to the 12V supply terminal of the Charlize, with an Ohm-meter. If you have less than 100 Ohm the TA2020 chip is most likely dead on that channel.
Revival in such case means changing the TA2020 chip.
Hi Hoka,
It is partly good news that none of the output lines seem to have shorted to the supply rail or the ground rail. This way, and from the fact that you can play music form the other channel, we can investigate the defect channel with "power on".
Normally, all output lines should measure close to the same impedance to the supply pin (pins 22 and 25) and the ground pin (pins 19 and 28).
Why you measure 18.6K against 2.5K I cannot say.
On page 5 of the datasheet ( ) you have a block diagram of the TA2020. Can you tell me if it is the upper or the lower channel that is defect?
When you play music in the good channel, do you have any sound from the speaker on the defect channel? Does anything get hot in the defect channel?
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Hey, for a second I thought you meant beautiful:


Hi Hoka,
Top-one means input pin 10 and output pins 24 and 26.
You are right, it is not clever to work with an amplifier having a DC on the output and still use the speaker as test-load. Do you have a resistor, hopefully 2-5W and in the range 50-1000 Ohm we can use as load for test? Without any loading, you risk that even a functional channel will not settle correctly DC-wise after start-up.
When the dummy load issue is settled we need to check the static working values.

I can see Mr. Fahey has managed to find the front of a spec-sheet. Starts looking really interesting.