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Old 22nd February 2012, 11:08 PM   #1
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Default Pioneer GM-X574 trouble amp

Hi all.

I have a Pioneer GM-X574 4ch car amp that's giving me the silent treatment.
No sound from it but seems ok. All transistors give correct readouts but there are 4 DMOS that I am not sure how to test.
I found the datasheet on them here:
http://www.datasheetcatalog.org/data...cs/mXqwvzw.pdf

The capasitors looks like new so not sure what's up. Also the red diode is blinking.
Manual doesnt say what that means, but I guess it's because it's not working

Anyone have any idea what I should check next?
Only have a 0-5v scoope here but will try to get a better one this weekend..

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Old 23rd February 2012, 04:11 AM   #2
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Are the amplifier ICs TDA7294? Try to get the datasheet and check their mute/standby pins. The amp is probably muted because protection is being activated.
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Old 23rd February 2012, 08:25 PM   #3
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Yes the ICs are TDA7294. Both pin 9 (std by) and pin 10 (mute) have about 6 volts on them.
Power to the ICs are 11-13v oscillating (pin 13-15).. I guess there should be higher voltage here?
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Old 23rd February 2012, 08:35 PM   #4
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Think the power source is dead...
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Old 23rd February 2012, 09:34 PM   #5
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PIONEER GM-3000T Bridge Able Amplifier

Here is a amp that is "close" to the one I have. Same ic for controll. PC494C and PA2027A.
The PC494C doesn't get VCC power on pin 8,11,12.
emailed Pioneer if they could send me a service manual for the amp...
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Old 23rd February 2012, 10:44 PM   #6
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Quote:
Originally Posted by Turbofun View Post
Yes the ICs are TDA7294. Both pin 9 (std by) and pin 10 (mute) have about 6 volts on them.
Power to the ICs are 11-13v oscillating (pin 13-15).. I guess there should be higher voltage here?
Turbofun,
according to the DS and application schematic, when measured against pin 4 (GND), pins 7 and 13 should have from +24 to +36V, while pins 8 and 15 should have -24 to -36V.
If you are seeing the supplies oscillating (how fast?) at a lower voltage, this could be due to an overcurrent protection shutting them off, then on again etc.
possibly indicating a broken TDA7294.
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Old 24th February 2012, 10:11 AM   #7
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Got 5-6v on those legs, power is going up and down within a second.
Pioneer emailed me the service manual today so got something to look at now.
Ordered some new components so we'll see when they arrive.

I'll upload it here since it's not to be found on the web:

link removed

Last edited by wintermute; 24th February 2012 at 10:23 AM. Reason: remove link to service manual.
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Old 24th February 2012, 10:25 AM   #8
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Hi turfobun, it is great Pioneer emailed you the service manual. I've removed the link to the upload, as they may not be happy about that, and the next person who asks for one may not get it if they feel people are making their copyrighted material available. You should probably take that upload offline.
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Old 24th February 2012, 10:39 AM   #9
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Aha that's probably why I didn't find the manual on the web. hehe
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Old 3rd November 2012, 11:32 AM   #10
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Are there more such car audio/car hifi power amplifier models in the marked equipped with TDA7293/TDA7294 ?

I am looking for such amps in damaged/faulty condition to carry out various experiments with outdoor power supplies.

Thank you for advices.

P.S.
about
TDA7293/TDA7294 - by which commercial integrated Stereo Amps in use ?
I have listed all components equipped with TDA7293/TDA7294, which I have found until now.

Last edited by tiefbassuebertr; 3rd November 2012 at 11:36 AM.
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