Hi all,
I have an aer compact 60 that stopped working mid-gig. The TDA7294 had blown, thinking that was the issue we replaced it and it blew again. After measuring voltages we're measuring 73 volts to the TDA7294, considerably out of tolerance for the amp chip. We replaced both 35 volt 4700 uf capacitors but voltage is still measuring 73V. The unrectified voltages are 27 volts on each side, any ideas what might be happening?
I have an aer compact 60 that stopped working mid-gig. The TDA7294 had blown, thinking that was the issue we replaced it and it blew again. After measuring voltages we're measuring 73 volts to the TDA7294, considerably out of tolerance for the amp chip. We replaced both 35 volt 4700 uf capacitors but voltage is still measuring 73V. The unrectified voltages are 27 volts on each side, any ideas what might be happening?
Would have to see a circuit but the chip itself is specced for 80 volt operation. That means the voltage as measured between pins 7 and 8 and between pins 13 and 15. Depending on the design of the amp each pair grouping may see different voltages but neither pair should exceed 80 volts.
Thanks Mooly for responding. We replaced the chip again and it blew straight away. I'm not with amp at the moment now and AER don't give schematics. The two TDA7294's we've tried were cheap (£4) and info we found say they are rated for between 10v and 40v hence we were thinking there's a problem with too much power running into the chip. Are there better quality chips that can cope with the voltages you mentioned?
First thing (if you did this) is never buy parts like these from ebay. Too many fakes around. Always buy from authorised distributers. There are two physical types, V and HS which are vertical and horizontal mounted.
Date sheet:
TDA7294
You could try CPC in the UK, the illustrations are just, illustrations and do not show the difference.
https://cpc.farnell.com/stmicroelectronics/tda7294v/amp-audio-100v-100w/dp/SC08456?st=LDL104R/S
https://cpc.farnell.com/stmicroelec...dio-100w-ab-multiwatt15/dp/SC18436?st=tda7294
The 10 to 40 volt rating is a -/+ value signifying split rail operation. In other words -10 and +10 to -40 and +40 volt operation meaning a total 20 to 80 volts. Split rail designs have no speaker coupling capacitor.
If you measure 73 volts from ground then yours is most likely single rail operation.
Notice the way it is written as -/+ 40 volts (80 total across the chip)
It is always possible there is some other issue causing the chip to fail. We normally recommend use of a DBT (dim bulb tester) to prevent damage when testing amplifiers.
Date sheet:
TDA7294
You could try CPC in the UK, the illustrations are just, illustrations and do not show the difference.
https://cpc.farnell.com/stmicroelectronics/tda7294v/amp-audio-100v-100w/dp/SC08456?st=LDL104R/S
https://cpc.farnell.com/stmicroelec...dio-100w-ab-multiwatt15/dp/SC18436?st=tda7294
The 10 to 40 volt rating is a -/+ value signifying split rail operation. In other words -10 and +10 to -40 and +40 volt operation meaning a total 20 to 80 volts. Split rail designs have no speaker coupling capacitor.
If you measure 73 volts from ground then yours is most likely single rail operation.
Notice the way it is written as -/+ 40 volts (80 total across the chip)
It is always possible there is some other issue causing the chip to fail. We normally recommend use of a DBT (dim bulb tester) to prevent damage when testing amplifiers.
This is a known failure mode of TDA7293/7294. In my repair time I replaced several. Please replace for original parts not lottery won types.
Since I never found out WHY they exploded I googled a little and look what I found. Who would have thought that?
https://www.diyaudio.com/community/threads/solved-tda7293-blowing-up.408981/
There is a law in DIY audio that parts with faults, built in error modes, irregular sensitivities, imperfections or simply either unusually expensive or made of unobtainium are most popular 🙂
Since I never found out WHY they exploded I googled a little and look what I found. Who would have thought that?
https://www.diyaudio.com/community/threads/solved-tda7293-blowing-up.408981/
There is a law in DIY audio that parts with faults, built in error modes, irregular sensitivities, imperfections or simply either unusually expensive or made of unobtainium are most popular 🙂
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