CT Sounds 7000.1
Working on a pair of these with the same problem; 1/2 blown PS, but the audio sides seem to be OK. Seems one of the amps will actually still power and play, but part of the PS smokes and obvious visible damage.
I have a chance to fine-tune the supplies in these if there are any slight circuit modifications to help with reliability. I had done something similar to a Lanzar 6k which was choking below 12.2vDC supply voltage - made that one run reliably down to about 9V by changing out the gate resistors to a lower value.
This amp is already running lower gate resistors then the Lanzar, and this amp has twice the PS driver transistors.
-PS Fets are IRFP1405 which there are 24 total in each amp - I have a sleeve now on order to replace.
-Drivers were KTC2814/KTA1715 and mostly blown, which I plan on replacing with MJE182G/172G. Amp has 8 driver transistors
-470ohm resistors before the above drivers connecting back with 200 and 400 ohm resistors to the PS driver board.
-PS Gate resistors are 22 ohms. Many are out of spec and so I'll be replacing all of them
-3.3k pulldown resistors
With no PS fets, this setup gives a perfectly clean square drive from 8v to 16v supply
Anything here need any tweaking by chance?
Working on a pair of these with the same problem; 1/2 blown PS, but the audio sides seem to be OK. Seems one of the amps will actually still power and play, but part of the PS smokes and obvious visible damage.
I have a chance to fine-tune the supplies in these if there are any slight circuit modifications to help with reliability. I had done something similar to a Lanzar 6k which was choking below 12.2vDC supply voltage - made that one run reliably down to about 9V by changing out the gate resistors to a lower value.
This amp is already running lower gate resistors then the Lanzar, and this amp has twice the PS driver transistors.
-PS Fets are IRFP1405 which there are 24 total in each amp - I have a sleeve now on order to replace.
-Drivers were KTC2814/KTA1715 and mostly blown, which I plan on replacing with MJE182G/172G. Amp has 8 driver transistors
-470ohm resistors before the above drivers connecting back with 200 and 400 ohm resistors to the PS driver board.
-PS Gate resistors are 22 ohms. Many are out of spec and so I'll be replacing all of them
-3.3k pulldown resistors
With no PS fets, this setup gives a perfectly clean square drive from 8v to 16v supply
Anything here need any tweaking by chance?
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Put all the PS Fets in, new drivers, and gate resistors. Amp powers and produces Rail voltage. Draw from my bench seems a bit higher than I would have liked to see; 5A at 10vDC and 7.5A at 16vDC. Right at 6.5 at 14.4vDC. Signal on gate looks to be alright. Nothing is heating up.
Any room for improvement?
Photo of gate drive signal:
Any room for improvement?
Photo of gate drive signal:
Attachments
Found a stability problem with one of these amps; which would have caused a 1/2 blown PS. Both amps ended up having this problem as well. Im not sure if this is on the CD in one of the Generic Class D folders, but important to mention specifically for these amps. While these amps suffer from vibration damage; if the PS FETs and drivers fail, its worth it to check the PS driver board near the 220ohm resistors. In both of my amps, the traces show signs of overheat and were intermittently causing drive signal to fail. Essentially there are 2~3 pads and 2 legs of the driver board needing to be CHECKED and Built up after replacing the TL494. Vibration and bad connections would have almost immediately caused both of these amps to fail again.
Attachments
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Specifically, the trace between E2 pin 10 and the driver board's last leg was discolored and had a poor connection. Its a straight trace from E2 to the last leg, connected also to a 220R, but I was having trouble continuity checking. After rebuild, touching and flexing the driver board caused degraded signal to half the drivers/fets. E1 was OK but I enhanced anyway.
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