Hi Guys
So I last posted on this same drive board asking for someone to confirm the transistors. I received the new ones today PZTA92 and installed them. I also checked the board and found "2D" transistor shorted. I replaced the 2D and PZTA transistor and them checked the board for any other shorts and solder bridges. Could not fine anything then I switched the amp on and found the a 240R resistor on the drive board burn up.
I removed the board inspected it again for any other faulty components but could not find anything. Replaced the 240R and switched the amp on and again it burnt the 240R.
In the pic the transistor in black was originally shorted and before replacing it I found the 2D in red. After switching the amp on the 240R burnt. This is the same resistor after replacing it burnt again.
Note there is no signal being put into the amp.
So I last posted on this same drive board asking for someone to confirm the transistors. I received the new ones today PZTA92 and installed them. I also checked the board and found "2D" transistor shorted. I replaced the 2D and PZTA transistor and them checked the board for any other shorts and solder bridges. Could not fine anything then I switched the amp on and found the a 240R resistor on the drive board burn up.
I removed the board inspected it again for any other faulty components but could not find anything. Replaced the 240R and switched the amp on and again it burnt the 240R.
In the pic the transistor in black was originally shorted and before replacing it I found the 2D in red. After switching the amp on the 240R burnt. This is the same resistor after replacing it burnt again.
Note there is no signal being put into the amp.
Attachments
Checked pin2 of driver board goes to a NPN transistor C2690 and that transistor goes to PNP A1220and output from there goes to 10r resistors feed output fets.
I do have the output fets out of the board.
I do have the output fets out of the board.
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No solder bridge. I used a digital microscope and checked the entire board for solder bridges. I also changed both the 072
Even though the transistor checks ok on a meter it could still be defective .
I’ve had that happen before were the transistor checks done but causes nothing but issues I replaced and no more issues
I’ve had that happen before were the transistor checks done but causes nothing but issues I replaced and no more issues
So today I changed the tl072 all the 1D and 2D transistors as well as the PZTA. Inspected board for solder bridges, put board back in and the 240R burns out.
If you pull the driverboard the amp should not be in protect. If it still protects id look at the a1220 and c2690 group of transistors or where that line goes too.
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with the driver board in with the buffer transistors amp does not go into protect but just burns the 240R . with the board out and the buffer transistors in the amp still does not go into protect. Amp powers up and I get my rail voltages regardless if the board is in or out.