all of the output transistors checked good in diode check mode . i pulled them from the board and powered the amp up and it still blew the 15a fuse.the gate resistors all read 47 ohms,the positive rectifier are reading 353 from the middle leg to the outside the,the negative rectifier starts out low and climbs until its reads like the meter leads are touching nothing still in the diode check mode.the fets are reading 156 from the chassis ground to the gate on all 8 fets.
i rechecked the rectifiers the 32r with the leads BRB 345 with the leads RBR climbs until it reads OL.the 32s with leads BRB climbs until it reads OLwith the leads RBR 345,while still in the board.the outputs are reading a1962 RBB 0,BRR 530,BR 0,RB 0.the c5242 RBB 540,BRR 0,BR 0,RB 0.while out of the board.
If you have transistors that read 0 ohms across their leads when out of the board, they are defective.
The rectifiers appear to be OK.
Is there a low value resistor connected from the gate drive to chassis ground (generally a 220 ohm near the gate resistors)? If so, that could be causing the .156v reading.
The rectifiers appear to be OK.
Is there a low value resistor connected from the gate drive to chassis ground (generally a 220 ohm near the gate resistors)? If so, that could be causing the .156v reading.
i should of put a ol instead of 0 for the transistors sorry.what are the parts k d600k y 350 and k b631k y 343.the 631 is reading RBB OL,BRR 638,BR OL,RB 637.the 600 is reading RBB 585,BRR ol 583 (this one in reading funny if i touch the first one and the second one it reads OL,the first one to the last one it reads 583),BR 586,RB OL.so maybe the 631 is bad?
It's a bit confusing if you don't tell us whether you're using the meter set to ohms or diode check. If you switched from diode check to ohms when you read 157, then you were simply reading the 110 ohm and the 47 ohm resistors in series. The 110 ohm resistors are pull-down resistors and will keep the power supply transistors turned off if the PNP driver transistor is removed or fails-open. A value as low as 110 ohms also helps the PNP transistor to more quickly turn the transistors off.
If you have more transistors to check (out of the board), use the link at the bottom of the 'Checking Bipolar Transistors' section on the following page. The link is just above 'Counterfeit Semiconductors'.
http://www.bcae1.com/repairbasicsforbcae1/repairbasics.htm#checkBJTs
If you don't want to post a screen cap, simply let us know that you're using that form and indicate the lead placement (numbers 1-6) and the meter reading.
If you have more transistors to check (out of the board), use the link at the bottom of the 'Checking Bipolar Transistors' section on the following page. The link is just above 'Counterfeit Semiconductors'.
http://www.bcae1.com/repairbasicsforbcae1/repairbasics.htm#checkBJTs
If you don't want to post a screen cap, simply let us know that you're using that form and indicate the lead placement (numbers 1-6) and the meter reading.
With your meter set to DC volts...
Touch one lead to the center leg of the output transistors and the other lead to the secondary center-tap of the transformer (or to the RCA shield or to the negative speaker terminal - all of these should be directly connected).
You should read approximately positive 50v on half of the output transistors and approximately negative 50v on the other half of the output transistors.
I'm guessing that the rail voltage is ±50v. It could be as low as ±35 or greater than ±60.
Touch one lead to the center leg of the output transistors and the other lead to the secondary center-tap of the transformer (or to the RCA shield or to the negative speaker terminal - all of these should be directly connected).
You should read approximately positive 50v on half of the output transistors and approximately negative 50v on the other half of the output transistors.
I'm guessing that the rail voltage is ±50v. It could be as low as ±35 or greater than ±60.
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