Well that narrows down things a bit. Just to be clear, you have pulsating protection with and without the Rectifiers BR1 and BR2 correct?
I would focus on the input filters inductor L1-5uH.CP35-220uF, CP33,34-2200uF, CP31,32,CP7,8-104c.
It appears from the pics the inductor is rubbing against the positive power terminal, although the angle makes it difficult to read.
I would focus on the input filters inductor L1-5uH.CP35-220uF, CP33,34-2200uF, CP31,32,CP7,8-104c.
It appears from the pics the inductor is rubbing against the positive power terminal, although the angle makes it difficult to read.
The current post contradicts your post #18
"OK so without the rectifiers and no outputs in the circuit. The amplifier does the same strange pulsating."
If the current post is correct, that would make more sense. You may have two separate problems. The pulsating protection is most likely caused by one or more shorted transistors in the output, or a broken/ bad connection or open resistors in the fixed biasing for the outputs.
Yes it's power supply without the rectifiers is running. With the rectifiers the pulsating protection. I have pulled and checked so many transistors ect...
The problem has to be after the rectifiers, maybe regulated power supply , input on main board or daughter board or Output Stages.
Check the regulated power supply-Q23 and Q30 and associated circuit. There may be a short across on or both (+/- 15 volt) of the regulated supply, possibly caused by one of the Input IC's (2068's or 4558's) or the 100uF 25v (CP1 or CP11).
If and when you get the the output stages, be sure that you have lifted all eight of the 10K ohm resistors. (4 are tied to output protection and 4 are tied to DC protection). Also, DP7 can be lifted to disable DC protection.
Check the regulated power supply-Q23 and Q30 and associated circuit. There may be a short across on or both (+/- 15 volt) of the regulated supply, possibly caused by one of the Input IC's (2068's or 4558's) or the 100uF 25v (CP1 or CP11).
If and when you get the the output stages, be sure that you have lifted all eight of the 10K ohm resistors. (4 are tied to output protection and 4 are tied to DC protection). Also, DP7 can be lifted to disable DC protection.
I have pulled every transistor and tested them all. Pulled all 8 10kohm protection resistors, and dp7 and well. Protection persists still.
Check the regulated +/-15 volt supply. Q23-2SD882,Q30-2SB772,ZD6,7-16v zener, CP21,29-100uF/25v.
I have checked all stated and all transistors in the channel s have been pulled and tested.
All with blue paint are good and checked.
Values of
Q404
Q204
Q304
Q104
One of these are incorrectly placed.
3 mpsa06
1 mpsa56
All with blue paint are good and checked.
Values of
Q404
Q204
Q304
Q104
One of these are incorrectly placed.
3 mpsa06
1 mpsa56
Attachments
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Sorry about that I notice that 3 of the 4 transistors were mpsa06 and only one of the four was a mpsa56. So I was wondering were q104-q404 all mpsa06, or is it a 50/50?
This Amp was previously attempted repair. So I need the verify the outputs are even correct. I have
Q209 B668
Q204. Mpsa56
Q203 D718
Q409. B668
Q404 MPSA06
Q403 D718
Q209 B668
Q204. Mpsa56
Q203 D718
Q409. B668
Q404 MPSA06
Q403 D718
Here is the breakdown for the output stages:X=100,200,300,400 series
QX02,QX05,QX06-MPSA56-Diff amp
QX10-MPSA56-driver for the QX09-B688
QX01-MPSA06-driver for the QX03-D718
QX04-MPSA06-Bias transistor
QX12-MPSA06-predriver transistor
Q204 should be MPSA06
You may want to replace all Outputs and transistors in Amp 2.
QX02,QX05,QX06-MPSA56-Diff amp
QX10-MPSA56-driver for the QX09-B688
QX01-MPSA06-driver for the QX03-D718
QX04-MPSA06-Bias transistor
QX12-MPSA06-predriver transistor
Q204 should be MPSA06
You may want to replace all Outputs and transistors in Amp 2.
Still just pulsating. Changed entire channel, testing for voltage at the backs of the rectifiers they have - 1.51vdc. From main ground. Tested each channel. All have the exact resistence all the transistors and or mosfets as well.