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Post by dummyload on Mar 17, 2016 6:19:50 GMT -5
That confirms the 0v on c25 , so the start up voltage is not present with j30 in place ,did you replace c25 recently ,check if pin 9 is not shorted (c25) to mains ground.
Check on pfc if sr1 ,ptc1,ptc2 are hot after about half minute on (j30 in place) ,disconnect mains wait until +9v led is out before you touch them.
So where is the squealing come from?
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Post by radiohead314 on Mar 17, 2016 6:21:10 GMT -5
17VM on primary side is also 0V
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Post by radiohead314 on Mar 17, 2016 6:27:01 GMT -5
That confirms the 0v on c25 , so the start up voltage is not present with j30 in place ,did you replace c25 recently ,check if pin 9 is not shorted (c25) to mains ground. Check on pfc if sr1 ,ptc1,ptc2 are hot after about half minute on (j30 in place) ,disconnect mains wait until +9v led is out before you touch them. So where is the squealing come from? With diode meter on pin 9 I measure 643mA one direction and OL in the other direction plus on pin 9. |
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Post by radiohead314 on Mar 17, 2016 6:46:17 GMT -5
Ok the squeling comes from the area where there are a lot of caps close. Not from the pfc and the resistor on the pfc is cold.
Hthd measures 0V
i put the old c25 back just to be sure but same measurements.
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Post by dummyload on Mar 17, 2016 6:49:35 GMT -5
That seems ok ,there should be 15v over Z50 if not check z50 and q60 for short and r52 and r53 if they are not open.
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Post by radiohead314 on Mar 17, 2016 6:51:19 GMT -5
Squeling might come from c25 very hard to determine
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Post by radiohead314 on Mar 17, 2016 7:06:44 GMT -5
That seems ok ,there should be 15v over Z50 if not check z50 and q60 for short and r52 and r53 if they are not open. 0V on Z50 z50 not shorted q60 not shorted r52 and r53 not open |
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Post by radiohead314 on Mar 17, 2016 7:16:18 GMT -5
Double checked no short from z90 to groun and no opel loop from top r52
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Post by dummyload on Mar 17, 2016 7:23:26 GMT -5
I would wait in changing the c25,first try to solve why there is no start up . (every time you replace components you degrade the pcb board do it as few as possible)
The voltage on Z50 is only shortly on and is cut by +17vm generated by I1 when the power supply comes a live and takes over from TH1 (but it's zero so no take over)
The squealing bothers me is there a short on one off the outputs from the fixed power supply preventing it from starting up ,one of the caps shorting the supply ,with no load the voltages are a lot higher then normal and that can make a cap fail but then again there should be a supply at c25 before the supply can start up.
Maybe reconnect d114 see if squealing changes , did it start after disconnecting d114?
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Post by dummyload on Mar 17, 2016 7:27:35 GMT -5
Sure you did not made a mistake in + pole and - pole of c25.
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Post by dummyload on Mar 17, 2016 7:38:34 GMT -5
From last measurements check diodes d50 and51 , and check for short between kathodes and mains ground to.
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Post by radiohead314 on Mar 17, 2016 7:50:55 GMT -5
Ok I made a mistake. Must be getting tired. For some reason I removed j30 and forgot to put it back.
I now measure 14,35V on the zener Z50.
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Post by dummyload on Mar 17, 2016 7:55:25 GMT -5
What do you have now on c25?
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Post by radiohead314 on Mar 17, 2016 7:59:33 GMT -5
I would wait in changing the c25,first try to solve why there is no start up . (every time you replace components you degrade the pcb board do it as few as possible) The voltage on Z50 is only shortly on and is cut by +17vm generated by I1 when the power supply comes a live and takes over from TH1 (but it's zero so no take over) The squealing bothers me is there a short on one off the outputs from the fixed power supply preventing it from starting up ,one of the caps shorting the supply ,with no load the voltages are a lot higher then normal and that can make a cap fail but then again there should be a supply at c25 before the supply can start up. Maybe reconnect d114 see if squealing changes , did it start after disconnecting d114? Ah ok I did not get that first. So in the end the I1 is making its own supply with the 17V. Cool. c25 is certainly connected right. I will check for a bad cap. |
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Post by radiohead314 on Mar 17, 2016 8:03:27 GMT -5
Sry wait a minute I check c25 and z50 again I am mixing thing up or do not know.
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