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Recapped My Predicta Tandem, I don't know what to do
#22

Ok the good news is I found the reason for my white screen. The orange wire that goes on to the main board at CircuiTrace point 17 broke off. But stayed close to where it was supposed to be. I don't have a scope so I started checking voltages hoping to find something really off and found it. 

The bad news all my voltages are low. I followed the schematic from the switch to C1 the voltage is good leaving C1 145VDC exactly like the drawing. It looks like it goes through one diode and a micah cap then into the choke. The voltage should be 280VDC I have 240VDC. I checked the resistance on the choke it's dead on at 41ohms like the Sam's says. The voltage leaving the choke is 230VDC. At that point I checked the voltages at C2 100MFD it Should be 270 I have 229, 20MFd should be 250V I have 208V, C3 20MFD should be 115 I have 125. Also the 250VDC to the tuner is at 208VDC. Is it possible the (C50)  Micah cap is bad and it's bringing the voltage to the choke down? 

Also at the Picture tube Pin 7 should be 50VDC I have 30VDC, pin 4 should be 390VDC I have 334VDC. I also checked the junction of resistors 29 and 30 on the Amp board and got 230VDC instead of 270VDC I'm guessing its all caused by the low choke voltage?

What do you guys think?


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RE: Recapped My Predicta Tandem, I don't know what to do - by apERNA1985 - 01-06-2022, 11:35 PM



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