Bert Kuijpers
New Member
During my move from East London to Mosselbay (RSA) my S51B Telequipment scope packed up. I am going banana’s for weeks now. I have a circuit diagram downloaded. Not all the voltages correspond with the diagram.
The fault: no sweep. When I remove the ECF80, I get a dot just over my middle line, I am able to measure incoming signal and have been able to measure and repair a few PC boards in this way. But it is cumbersome.
The focus does not work, but my Brightness, X gain, X shift seem to work. The Time/CM + Variable in all positions does not work (because no sweep).
I am now decoding all the various positions of the Time/cm switch to see what makes the voltage sweep from 140 Volt pin 7 (CRT) to 316 Volt pin 8.(CRT) If I pull the ECF80 out, both pins have approx the same voltage and therefore I have a spot on the screen.
After hours I discovered that R 50 (330K) was never in the scope and have to start all over again.
Who can help me. How does the sweep start? How does it works? I get 6 Volt on the anode of tube V5a which should be 50 Volt. I get 3 Volt DC on intersection R 73/R 80/ Rv72 which also seem to me not right. The switch settings merely makes the sweep faster or slower. I have therefore to look for something common.
Some info: R 62 is overheating Ra – V6b = 120V instead of 350 Volt
R 63 drops to 22 Volt. Anode V5a drops to 11 Volt instead of 50Volt
Testpin 56 = 1 Volt testpin 48 = 120 Volt R 58 = 16 Volt
What systematic method can I apply to find the fault.
The fault: no sweep. When I remove the ECF80, I get a dot just over my middle line, I am able to measure incoming signal and have been able to measure and repair a few PC boards in this way. But it is cumbersome.
The focus does not work, but my Brightness, X gain, X shift seem to work. The Time/CM + Variable in all positions does not work (because no sweep).
I am now decoding all the various positions of the Time/cm switch to see what makes the voltage sweep from 140 Volt pin 7 (CRT) to 316 Volt pin 8.(CRT) If I pull the ECF80 out, both pins have approx the same voltage and therefore I have a spot on the screen.
After hours I discovered that R 50 (330K) was never in the scope and have to start all over again.
Who can help me. How does the sweep start? How does it works? I get 6 Volt on the anode of tube V5a which should be 50 Volt. I get 3 Volt DC on intersection R 73/R 80/ Rv72 which also seem to me not right. The switch settings merely makes the sweep faster or slower. I have therefore to look for something common.
Some info: R 62 is overheating Ra – V6b = 120V instead of 350 Volt
R 63 drops to 22 Volt. Anode V5a drops to 11 Volt instead of 50Volt
Testpin 56 = 1 Volt testpin 48 = 120 Volt R 58 = 16 Volt
What systematic method can I apply to find the fault.
