I was curious about the Multiplier, how much is it and what's inside it and why can't they be rebuilt? Nice video TG, look fwd to seeing what's next. Best Wishes & Blessings. Keith Noneya
The multiplier is made up of g HV diodes/capacitors/resistor. The diodes is typically what shorts and fails and shorts the HV secondary winding on the HV transformer out. Unfortunately they are potted and sealed assembly, so trying to rebuild one will likely result in destroying the module. Now the CRT on these don’t need the 14 kV PDA (post deflection acceleration) to produce a display. Without the PDA, the image will have lower, intensity, poor focus, and the wrong deflection, trick I learned many years ago when testing them is to remove ground strap to remove short and 50k oscillator sure start, if not you can feed 50k frequency to pin 1 and 14 on neck of CRT push voltage to 10v peak to peak, or as high as signal generator will allow to test HV supply and sure get a few hundred volts enough to get a image to see if HV transformer is good and not shorted. I could build a multiplier but would have to see if it fits and pot it is the problem. One of the odd designs Tektronix did was put -2.4kv across filament for noise rejection and etc. The heater is tied to the cathode which is at -2450V. Typically most CRT’s are 6.3V. Another safer way to check is If the HV multiplier is shorted, it will also load down transistor Q1404. Check the voltages on it, they should be, if not the multiplier likely at fault. Voltages on Q1404 sure be Collector: +4.4V Base: +0.7V Emitter: +0.1V
I was curious about the Multiplier, how much is it and what's inside it and why can't they be rebuilt? Nice video TG, look fwd to seeing what's next. Best Wishes & Blessings. Keith Noneya
The multiplier is made up of g HV diodes/capacitors/resistor. The diodes is typically what shorts and fails and shorts the HV secondary winding on the HV transformer out. Unfortunately they are potted and sealed assembly, so trying to rebuild one will likely result in destroying the module.
Now the CRT on these don’t need the 14 kV PDA (post deflection acceleration) to produce a display. Without the PDA, the image will have lower, intensity, poor focus, and the wrong deflection, trick I learned many years ago when testing them is to remove ground strap to remove short and 50k oscillator sure start, if not you can feed 50k frequency to pin 1 and 14 on neck of CRT push voltage to 10v peak to peak, or as high as signal generator will allow to test HV supply and sure get a few hundred volts enough to get a image to see if HV transformer is good and not shorted.
I could build a multiplier but would have to see if it fits and pot it is the problem. One of the odd designs Tektronix did was put -2.4kv across filament for noise rejection and etc. The heater is tied to the cathode which is at -2450V. Typically most CRT’s are 6.3V.
Another safer way to check is If the HV multiplier is shorted, it will also load down transistor Q1404. Check the voltages on it, they should be, if not the multiplier likely at fault. Voltages on Q1404 sure be
Collector: +4.4V
Base: +0.7V
Emitter: +0.1V