thunter0512
Veteran Member
Last Sunday I picked up a very dirty and corroded Tektronix 4010. I spent two days on disassembly and cleaning and now I am looking for advice on getting the terminal going again.
Roland Huisman had some of the same issues as documented in this 3 year old thread: https://forum.vcfed.org/index.php?threads/tektronix-4010.77121/
I have removed the power supply from the pedestal and identified it as a "Heavy Duty (HD) Power Supply" used if you have some of the optional extras which require more power.
Roland's Tek 4010 had a so called "Low Voltage (LV) Power Supply).
I would like to reform the 4 large electrolytic filter caps (C33 dual 150 uF, C5 and C205 9600 uF, C255 86 mF - (yes milli-Farad)) in my supply before attempting to power on the supply for stand alone load testing.
Unlike other power supplies I worked on it seems very tricky to isolate the soldered in capacitors (C33, C5 and C205) to allow for individual slow re-forming via a current-limited bench supply.
It appears that I have to completely disassemble the power supply to be able to desolder the 3 caps (C255 has screw connectors but the PCB still has to be removed to get C255 out). Roland too complained about the "worthless construction".
It seems I have to remove the rear hit sink to access the bolts holding 3 of the filter caps, unsolder at least some of the transformer's heavy duty secondary leads, disconnect a few connectors going to the heatsink, remove the supply PCB, and possibly more I haven't discovered yet before I can even think about removing the filter caps. This is surprisingly complex to just isolate or remove the filter caps.
I don't believe in variac based "reforming" but wonder if this is my only viable option.
In my experience reforming of individual caps via a current limited bench supply works well, limiting current to a say 10 mA and slowly increasing the voltage from 1V to the rated voltage pausing after each increase until the current drops to zero or close to zero.
Of course this only works if you can isolate at least one pin of the capacitor, otherwise something else in the circuit will draw current.
I think it would be irresponsible to just apply mains power to the power supply and risk blowing up the very large and expensive (unobtainium?) electrolytic caps.
Another problem is that the Tek 4010 maintenance manual on Bitsavers has no parts list for my "Heavy Duty (HD) Power Supply" (see https://bitsavers.org/pdf/tektronix/401x/070-1183-01_Rev_B_4010_Maintenance_Manual_Apr_1976.pdf).
Any thoughts or advice or suggestions?
Roland Huisman had some of the same issues as documented in this 3 year old thread: https://forum.vcfed.org/index.php?threads/tektronix-4010.77121/
I have removed the power supply from the pedestal and identified it as a "Heavy Duty (HD) Power Supply" used if you have some of the optional extras which require more power.
Roland's Tek 4010 had a so called "Low Voltage (LV) Power Supply).
I would like to reform the 4 large electrolytic filter caps (C33 dual 150 uF, C5 and C205 9600 uF, C255 86 mF - (yes milli-Farad)) in my supply before attempting to power on the supply for stand alone load testing.
Unlike other power supplies I worked on it seems very tricky to isolate the soldered in capacitors (C33, C5 and C205) to allow for individual slow re-forming via a current-limited bench supply.
It appears that I have to completely disassemble the power supply to be able to desolder the 3 caps (C255 has screw connectors but the PCB still has to be removed to get C255 out). Roland too complained about the "worthless construction".
It seems I have to remove the rear hit sink to access the bolts holding 3 of the filter caps, unsolder at least some of the transformer's heavy duty secondary leads, disconnect a few connectors going to the heatsink, remove the supply PCB, and possibly more I haven't discovered yet before I can even think about removing the filter caps. This is surprisingly complex to just isolate or remove the filter caps.
I don't believe in variac based "reforming" but wonder if this is my only viable option.
In my experience reforming of individual caps via a current limited bench supply works well, limiting current to a say 10 mA and slowly increasing the voltage from 1V to the rated voltage pausing after each increase until the current drops to zero or close to zero.
Of course this only works if you can isolate at least one pin of the capacitor, otherwise something else in the circuit will draw current.
I think it would be irresponsible to just apply mains power to the power supply and risk blowing up the very large and expensive (unobtainium?) electrolytic caps.
Another problem is that the Tek 4010 maintenance manual on Bitsavers has no parts list for my "Heavy Duty (HD) Power Supply" (see https://bitsavers.org/pdf/tektronix/401x/070-1183-01_Rev_B_4010_Maintenance_Manual_Apr_1976.pdf).
Any thoughts or advice or suggestions?
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