Tektronix 465M repair

[andy3055]

I have some new info in that, I have created the final configurations of the HV/EHT sections.

1. The Partial HV block shows the high voltage section of the U550 HV module. Space has been left (at the bottom of the picture) to accommodate the EHT section.

2. The EHT section shows the final physical configuration of the EHT section.

3. Test setup was done to make sure there is adequate spacing between components in the EHT section.

All that remains is to do the final potting. Hopefully that goes well.

[andy3055]

Potted the EHT section and tested. All seems to be OK so far. Nothing smoked or shorted etc. Will tweak the voltages and update. There is not a lot I can do without other equipment for a full calibration per the manual.

[andy3055]

32 volt supply adjusted. CRT bias adjusted. At this point I called it "done" as I do not have equipment to do the rest of the adjustments. In any case, it will be good enough for my kind of work.

I wish to thank all who contributed with many ideas, tech info etc. to make this a success and I hope someone else can take some pointers from this thread.

[jdragoset]

 
Great Job!

[andy3055]

 Thanks.

[kenchill1]

I used an NTE-538 tripler to replace the shorted High voltage multiplier. The scope was blowing the 32v fuse. All I did was unsolder the pin 10  (closet above board pin the the edge) of the horizontal transformer and solder a wire to the IN of the NTE538 and splice and solder High voltage lead to the HV elbow connector. No other tripler connections are used. i snipped off the high voltage wire and unused wires on the 538. 12kv is present. i did not remove the old HV multiplier and left everything else alone. i sealed the splice with silicone rubber and glued the 538 to the old HV multiplier. Works fine with a bright sharp trace. see photo.

[andy3055]

Well, since that time, the scope failed again. This time it had a fault in the timebase module that permanently damaged the main board. Ended up getting a main board and a timebase module from the Tek museum folks in Beaverton. So far no problems after that.

[andy3055]

A member has asked me questions about this repair and to the benefit of him and any others, I am updating the thread with some info. My repair was successful, but as noted in earlier comments the scope failed due to the time base module becoming faulty that created havoc in the MB. I had no time nor the energy to go at this again and ended up replacing them that was found for me by a kind soul at the Old Tek Museum. Thanks to him, the scope is still working today. 

Disclaimer to the person(s) intending to use this info:

Please note that you are dealing with extra high voltages in the range of 3-10 kV or more. Therefore you are doing this at your own risk. EEVBlog nor I take any responsibility for any damage or harm to your equipment or to yourself. If you are a novice, please get help from someone who is experienced.

The EHT section was built with Caps at 6 kV and diodes at 20 kV. Other diodes are at 4 kV and the caps at 3kV although theses caps should be at a higher rating. With the space available, it is hard to find better components.

The 465M has all these components in one block - U550. My idea was to build it in a way that it is easier to replace with new parts without building a whole new unit.

[andy3055]

More pictures

[andy3055]

Last one!