I was recently given a very tired Tektronix 465B oscilloscope that was in need of some TLC. It basically worked in that there was a trace on the screen that could be controlled by the usual ‘shift’ controls, but there was some ‘Z’ modulation on the trace and some fold-over or re-trace problems. There was also several years of accumulated dirt that would need to be removed, but that was minor.
A check on the voltage rails showed something was not right with the unregulated 110 volt line and this was traced to the two smoothing capacitors C4439 and C4429 which I now understand are known for causing problems.
Much to my surprise, after I replaced the two capacitors and adjusted the 55volt rail (which is used as the reference for the other rails) the oscilloscope worked very well with no sign of the previously noted faults, even the calibration did not need adjusting.
On advice from a friend I changed the two bridge rectifiers (which are apparently slightly under-rated,) and a tantalum electrolytic (C4006 47μ 35V) that decouples the supply to the E.H.T. generator.
Now turning to the aesthetics, the front panel and controls were cleaned with warm water with just a touch of soap, and applied using an old toothbrush and plenty of kitchen paper towel , taking care not to get the front too wet. The handle and rear plastic fixing was cleaned with carpet cleaning moose and with a little help from the toothbrush, the dirt just fell away. The metal case was in a bad way with lots of scraps, scratches and a few dents. I decided a full strip and re-spray would be the best way forward. A trawl through the forum resulted in a post from Craig Sawyers in which he mentions a company called Paints4U who were able to supply paint matched from a sample previously supplied by Craig. I contacted Paints4U who, after some digging into their archives, found the formula and supplied a spray can of ‘Tektronix Blue’ Paint.
To remove the old paint, the case was treated with a proprietary paint stripper, cleaned, de-greased and then sprayed witha coat of acid-etch white primer. The following day I sprayed the case with the ‘Tektronix blue’ (two coats) then left the case in a warm place to dry before re-assembly. My Son kindly 3D ’printed’ a set of rear feet which finished the job nicely.
In general, I am very pleased with the result. I think the scope has been dropped at some time in its history as the front casting is slightly bent, but it doesn’t affect the operation of the scope so I can live with that.
If anyone would like to ‘freshen up’ their Tektronix equipment, Paints4U can supply the paint in spray cans which can be ordered on-line (mine came the next day). If a contact there is needed, Josh knows all about it.
https://www.paints4u.com/
Dave