A while back I picked up a Tektronix 575 Mod 122C transistor curve tracer from Craigslist and just started digging into it. With some encouragement from reader petepdx, I’ve started actually looking into fixing it up. (Click the photos for a much larger view!)
Inside, there’s some pitting and build-up, and some mildew visible around the CRT socket. There’s also a good bit of detritus floating around, from what looks like an insulator or spacer near the base of the CRT which disintegrated.
Nearly every tube was cracked in the socket. This must have taken a heck of a beating at some point. Dropped, maybe?
Using a shop-vac with a miniature brush, most of the dust and grime and bits of gasket cleaned right up. It’s actually not in as bad of a condition as it seems initially, at least cosmetically.
This doesn’t look great, though:
I do have a spare CRT for this unit, which seems to be in good shape. I haven’t pulled this CRT to see if it’s damaged.
There was a bit of dust, and white whispy build-up which could have been mildew on the paper insulation of most of the transformers.
Lots of surface corrosion in random places, too.
The inside of the Collector Sweep power supply doesn’t look too bad, though…but there’s that white discoloration on the main collector sweep power transformer still. Up top, not too bad. petepdx noted there should be a spool of silver solder inside – which there is!
It is desirable that only silver bearing solder be used on the ceramic terminals and for tinning the iron. Ordinary tin-lead solder may be used but repeated use will break the solder-to-ceramic bond. See your instruction manual.
Big power supplies on the bottom.
Lots of surface rust on one side of the main power transformer. On the panel-mount rectifier diodes, too.
Up top, there’s the horizontal and vertical drive circuits and the step generator circuits.
Finally, underneath is the CRT anode power supply, among other things. Some more white build-up here.
I also have a handful of the front panel switches, a full set of good pulled tubes, and a CRT from a 575 standard variant if I need them for spares. Overall, this is a bit of an oddball. There’s the mildew on the transformers, some mildew around the CRT, some evidence of water damage in the corners…the fuse holder is missing its cap, and was full of mud, and there’s some corrosion on the bottom deck neon bulbs. Otherwise, though, it’s actually surprisingly clean.
I’ll be going through it with a damp cloth shortly to remove even more grime and dust, and will post some photos of that step, then start looking into component replacements.
Possible plan for the resto:
- Thorough cleaning of grime and dust, oil fan bearings, clean/replace filter.
- Check and replace carbon comp resistors as needed.
- Replace tubular capacitors. Counted 18, may be some more hiding in there somewhere.
- Replace neon bulbs which appear in several circuit locations.
- Evaluate and replace as needed panel mount and ceramic terminal strip silicon diodes.
- Evaluate replacing HV power supply rectifier tubes with silicon diodes.
- Replace electrolytic capacitors. Quite a few of those.
- Visually inspect CRT.
- Test and replace tubes.
- Power it up with a Variac and hope nothing catches on fire.
It’ll be a big job to give it a full overhaul, hopefully nothing is too badly damaged which would make it impossible…