Rebuilding a Hoffman 610

[Eric H]

Originally Posted by jeyurkon

It's starting to look pretty good. You said you only got a little HV when you started. Is it normal now that you replaced the bad electrolytics?

John

My HV probe seems to be inaccurate but based on how the set works now I'd say it's up to spec.

I had a faint bright drive line on the right side of the screen that wouldn't adjust out so I went through and checked a bunch of resistors in the sweep circuits.

I found an 82 ohm coming off the Horiz Frequency coil that had gone up in value to about 145 ohms, replaced that and the drive line in gone, it's also very stable at this point.

Replaced a couple other drifted resistors and this set has a really good picture now.

There is one 200Mf @ 6v cap to replace, I'll pick one up tomorrow at the local Electronics store and finish it up.

The controls still need to be cleaned and lubed.

The chassis was covered in a white powdery dust, I'm sure we've all seen this, it's more often yellow but this one was white.

I'm treating it like it's Cadmium Oxide, i.e. being very careful, I vacuumed as much as I could with a Hepa Filter in the Vac, the rest I'm cleaning off with a very diluted solution of Naval Jelly and water, this is about the only thing I've found that gets it off well, cleans it down to bare metal I think or at least down to whatever plating is left.

It's slow going, doing a small area at a time so I don't get Acid in anything important like the i.f coils.