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.

[Eric H]

Originally Posted by jeyurkon

That's a nice looking set. Is the stand a matching item for the TV?

John

John, I found the answer to this question and it's yes!
It might be a better fit for the 12" set though.
It also says the 610 has a receptacle for a Phonograph but mine doesn't.
From tvhistory.tv:

[jeyurkon]

That chassis is looking pretty good! Your experience with the white line will be helpful to the rest of us also.

On my Sylvania I'm supposed to adjust the horizontal linearity until one shows up in the center and then back off. I used to get this before I finished fixing some other problems, but now I can't get the white line back. They say to leave the pot. at max in that event. I feel nervous doing that. I still backed it off some.

I have several HV probes. Though they all seem to be calibrated properly, two of them draw a lot more current than the other. Those two read lower when I use them because they cause a big drop across the resistor that's in series with the HV CRT connector. They do seem to read correctly on sets that have lower impedance HV supplies. Sounds like you're having the same experience.

John

[jeyurkon]

Cool! That's a great find getting the original stand!

Jon

[Eric H]

Got it back in the cabinet. (the last cap can be changed from the bottom)
It always makes big difference watching it in the cabinet, especially with a thick piece of Yellow/Green glass in between you and the CRT.

I tried to capture the color as best as my camera would allow, the second and third pictures are probably the closest to accurate.


The safety glass is seriously thick on these, about 1/2" total, 3/8" of Yellowish glass laminated to a piece of clear 1/8" glass, perhaps the rumor that Hoffman got a deal on some surplus window glass from a high rise was true? Though why anyone would want that color in their office building I can't fathom.

[Charlie]

that's awesome looking, Eric! Aunt Bea never looked so good!

[jr_tech]

IMPRESSIVE!
Very nice to see it running so well! Gives me some hope for mine.
So all of the orig. paper caps were replaced?
jr

[bandersen]

Nice job

Originally Posted by Eric H

...Though why anyone would want that color in their office building I can't fathom.

Maybe to block UV or glare ?

I've been using Naval Jelly lately too for cleaning up metal surfaces. Works pretty good I think, but like you said, be careful with that acid!

[peverett]

I have restored some later model(1953-1954) Hoffmans. The green glass is thinner, but still laminated with plastic and true safety glass.

I like what the ad above implies when it says "Easy Vision Television Price of Ordinary". It means-green glass at no extra cost!

[Dan Starnes]

Aunt Bea never looked so good!

[Eric H]

Thanks guys, this set was a pretty straightforward restore, it worked somewhat when I got it so I knew everything was more or less OK and it just needed caps.

Jr, yes, all the paper and electrolytics have been replaced, except one small lytic that I will replace as soon as I get a new one, also the line filter caps are still original, I have the X type (or maybe it's Y) safety caps to replace them with but just haven't done it yet.