Cyber said:
I picked up an old heathkit O-11 at a garage sale for a few bucks. It
seems to work but makes a slight sizzling sound and after being on for
a few minutes emitts smoke. I think it is the caps in the power
supply. Does anybody know if these units can be rehabed?
Well, sort-of.
One, use your nose and eyes and see if you can locate the stinky part
(do not turn it on).
Usually the electrolytics need either forming or replacement; prolly
too late to try re-forming.
It is possible the problem is in the transformer, which is special -
it has a rather high voltage winding for the CRT, as i remember.
That winding has a tendency to break down, which results in what you
discovered (but ther may be other reasons for the smoke).
If the transformer is definitely the stinky part, then it is a very
good bet that HV winding is bad.
If you took the transformer laminations off, thenyou may get a better
look to find out if that winding is the outer-most one.
If so, then one could replace it, using better materials.
Count the turns per layer for the first 2 or 3 layers, and the number
of layers for the total turns.
You can use thin mylar tape for insulation in place wher paper was
used when you re-wind.
When the transformer in my O-1 when bad, i ordered a replacement
transformer from Heath (the O-1 was a kit still being sold then).
Be advised that this project would be useful only for re-habilitation
for working antique sales or other profitable purposes.
The O-1, while better than a number of the other inexpensive kits and
scopes at that time, you can get far better (used) scopes now for a cost
less than the time involved for restoration.