wrote in message
ups.com...

I did a very stoopid thing.

I hollowed out a capacitor and epoxy in a new snap in capacitor inside
the old can. I didn't use the proper voltage rating capacitor and now
I have to un-epoxy. Any ideas?

I already called myself stoopid so no need to duplicate efforts there.


Solvent?

Heat?

Dremel?

thanks
N9NEO

Acetone will soften some epoxies. So will heat...smoking hot heat.
It would probably be better to drill out the old capacitor, or just
call it a learning lesson, and get a NOS cap from Surplus Sales of
Nebraska, or Antique Electronic Supply (AES). Between the two of them,
you can get just about any old cap ever made.

Also, why epoxy? It isn't like the capacitor needs to be really strong.
Use hot glue next time. Always think reversible.

-Chuck

Chuck,

I was replacing the steel ring on the top with the tabs. The tabs are
what gets soldered into the steel chassis.

I am a little bit nervous about buying nos caps. And prices for some
of those damn multi-section caps are up in the twenty-thirty dollar
price range. Besides I get a very good deal on the little snap-in
capacitors that I plunk inside.

regards,
Bob

Chuck Harris wrote:
wrote in message
ups.com...

I did a very stoopid thing.

I hollowed out a capacitor and epoxy in a new snap in capacitor inside
the old can. I didn't use the proper voltage rating capacitor and now
I have to un-epoxy. Any ideas?

I already called myself stoopid so no need to duplicate efforts there.


Solvent?

Heat?

Dremel?

thanks
N9NEO

Acetone will soften some epoxies. So will heat...smoking hot heat.
It would probably be better to drill out the old capacitor, or just
call it a learning lesson, and get a NOS cap from Surplus Sales of
Nebraska, or Antique Electronic Supply (AES). Between the two of them,
you can get just about any old cap ever made.

Also, why epoxy? It isn't like the capacitor needs to be really strong.
Use hot glue next time. Always think reversible.

-Chuck

Hi Bob,

There really isn't any reason to be nervous about NOS electrolytics,
they are either reformable, or dried out. The shelf life on *any*
electrolytic is only about 2 years, so you should reform any electrolytic
that has been stored longer than that.

If all the epoxy is doing, on this rebuild, is holding the can to
that ring, your dremel tool should do an adequate job of carving
away the excess epoxy.


Good deal or not, your little snap in capacitors didn't do the trick
this time, and you get to do the job again. I hate it when that
happens, but sometimes it does.


-Chuck

wrote:
Chuck,

I was replacing the steel ring on the top with the tabs. The tabs are
what gets soldered into the steel chassis.

I am a little bit nervous about buying nos caps. And prices for some
of those damn multi-section caps are up in the twenty-thirty dollar
price range. Besides I get a very good deal on the little snap-in
capacitors that I plunk inside.

regards,
Bob

Yea Chuck,

What I did was to regard a penciled in voltage on a schematic as real.
Previous owner penciled in 600v on the plate supply. So ok I figured
I'd stick a 450v cap in each of the two hollowed out cans and I'm good
for near 900v with a pair of sharing resistors. About the time I get
the caps all epoxyed in I take a look at the new Peter Dahl plate
transformer schematic and it says 700v on the plate windings. Sure
enough 700vrms is about 1kv, so my two free 450v caps aint gonna hack
it. I got some free 30mmx30mm 220uf 400v cans. I'll get two of em
into each can this weekend and I'll be ok.

Into the transmitter for about 500 bucks now and it's worth about 200
working. Needless to say I don't want to burn out the new transformer
with a botched recap job.

73
Bob

wrote:
Yea Chuck,

What I did was to regard a penciled in voltage on a schematic as real.
Previous owner penciled in 600v on the plate supply. So ok I figured
I'd stick a 450v cap in each of the two hollowed out cans and I'm good
for near 900v with a pair of sharing resistors. About the time I get
the caps all epoxyed in I take a look at the new Peter Dahl plate
transformer schematic and it says 700v on the plate windings. Sure
enough 700vrms is about 1kv, so my two free 450v caps aint gonna hack
it. I got some free 30mmx30mm 220uf 400v cans. I'll get two of em
into each can this weekend and I'll be ok.

Into the transmitter for about 500 bucks now and it's worth about 200
working. Needless to say I don't want to burn out the new transformer
with a botched recap job.

73
Bob

Hi Bob,

That hurts!

The two series connected 450WV caps would be ok with a no load voltage of
980V. It was a pretty common practice to let things like that happen back
in the day. The capacitors will respond to the excess voltage by building
a little more oxide layer... assuming that they are in good shape to begin
with.

But you will be safer going to the higher rated caps. If you are going
to stick two 400V caps in the same can, be warned that the plastic sleeve
on the 400V caps isn't good for 400V. Use some better insulation. I got
a serious arm-to-arm shock trusting some capacitor insulation when I
foolishly clamped a cap to a floating chassis. I learned a couple of
important lessons that day!

-Chuck

Yea, I'm begining to think the 450v caps probably would have worked. I
have been living in the solid state world far too long. I stuck a nice
pair of 220uf / 400v caps in each can. Should have at least 1600v
worth of cap. I did wrap a little bit of tape around the whole mess
before I into can so I will cross my fingers.

regards,
Bob