# Need info on RCA Isolation Transformer

N

#### NeoVolt

Jan 1, 1970
0
I got an RCA Isotap II at the flea market on sunday.
I thought,"Wow, cool, a cheap form of variac!" and talked
the guy down to $4 from$20.

I can see that the original power cord was replaced at some
point. The guy selling it had no idea what it was or most of
the other equipment he had for that matter. He had a couple
old HP power supplies, an HP Frequency counter with Nixies
and original manual, some Sencore test equip and various other
goodies. I got the HP Freq Counter for $8 and had a friend test it for me, it works great! One PSU was almost totally burned up inside but the other I got for$9. It works great too!

The RCA Isotap has 2 switches a 2 prong plug socket and 2
small round sockets labeled "Monitor", possibly for meter test
leads. The first switch has 6 positions marked SEC OFF, 25,
50, 75, 100 and 125 for voltage. The second switch has
voltage markings of 0, 5, 10, 15, 20, 25 and that voltage is
added to the voltage from the first switch.

There is a schematic diagram of the circuit on the back of the
unit but some of it is worn off. The problem is that I assumed
( I know it makes an ass out of me) turning switch one to OFF
would prevent any power to the plug socket or the "Monitor"
sockets but instead I measure a voltage of 75VAC from both the
plug socket and Monitor sockets..

I'm wondering if any mistakes were made in replacing the power
cord or if a winding is shorted somewhere.

Could anyone help me out with this? I can not find any
documentation for this thing anywhere.

Neo-Volt

U

#### Uns Lider

Jan 1, 1970
0
There is a schematic diagram of the circuit on the back of the
unit but some of it is worn off. The problem is that I assumed
( I know it makes an ass out of me) turning switch one to OFF
would prevent any power to the plug socket or the "Monitor"
sockets but instead I measure a voltage of 75VAC from both the
plug socket and Monitor sockets..

Have you tried it with a night-light plugged into the socket? Maybe it's
just picking up a few nanoamps from the air... Or maybe someone messed
with the switch.

-- uns

N

#### NeoVolt

Jan 1, 1970
0
Uns Lider said:
Have you tried it with a night-light plugged into the socket? Maybe it's
just picking up a few nanoamps from the air... Or maybe someone messed
with the switch.

-- uns

Just tried it out with a couple NE1's and there's power there.
I guess I'll have to open 'er up.

NeoVolt

E

#### [email protected]

Jan 1, 1970
0
NeoVolt said:
Just tried it out with a couple NE1's and there's power there.
I guess I'll have to open 'er up.

NeoVolt

Don't trust the neons. Plug a 100 watt lamp into it, then
measure the voltage. The neon's have a 100k series resistor,
so they draw very little current. 4 bucks for that is a
really good deal for you!

N

#### NeoVolt

Jan 1, 1970
0
Don't trust the neons. Plug a 100 watt lamp into it, then
measure the voltage. The neon's have a 100k series resistor,
so they draw very little current. 4 bucks for that is a
really good deal for you!

Yep the 100watt lamp did the trick! Thanks for reminding me

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