[vecher]

Well, I thought everything was good. I have been running it on a Varaic hooked up to a Isolation Transformer.. Everything is good.. But when I hook up directly to the AC Mains the Eye tube flutters and the current goes up from about 100 Ma to around 400 to 500 ma and it makes a like arching sound...The current probably goes higher but I turn it off when that happens so I do not blow the fuse..

Any clues why?

Skip...

[Eliot Ness]

Did you ever replace the 1626 tube that was showing a short (or swap in a diode)?  If you found two of the Electrolytic caps bad I'd yank out all 4 caps and replace them with 2 caps of (close to) the right rating.  You've also got that .05 cap that could be going bad.

You can pull the 1626 and measure the transformer outputs to verify they are steady when plugged into the wall.

You mentioned once you thought the 1629 eye tube was causing problems, did you ever replace that?

[vecher]

Ok, Let me state this again..

When hooked up to a Varaic and a Isolation Transformer At 120 Volts draw is under .2 amps and all works well..

When hooked directly to either the Varaic or the AC line NO ISOLATION TRANSFORMER as you bring up voltage the current goes to .4 amps and higher and Eye tube flickers and sounds like a arching sound..

So I shut down Do not know how high the current would go.. This all starts at about 90 Volts..

QUESTION... Why does it work with ISOLATION Transformer but doesn't work without...

New 1626 Tube.. New Capacitors..

What am I missing...

Skip...

[Eliot Ness]

Something is shorting to ground when not hooked to the isolation transformer, i.e. when it is not isolated.

......So I put in the 1629 Eye tube.. Powered up on variac.. Tube lit up and was only drawing about .2 amps on AC input.. But then tube started to flicker brightness. Started to smell.. So I shut down.. Nothing was hot underneath or looked like it burnt..

Never blew fuse..

Looks like the 1629 Eye tube is bad or intermittent..

Did you ever replace the eye tube?

[vecher]

No.. I tested it on my tube tester and it looked good..

But I will get a new one to see if that's the problem..

Question is why would it only show up when NO Isolation Transformer is used?

Skip...

[Eliot Ness]

Here are a couple of easy things to try just to see if they make any difference.

Since it looks like someone "improved" this unit by adding a fuse and a grounded power cord, try lifting the green wire off the chassis and see if there is any difference.

You can also try disconnecting one end of the .05 cap that is going to ground.

   

[vecher]

OK Some more.. I measured the AC into the Rectifier tube ( No tube in place) also removed the Eye tube. Measured 500 Volts No current draw.. This is with Isolation Transformer.. With out Transformer It at about 60 Volts starts to Draw around 400 Ma..

Then I measured the AC input leads to Ground.. Each lead read approx 100K to ground.. But noticed something.. The reading would go as low as about 50K then up to 100K as something was charging??

100K to ground sounds not right.. Should it not measure anything??

I disconnected the .05 cap that was from one side of AC to ground No difference..


Skip...

[vecher]

Does anyone have a working C-3 that maybe can try measuring resistance from AC to ground to see if that's what it should Be???

Skip..

[Eliot Ness]

OK Some more..  I measured the AC into the Rectifier tube ( No tube in place) also removed the Eye tube.  Measured 500 Volts No current draw..  This is with Isolation Transformer.. With out Transformer It at about 60 Volts starts to Draw around 400 Ma..

Then I measured the AC input leads to Ground..  Each lead read approx 100K to ground.. But noticed something.. The reading would go as low as about 50K then up to 100K as something was charging??

100K to ground sounds not right.. Should it not measure anything??

I disconnected the .05 cap that was from one side of AC to ground  No difference.....

Are you measuring from each AC input lead to chassis ground or to the ground on the plug?

Skip, remove that green ground wire, or just take off that power cord and install a two lead cord like it had originally and see what happens.  I'd also go through the assembly manual and make sure everything is where it should be and is the correct value:

http://tubularelectronics.com/Heath_Manu...-3/C-3.pdf

Sorry, I don't have a C-3, I do have a Heathkit but it is similar to the IT-11 you just bought.

[Kenneth F. Besso Jr.]

REMOVE---the Ground wire ,,attached to the Chassis----ground is not neutral…..CHEERS

[vecher]

Ok I will try that..

Skip...

[vecher]

Ok, All That worked.. Removing the Ground wire.. Now works with no problem.. with or without Isolation Transformer...

Thats the solution..

But that doesn't answer WHY it worked for many months before.. With Ground wire connected..

Thats the question...

Skip...

[Eliot Ness]

.....But that doesn't answer WHY it worked for many months before.. With Ground wire connected..

Thats the question...

One of your components is breaking down and shorting to the chassis.  If you're lucky you might see some slight arcing in a room with the lights out (and ground hooked up), otherwise you could lift components or take voltage readings across likely suspects with and without the ground wire attached.

I'd pay particular attention to the tube sockets,  grommets and the wires passing through them.  So far you've found a bad resistor, two bad capacitors, a bad 1626, and a suspect 1629.  Try a different 1629 eye tube and you might get lucky.

[TV MAN]

Had a rectifier tube socket go bad on mine and gave about the same symptoms you describe. Mine burned a carbon track between a couple pins on the rectifier tube. Maybe yours is arcing to ground. Pretty high potential on that socket. Found the problem by turning off the lights and watched.