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Heathkit Cap Tester C-3 - Printable Version

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Heathkit Cap Tester C-3 - vecher - 05-19-2017

Heathkit Cap Tester C-3..Went to turn on this evening.. It didn't.. So took apart.. Someone had added a Fuse in the primary of the transformer.. It blew.. Replaced fuse and it Blew again.. So Here is schematic..

[Image: http://i292.photobucket.com/albums/mm38/wb4yvo/heathkit%20C-3%20036_zps6opcyfcs.jpg]

I measured the following..

Red to Red/Yel 1559 Ohms
Grn to Grn/Yel 170 Ohms
Yel/Yel 2.4 Ohms

Primary Blk to Blk 1.0 Ohms..

Nothing looks burned underneath.. Question Looks like they are using a 1626 Tube for a Rectifier? WHY??

I did pull tube and tested on Tube tester It did show a short when I pressed short button.. Could tube have gone bad??

I do not have another one to try.. Are there any subs I could use??

Skip...

RE: Heathkit Cap Tester C-3 - Radioroslyn - 05-19-2017

< Question Looks like they are using a 1626 Tube for a Rectifier? WHY??

At that time it was a cheap war surplus tube. Their tracers use 1629's for the same reason.

> Are there any subs I could use??

1N4007 But replace the two 8mf caps, that's what took out the 1626.

RE: Heathkit Cap Tester C-3 - vecher - 05-20-2017

I will take a picture of the underneath.. Looks like the caps were replaced.. But they used 2 caps in series at 22 UF 450 Volts to get 11 UF They did this to both ..

I have some 10 UF 450 volt Caps Or 10 UF 250 Volt caps..

This has been working fine for many months since I got it.. I just turned it on yesterday and it didn't work..



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RE: Heathkit Cap Tester C-3 - morzh - 05-20-2017

The 0.05uF cap in the primary could be bad....

RE: Heathkit Cap Tester C-3 - vecher - 05-20-2017

I will check..

Thanks
Skip..

RE: Heathkit Cap Tester C-3 - Radioroslyn - 05-20-2017

1 ohm seems awful low for the primary resistance. Didn't see the decimal point at 1st.

RE: Heathkit Cap Tester C-3 - vecher - 05-20-2017

I will double check it

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RE: Heathkit Cap Tester C-3 - vecher - 05-20-2017

Ok, Here is bottom Picture

[Image: http://i292.photobucket.com/albums/mm38/wb4yvo/heathkit%20C-3%20003_zpsxt3del2x.jpg]

Looks like they did a nice job..

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RE: Heathkit Cap Tester C-3 - vecher - 05-20-2017

Ok Remeasured the Primary Now got 56 Ohms.. Maybe I measured wrong the first time?

I do not have a 1626 Tube so I cannot try to put in a good one..

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RE: Heathkit Cap Tester C-3 - morzh - 05-20-2017

They are using a triode as a rectifier.....

RE: Heathkit Cap Tester C-3 - vecher - 05-20-2017

Ok, This is what I did next.. Pulled the 1626 and the 1629 tube. Powered up on variac and got approx 500 volts AC between red and Red/Yel leads.. So that looked good.. No current drawn..

Next put in 1626 tube.. Powered up on variac and got about 180 or so volts B+.. Current draw small at about .10 Amps..

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..

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RE: Heathkit Cap Tester C-3 - Radioroslyn - 05-20-2017

Pull out the 1626. Solder in a 1N4007. Banded end to pin 8 other end to pin 3. This will replace your 1626 that you said was shorted. That might be what is causing the eye to flicker. Also check the 1M resistor on the back of the eye tube, that's where it's get it's HV to light the target (eye tube screen).

RE: Heathkit Cap Tester C-3 - vecher - 05-20-2017

Ok I will try.. Do I need a Resistor to drop voltage down to 150 Volts? Or will the diode do that..

If I need Resistor What value and wattage?

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RE: Heathkit Cap Tester C-3 - Radioroslyn - 05-20-2017

I don't see anything that is particularly voltage critical. You've got 900v worth of filters. The eye tube can run up to about 300v. Nominally at 20ma of load about 1.2K @ 2W will drop 25V if you want to lower the voltage. Not quite sure what the total current is for this circuit. It isn't much.

RE: Heathkit Cap Tester C-3 - vecher - 05-30-2017

Ok, Finally got around to this again. I found a 90K 1% Resistor that was shorted.. I didn't think they did that.. Also found 2 of the Electrolytic caps were not operating correctly..They were supposed to be 450 Volt caps but could only handle about 250 volts.

So replaced the Resistor and caps and measured the B+ now at 150 Volts .. Everything is now working correctly..

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