[rciancia]

I currently have the transformer out of the chassis. I have a replacement coming Friday and will install it ( after testing it). After installing I will measure all of the readings again before powerup and send a picture of the chassis here.

Thank you !

No sweat, it's how we learn.

Did you verify wire 8 on the transformer to chassis is 325 ohms and not 325K?

Can you upload a picture that shows the whole underside of the chassis?

[jerryhawthorne]

As John said, "it's how we learn". Just one more test when your transformer is out and that would be from any wire on the "pairs" to the transformer itself. Just to make certain we don't have shorts to the transformer frame. The meter should read "open" or infinite.
As John indicated, also re-measure the connecting point you are using for the CT (wire eight) to chassis ground (should be 325 ohms).
Jerry

[rciancia]

The connection point from the CT (- to the chassis ground measures 308ohms.

Testing the transformer as requested, shows all open from every wire to the transformer frame.

The only thing I see wrong with the transformer ( after learning a bunch here) is that I do not have exact balance on either side of the CT. 200ohms and 216ohms seem to not be normal I think.

Here is my chassis. Keep in mind I have to install the transformer, and the Electrolytic Caps yet and replace the two resistors that were wrong. The black wire you see near the power cord is just floating in the air. That is where I attach the negative ends of the Electolytics.

https://pbs.twimg.com/media/B7Rf-UiCEAEKcay.jpg:large

[Steve Chambers]

The 308 ohm reading is ok.

You will not have a balance in ohms. One layer of wire is wrapped around another. What is important are the number of turns not the length of the wire. The outer layer will have to go more distance to give an equivalent number of turns, thus the higher reading in resistance.

That black wire is where the center tap should connect. When the transformer was in the radio did it do so?

Steve Chambers

[rciancia]

Steve

The place where you see the black wire is also where I connect the Center Tap (-. They are on the same connection. Once I get everything reinstalled i will take another picture and upload. My burning question is if the transformer is indeed good, do I have a short somewhere else. I will start probing around the chassis to find out.

[Eliot Ness]

......My burning question is if the transformer is indeed good, do I have a short somewhere else. I will start probing around the chassis to find out.

If your electrolytic capacitor keeps blowing then you either have a short or something is mis-wired.  As I mentioned before  I suspect something has been mis-wired, but you'll have to double check all wiring against the schematic to verify.

You might want to make a copy of the schematic and use highlighters or colored pencils as you verify each wire, component, and connection.

When you get the new transformer compare the resistance reading of the two, yours might be OK.

[LASJayhawk]

Couple more questions.

What do you have for test equipment? Just a meter or do you have more? There are a few longshot tests we could try depending on what you have at your disposal. One thing you could do is check the tubes looking for a short between the big fat pins and the skinny pins. That might find a short in a tube.

Where on the earth are you? It is possible there may be someone here close by that can come over and help you troubleshoot this.

WE WILL FIX THIS. It just takes longer over the internet.

[jerryhawthorne]

Sounds like the power transformer is OK.  Before reassemble, give us a resistance reading from the wire that attaches to your + on the 10mfd cap and goes to the speaker plug (field coil) and from the wire that goes to the 80 filament both to chassis ground.  
Your getting there!
Jerry

[rciancia]

I only have a meter, but if you can suggest another piece of test equipment I would be happy to procure one. I have used a scope many years ago so know how. I am located in Jacksonville Florida btw.


I will do as suggested and trace each wire on the schematic and see if I have one going to the wrong place. I will have another exact unit in my hands tomorrow which I was able to pick up one for parts at a great price so I will be lucky enough to do a stare and compare as well.

I did check the tubes (80, 42 & 77) and no short observed on any pins. Will do that other reading later on Jerry

Thanks Guys

[LASJayhawk]

Either building a dim bulb tester (very easy) or buying a variac so we can bring the line voltage up slowly might be of some help here.

New electrolytic caps burn up if:
They are defective
They are in backwards
They are exposed to higher voltage than they are rated for
They have excessive AC current on them

I'm thinking the last item being caused by a short. Go back and quadruple check the wiring around resistor #22 and #23, where you had a problem before. One end of 23 is almost ground,one end of 22 is B+ Also recheck block cap #24 if it is shorted or mis-wired it would short the power supply out

[rciancia]

Any guidelines on the number of amps needed for the Variac ?

I will build my Dim Bulb tester this weekend.. makes sense.

Either building a dim bulb tester (very easy) or buying a variac so we can bring the line voltage up slowly might be of some help here.

New electrolytic caps burn up if:
They are defective
They are in backwards
They are exposed to higher voltage than they are rated for
They have excessive AC current on them

I'm thinking the last item being caused by a short. Go back and quadruple check the wiring around resistor #22 and #23, where you had a problem before. One end of 23 is almost ground,one end of 22 is B+ Also recheck block cap #24 if it is shorted or mis-wired it would short the power supply out

[jerryhawthorne]

John really did a concise list of what would smoke the 10mfd cap. As fast as it heats up and you have assured us of replacement, polarity and voltage rating it looks to me something is giving them too much A/C. Could be the 80 tube with an unusual internal short but I'm guessing a miss wire or short some where around the 80 tube socket.
Jerry

[LASJayhawk]

A 3 or 5 amp variac is all you would need for radio work.

[rciancia]

Thank you. I have an update.

I put one end of my meter on a known ground and moving around to various point on the chassis I and not getting dead short as I would expect. To make sure I am using the right lingo, I put my meter on continuity testing and in some spots it beeps and goes down to ZERO.. in others it beeps and lingers in the 1,2,5,10ohm space. This leads me to believe I have something not grounded properly or shorted out to ground which could explain my problem. I will systematically remove wires until this condition is corrected.

Fortunately I found a cheap parts unit of the 84 and have a comparison point now.. the new one , has dead short all around.

[rciancia]

Interesting... the testing I have done shows when I clip the wire to the lamp, the rest of the chassis will go down to zero after a beep on the continuity test. My bulb setup is odd... only 1 wire goes to it... on my other chassis, there are 2 wires.. thoughts ?


https://pbs.twimg.com/media/B7gZkSnIcAAX2E9.jpg