Yeah Paul,

I could have missed something in the values of the resistors. I think it's a good idea, re-checking these resistors, so we are not chasing a ghost. I know 1 thing. Those resistors, that I used to replace the candohm, are correct. They are 1% resistors as a matter of fact. I will proceed with doing this and will let you know when I'm finished. You wouldn't know would you, if there's any components mounted physically inside those I.F. cans?

These IF cans contain the transformer and the two variable capacitors that tune the primary and secondary windings to the IF frequency.

They are typically pretty trouble free with regard to problems with the B+ supply. The windings can, and do, go open and lose continuity. This causes issues that creates a whole different range of symptoms with the radio.

You probably don't have much to worry about with them,

Thanks Gary, I will check all resistors. I could have missed something. I will let you guys know.

Well Paul, Gary, phlogiston, and others,

Went through and traced the whole schematic. As I did this, I replaced "ALL" resistors, with the exception of R5, because it's hard to get to. I read it, however, with VOM. And it seems OK.

Still same problem.

I don't know what else to try.

I'm going to re-trace the schematic 1 more time tonight.

I hate to even think of this. But the Power Transformer??????

What do you guys think?

Greg,
Anything is possible, but I don't think I would condemn the PT yet. I don't think your set's symptoms are not consistent with a failing power transformer.

It might be helpful to know the total B+ current load on the power supply and with various tubes plugged in one at a time. You can see this mA reading by breaking the circuit where the rectifier filament connects to the junction of C16 and the field coil. Connect your DVM set to mA at this break in the circuit.

I would record current readings with no tubes, 1 tube, 2 tubes, 3 tubes, etc. Record the B+ voltage as you plug in tubes as well.

OK Paul. Sounds like a very well thought out plan to do this. Couldn't do anything yesterday.
Will proceed today and let you know results.

Paul. Here are my results

TUBE CURRENT (ma) B+Voltage

0.) 0 Tubes in 0ma 0v
1.) 5Y4 3.08 ma 339v
2.) 5Y4+6F6 3 ma (then increases 339v then drops to 160v
to 38 ma)
3.) 5Y4+6F6+6F5 3.4 ma( then increases 328v then drops to 157v
to 40 ma)
4.) 5Y4+6F6+6F5+6H6 (same as #3) (same as #3)
5.) 5Y4+6F6+6F5+6H6+6K7 (same as #3 & #5) (same as #3 & #5)
6.) 5Y4+6F6+6F5+6H6+6K7+6A8 5 ma (then increases 325v then drops to 145v
to 43 ma)

Sorry. I spaced this table out on my original message. But then when I submitted it, it crunched everything together. Hope you cam make it out.

GJENGINGER,

Can you tell us exactly where in the circuit your meters were connected when these measurements were made?

Ted

Here is where I asked Greg to monitor the B+ current...

"It might be helpful to know the total B+ current load on the power supply and with various tubes plugged in one at a time. You can see this mA reading by breaking the circuit where the rectifier filament connects to the junction of C16 and the field coil. Connect your DVM set to mA at this break in the circuit."

Greg,
I am wondering if there may not be a high resistance connection or solder joint in the B+ circuit around the power supply. You may want to check the connections where you replaced R12 candohm earlier. Is the connection of the 125 ohm resistor to ground a good, solid connection? Check the connections of the 27 ohm and 300 ohm resistors, and transformer center tap as well.

The same applies to the connections to the 5Y4 tube socket too. The reason I suspect this because when you plugged in the 6F6 the B+ current came up to what is approximately normal for this tube, but the B+ voltage dropped significantly.

As I said, you need to rule out that there is a high resistance connection in the B+ circuit is dropping the rest of this voltage. Hopefully it is not a connection internal to the B+ winding of the power transformer.

OK Paul. I will recheck all those connections. I will have to do that tomorrow, cause I have to get to bed to get up early. Soon as I check, I will let you know. So I'm assuming you could make out that table ok?

Yes, the table of values was fine.

Paul,

We know what you said. It's actually in an earlier post in this very thread.

Can you tell me what the OP did?

Your suggestion does make perfect sense. However, the resulting numbers being quoted seem pretty strange.

And, I think you failed to tell him where to connect his voltmeter.

I just wish we could just see what's happening on that workbench. I imagine there might be a quick " I see the trouble, right there" if we could.

Ted

Ted,
Wasn't sure how closely you were following the earlier posts in this thread.
I can only assume Greg was measuring where I had asked, but that's not always a given.
I was expecting him to monitor the B+ voltage at the same point his meter was positioned to measure current, although I see now that I did not make that clear earlier.

If this where Greg was getting the measurements, and his voltage is dropping at only 38 ma of current draw, it seemed to me that a high resistance connection somewhere in this area could explain it.

Greg,
Please review the previous posts regarding measuring B+ voltage and let me know where you were monitoring when you recorded these voltages.

Hi Ted & Paul,

Measured across C-16

You should lift one end of C 16 and place the meter in line with it, to complete the circuit, to do your measurements.

The correct method to measure B+ voltage at this point would be positive meter lead to C16 + side and negative meter lead to chassis ground.

Negative lead of C16 is not at chassis ground potential, and will result in an incorrect reading if meter is connected to this point.

Most, if not all DC voltage readings on this set will be with the negative meter lead connected to chassis ground.

If you took your earlier B+ readings across C16, then they should be repeated with the meter leads placed as described above.

Threads like this are what make this forum worth its weight in gold. For relative newbies like me, the education is priceless.

Chin up Greg, you'll get it eventually!

-David