Brain power needed

[DMOD]

Hi Phil ,
I was measuring at the supply output at tb 108 with the supply totally disconnected ( pin 6)
Ac was ridding on the dc.

As for the phase thing I ment to say possibility some type of phase relations to the cathode via the transformer  I really can't finger this out.or maybe a wiring mixup?

Thanks for the feedback Steve.

I think you had a wiring/soldering error.

Either the positive side of the cap wasn't really grounded (maybe cold solder joint?) or there was some previous hacking inside there.

If you still want to use your 8 uF oil-filled cap, you might place it before the filter choke and remove the 50 uF you have there now. I suspect 50 uF might potentially present a high current surge during turn on.

I would measure the capacitance of the 8 uF cap to make sure it really is 8 uF.

10 to 47/50 uF on the right side of the filter choke choke should be more than adequate to reduce ripple, since the choke value is 12 H.

Collin's design philosophy was to overbuild many circuits.

Phil - AC0OB

[KA2DZT]

I've been troubleshooting problems for over 50 years.  First question, when was the last time it work correctly?  Second question, asking the history of the unit.  Knowing the history of any past repairs in most important.

Stu,  your scenario is also possible.  So far, from what we've heard from Steve, the real solution to problem still hasn't been found.

Fred

[W2VW]

I've been troubleshooting problems for over 50 years.

Fred

That's a really long time to figure out a problem Fred.

[KA2DZT]

I've been troubleshooting problems for over 50 years.

Fred

That's a really long time to figure out a problem Fred.

And after fifty years, I'm now working on my second one.  Hopefully this one doesn't take another fifty years.  I'll never get done.

Fred

[kc2hgc]

Hi guys Steve here,

I was to busy with work today did not get to work on the rig.
But here's what we know,
There is 5 volts p-p ac ridding on the dc,
This also can be seen with the scope set on dc,
This is NOT ripple. Ripple would be a saw tooth type of wave or pollsating dc

This gets instresting you know I never did check to see if the 5U4 is rectifing
I'll try that today,And I'll also recheck the transformer volts , and leakage .

However,
Buy changing the caps it cleaned up the ac down to 50mv and completely cleaned the dc.
I have to agree this is not the right way to fix this .
I think Stu your close with the wiring mix up. That's what I met to say when talking with Phil
A kind of a out phase thing going on by not haveing that cap grounded at the right spot.

By the way Stu it's an oil cap.
Ill post more today 73 Steve

[W3RSW]

If you suspect a ground loop see if the 5v pp is on the chassis with respect to AC neutral or real "green wire if modernized " ground.