Starting on 66. - Printable Version
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+--- Thread: Starting on 66. (/showthread.php?tid=10110)
RE: Starting on 66. - morzh - 08-12-2014
Well,
After I soldered everything in place, fixed the speaker (changed the transformer, rigged the new wires) etc, I checked the 5V AC at 80's filament while bringing it on Variac, and then put in the tubes.
The high voltage is OK.
Then I tried the volume....and almost fell off my chair for the radio gave out the loudest squeal! My daughter downstairs got scared, she thought it was one of her toys misbehaving.
The squeal is one tone, and it changes if I switch the tone control to the lower tone.
Which tells me it is an oscillation.
However I do not have shields installed, so who knows. Though why acoustic frequency....
Anyways, good news, speaker and sound obviously function, and the power section is OK.
Oh...and band switch is fully frozen. And it looks clean.
Any ideas as to how best unfreeze it?
RE: Starting on 66. - Ron Ramirez - 08-12-2014
If you don't have a tube shield over the 78 (IF) tube, the radio is going to squeal like crazy.
Make sure it, and the 75 2nd Det-AVC tube have shields in place.
6A7 should be OK without a shield.
RE: Starting on 66. - morzh - 08-12-2014
Thanks, Ron, that confirms my suspiion and gives me hope for tomorrow; I really want this one to sing before I go away on Fiday.
RE: Starting on 66. - Eric Adams - 08-12-2014
Quote:Oh...and band switch is fully frozen. And it looks clean.
Any ideas as to how best unfreeze it?
I have the same problem on my latest 66B Morzh. I put oil down the shaft and have been spraying it with contact cleaner for 2 days. Still nothing.
Until... I just tried something that works!
I heated up the shaft with one of those Butane lighters that I use to light my fireplace and very slowly got it to move by turning the shaft with a small vice-grips. It is still stiff but at least now it moves. I'm sure with more lubrication and more movement it will free up
RE: Starting on 66. - morzh - 08-13-2014
Eric
thanks, will try it with Milwaukee gun, it should be hot enough.
However would be nice to know WHERE it catches. I do not see the obvious place and contacts look clean, plus the chassis did not get much rust so I do not think rust is the reason.
RE: Starting on 66. - Eric Adams - 08-13-2014
It looks like it is the shaft sticking in the housing. My contacts look good too.
RE: Starting on 66. - morzh - 08-13-2014
Have you tried lquid wrench dropped around it then?
RE: Starting on 66. - Eric Adams - 08-13-2014
I've been dripping WD-40 down the shaft. It is still stiff, but I'll just keep moving it up and back until it is free.
RE: Starting on 66. - sam - 08-13-2014
mike try the pb blaster works great
RE: Starting on 66. - Eric Adams - 08-13-2014
Got it, Mike. Rust penetrant and just keep moving it back and forth until it moves freely.
RE: Starting on 66. - Chuck Schwark - 08-13-2014
I use PB Blaster at work. Good stuff.
RE: Starting on 66. - mikethedruid - 08-13-2014
WD40 is pretty lame for breaking loose corroded parts. PB Blaster is much better. You can find it in big pray cans at any auto store. For delicate jobs spray some in a little shot glass and use an eye dropper or brush. One can also spray it on rusted parts and use steel wool to clean off the rust as it eats it away.
RE: Starting on 66. - Eric Adams - 08-13-2014
While WD-40 may be lame, I now have a fully functional band switch.
RE: Starting on 66. - morzh - 08-13-2014
I put some Liquid Wrench inside and in 10 minutes with effort was able to rotate the swith CCW, it was not in BC position.
The radio works, meaning it gets the local station.
It still squeals if the volume is up, even with all three shield installed.
So I still have to find why, which I probably will upon returning from FL end of the month.
RE: Starting on 66. - morzh - 08-13-2014
The volume pot gives me 800K full range i/o 350K.
Paralleled 500K to it...no, still squeals.