[Vic Gibson]

Hey All,
Starting on my 37-620 – hope I’m not biting off more than I can chew… I know I’ve read about throwing a tuner in the dishwasher, but seriously? I’m a little leery of that. Is that a serious idea?

Also, I see there are holes where a trimmer caps might be attached and it looks like they might be missing. But the parts layout shows the trimmers underneath the chassis. Maybe it is just an option for another model?
   

[codefox1]

If the trimmers are mounted underneath the chassis and all are accounted for and agree with the chassis, then probably there never were any mounted on the variable capacitor, at least on the side shown in your picture.

Basic Schematic here:
http://www.nostalgiaair.org/PagesByModel...013212.pdf

More complete information available here:
http://www.philcorepairbench.com/schematics.htm

As for the dishwasher, dunno, yours doesn't look that bad. I usually just spray everything with Deoxit, brush gently, use a piece of paper to work crud out of between the rotor and stator blades, let dry, and then lube every bushing/bearing with a tiny amount of lithium grease applied with a toothpick, followed by a tiny amount of WD40 also applied with toothpick.Of course an ohmmeter connected between rotor and stator sections will indicate any problems and where they are as you go from full open to full closed .

[Vic Gibson]

I think I like your Deoxit regimen better. Also, I have an original Riders Vol. VII and it has 4 pages of info on the 37-620. However, it looks like there might be even more info on the Philco Repair Bench link you send. Think I'll order it. How could you have too much info on one of these radios?

[37silverstreak]

I usually soak the unit in a bucket of Extreme Green parts cleaner and hot water. I'll let it soak for a day or so and then use a toothbrush. Rinse with hot water and then use a blow dryer to dry it out completely, then lube the bearings.
Good luck with your project!
Kevin

[GarySP]

For the record, I did use my dishwasher to clean up a very crudded tuner out of my model 20. After washing it I put it in my oven at 175 F for a couple of hours to dry it out completely. Then lubed all friction points. It works fine. Take care, Gary

[morzh]

I did the same for my 20 and my 37-116 tuning caps.
Did not bake them, just let them dry and then greased.

You have to look for the signs of rust on a cap: if it has some, I would not wash it as it will probably get even more rusty being made from something that rusts. Otherwise it is probably fine.

Just don't forget to desolder the grid cap wires first

[marty]

Hi All;
What would you suggest for a Tuner that is rusty arround the PicoFarad Variable adjustment caps ??
THANK YOU Marty

[BrendaAnnD]

For something like that, I remove the adjustment screws (or nuts) and the mica, and gently sand the rusty spots with fine grit sandpaper, then spray it with a greaseless cleaner and reassemble.

[codefox1]

Wow, with all that info, you're all set. Unless it's something else.............

[marty]

Hi All;
Thank You Brenda !! I will try that..
THANK YOU Marty

[Vic Gibson]

Thanks to all for all the great suggestions! What a resource this place is! But, like codefox1 said, "Unless it's something else..." And there always is. So anyway I opted to use Deoxit, toothbrush and dremel tool brush and I'm reasonably happy. Then I decided to measure it (gotta use my new cap. meter). 1st and 2nd sections tuned from 16 pf to about 390 pf. But the last section, when tuned below about 75 pf was OK and then it was erratic the rest of the way up - meter would not hold a value and jumped around + or - 20 to 30 pf or more. But the stator and rotor plates looked clean. However, when fully closed it appeared the outer two rotor plates might have been almost touching the stator plates. I know those things are "vented" or "cut" so they can be adjusted - by who and when I have NO idea. But I bent the ones that didnt quite look right ever so slightly and Presto! I got steady reading all the way through rotation. If I hadnt been messing around cleaning it I never would have noticed that. Here's a question tho: All three sections track +or- 2pf up to about 300 pf. After that they can be off from each other up to 5 pf. I dont like bending those plates and I am guessing that the trimmers will fix that at some point (if and when I get that far). Is that too much tracking variance?

[BrendaAnnD]

5pF is well within range.

[Mondial]

The tracking between sections is really best adjusted after you have the radio up and working. The way I do it is to first align the low and high frequency ends with the low freq osc padder and high freq trimmer so that dial calibration is correct at these points. Then check at frequencies in between and bend the slotted end plates of the osc section so that the calibration agrees with the dial calibration. At a given frequency, you bend the rotor end plates section which is just still meshed with the stator as that setting.

Then align the high freq ant and RF trimmers at the high end of the dial as per the alignment procedure. Once this is done, repeat the plate bending of the ant and RF sections at progressively lower dial freq settings for peak signal until you have the response peaked at all points on the dial.

It is a bit of work, but the increase in sensitivity and performance makes it well worth the effort.

[codefox1]

OMG, priinted dial vs actual once again. Yup, a little nearer or farther on the outside blade can make a bit of difference in accuracy, but it sometimes becomes a battle with the trimmers and the other aging components, not to mention testing instruments.

Enjoy anyway!

[Vic Gibson]

Glad to know that 5 pf variance is OK - sounds right to me anyway... As for bending slotted plates, I admit Mondial's description is the first I've ever read about how and when to do it. And it makes sense. But, I've got a long way to go before even applying power - gonna replace all caps. and check resister values and other things and also clean it up a lot more.

Thanks again for replies.