[Ronin61]

Just picked up a 1936 Philco 645 in almost original condition. Two of the large caps on top of the chassis were replaced a long time ago. It has a gigantic transformer on the chassis and seven tubes. After replacing some suspect capacitors I fired it up and it worked pretty good except the volume control will not turn down all the way and won't get very loud. Anyone have any ideas about this condition. Any help would be appreciated.

[morzh]

Logic dictates that if your volume regulation's off the first thing you should do is check your volume regulator potentiometer.

Desolder your #44 (I think) volume regulator and check its operation. See how the resistance between the wiper and the top / bottom ends of the resistive scale changes when you rotate it.
Also see the end-to-end resistance.

The resistors with a tap sometimes develop cracks and the end-to-end resistance becomes infinite or too large.

See how it compares with the nominal value.

Then we'll talk further.

[Radioroslyn]

You also want to replace the non suspect caps too. Definitely the electrolytics in the power supply and all paper caps in the bakelite blocks. After that check the values or the resistors to see if you have any out of spec 20 per sent or so.
The 645 is a nice see! Is it a table model or floor model? Post some pics of it when you get a chance. If it's too tricky here links are fine, I do.
Terry

[Ronin61]

Thanks guys for your input, I will do all that has been suggested then get back to you on the results. I will also post pictures of the cabinet and the chassis. And I forgot to mention that it is a floor model. By the way the dial scale and shadow mask are in perfect condition although dirty. And no I won't use water to clean them just a fine hair photo brush to remove the dust. One more thing, how does this signal strength meter work? Sorry for the rambling but this set excites me and I can't wait to see if it outperforms my philco 42-380.

[Ronin61]

[Image: http://i1281.photobucket.com/albums/a508...96f08f.jpg]

[Ronin61]

the chassis[Image: http://i1281.photobucket.com/albums/a508...451b8f.jpg]

[Ronin61]

the speaker[Image: http://i1281.photobucket.com/albums/a508...9caef2.jpg]

[Ronin61]

dusty but working.[Image: http://i1281.photobucket.com/albums/a508...59608e.jpg]

[Radioroslyn]

Very nice set!!
I almost bought one at a thrift store. They had a deal once a month it would go for half price. I think full price was $120. But someone beat me to it.
A bad audio coupling cap could cause the problem you are having. But it is just easier to go a head and replace the caps rather than trouble shooting each one only to find there all bad.
Terry

[Ronin61]

Well here's what I know so far, both 42 tubes are weak on my heathkit tc-2 tester. One of my 78 tubes is bad with a replacement on the way. Got started on the Bakelite caps, slow but coming along. The 6a7 and the 80 tube I cannot test because my tc-2 doesn't cover them. The set still works great and after repairs are complete will work even better. As you can see in my pictures the grill cloth has a two inch rip in it, I will try to find something that will look presentable. Thanks everyone for your input and suggestions. Philco to the end.

[Radioroslyn]

Are you good at sewing?? or try some heat sensitive adhesive from behind.
GL
Terry

[morzh]

I agree, it is a good piece of grillcloth, and especially considering the scarcity of it today, this kind of damage can be repaired.
This is a good excuse to engage a female companion into one's hobby. Aids bonding too

[codefox1]

Agree. Middle age or younger best.

[Ronin61]

scanned my dial and cut it out with a razor knife. and will be using led's to light it up. already tried the led's and they w[Image: http://i1281.photobucket.com/albums/a508...a4b9fc.jpg]ork great,[Image: http://i1281.photobucket.com/albums/a508...a59aef.jpg]

[Radioroslyn]

I was going to mention that you can clean the dial with odorless mineral spirits. It won't remove the print like water will but do be a little careful.
Terry