The PHILCO Phorum
New member with 37-650 Questions - Printable Version

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+--- Thread: New member with 37-650 Questions (/showthread.php?tid=22319)

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New member with 37-650 Questions - Chinook47 - 03-22-2021

Hi,

Thank you all for your time and reading my post. I just recently purchased a Philco 37-650 that I'm working to restore. I picked up this hobby mostly because I enjoy woodworking and wanted to restore the cabinet. My first radio I restored a few months ago was a Zenith 8s463. I wasnt sure about restoring the chassis because I never worked with electronics but after receiving a quote for $1700 to recap I decided to give it a try. The chassis was a success and I also installed an MP3 jack. With that I'm starting to enjoy the electronic part over woodworking.

This is all a learning experience for me as I've been trying to read and pickup as much knowledge as I can. I joined this forum because I have some questions regarding this chassis as I have had 2 ECAPS ( c59, 10mfd) explode on me. I'm reaching out for any help to see where I'm going wrong.

All 3 ECAPS (C59,C59A,C57) I have connecting to a terminal strip rather that repacking. All three negatives are being tied together to the bias resistor and the CT. The positive ends of the C57 & C59A I have going to the B+ of the field coil. C59 (which keeps exploding) I have going to chassis ground. I'm still trying to understand positive going to ground. I believe I'm following the print but the results disagrees. In addition I'm noticing the detector, RF & IF tubes are not lighting. The radio wasnt working when I bought it. When I first powered up there was no sound. Could anyone validate my wiring for these 3 ECAPS specifically C59 positive going to ground. 

Thank you all again.

RE: New member - Eliot Ness - 03-22-2021

Welcome to the Phorum Icon_wave

If you post your question under the Philco Electronic Restoration section you'll get more responses. If no one replies before I get back home I'll look up that schematic.

RE: New member - klondike98 - 03-22-2021

Welcome to the Phorum!
Icon_wave

As John mentioned, you can post the electronics question in the Electronic Restorations section.  Keep all of this radios Electronics Question in one thread.

What I see is the negative terminal of C59 goes to chassis ground and the positive terminal goes to the center tap of the transformer secondary.  EDIT: See the info in following posts...re: incorrect schematic.

[Image: https://www.dropbox.com/s/vhqze85ywphcgmy/37-650%20caps.jpg?raw=1]

RE: New member - David - 03-22-2021

   
Welcome to the Phorum, some info from Beitmans

RE: New member - Steve Davis - 03-22-2021

Hi and welcome! 

The schematic is incorrect, the positive end of 59 goes to the chassis and negative to the HV center tap.  Always remember the HV center tap is the most negative point in the circuit.

Steve

RE: New member - morzh - 03-22-2021

It is a mistake in the sch. C59 should have negative to the centertap and positive to GND.

RE: New member - Radioroslyn - 03-22-2021

Hi neighbor

 59 the + connects to the chassis and - to the hv ct. There's not much voltage there so a 35 or 50v cap is fine. No need for a 450v unit.

GL

RE: New member with 37-650 Questions - Ron Ramirez - 03-22-2021

klondike98 Wrote:...you can post the electronics question in the Electronic Restorations section.

...or we can just move this thread there (here). Done. Icon_smile

Welcome Chinook47. I have to ask, but you do not have to answer - who in the world quoted you $1700 to repair/restore your 37-650? That's insane! Good that you decided to repair it yourself. There are lots of good folks here who can help by answering your questions.

RE: New member with 37-650 Questions - klondike98 - 03-22-2021

Thanks for setting me straight on that incorrect schematic!! I should have realized that. Icon_eek

RE: New member with 37-650 Questions - Chinook47 - 03-22-2021

Thank you all for everyone's replies. Everyone is very helpful. I will post my question under the electronic restoration section. Before leaving this thread just to answer some of the questions, first I agree $1,700 to recap was insane. The place was a small business outside of Philadelphia. Lastly, I currently have the C59 positive going to chassis ground but the cap is still exploding. Perhaps my wiring is incorrect.
Thank you all again for your replies.

RE: New member with 37-650 Questions - Radioroslyn - 03-22-2021

Make sure you don't have the - side of 59 connected to the + side of 59A or 57. That will make it go BANG!!! And the 5Y4 will hate you too.

RE: New member with 37-650 Questions - Chas - 03-23-2021

Cap #59 would "explode" if resistor #58 were defective or its ground connection poor. Do not trust riveted ground tabs to work properly after 70 years. Solder 'em or drill out and bolt 'em...

RE: New member with 37-650 Questions - klondike98 - 03-23-2021

Your thread was moved by a moderator so all you need to do is continue with this thread! You are doing great.

RE: New member with 37-650 Questions - Steve Davis - 03-24-2021

Quote:I currently have the C59 positive going to chassis ground but the cap is still exploding. Perhaps my wiring is incorrect.


Was this capacitor ever connected with a reverse polarity? If the cap has been improperly installed it will deform, then if reinstalled correctly, it could still explode.

OT.     I have to ask, did you fly a Chinook?  

Steve

RE: New member with 37-650 Questions - OZ4 - 03-24-2021

Maybe this will help with what's going on with capacitor #59 and why it's looks backwards. 
One would think the chassis is the most negative point in the radio. but no. Redrawing the circuit.
   
As Chas stated if the resistor divider #58 is open the voltage across C59 will rise up alot.