Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Model 620 Electrolytic bypass
#5

The filter caps do NOT go to ground. They go from B+ to the top of the large (usually overheated looking) rectifier B- resistors (#70 on schematic). Download your schematic and parts locator from NostalgiaAir.com

Sometimes it helps the radio by connecting an extra 10uuf from B+ to ground, but first the raw filter caps, the ones connected directly to the cathode of the 80, must be replaced.

As mentioned in the other post, you MUST disconnect at least one side of each of the old filter caps. Most restorers do the one-lead disconnect so that the original cap can be left in place for appearances. Leaving both sides connected leads to disaster- and lots of hum.

Pete AI2V


Messages In This Thread
Model 620 Electrolytic bypass - by David B - 01-27-2008, 04:07 PM
[No subject] - by rghines1 - 01-27-2008, 06:41 PM
Philco 620 - by David B - 01-27-2008, 09:12 PM
[No subject] - by planigan - 02-11-2008, 01:23 AM
Filter caps do NOT go to ground - by AI2V - 02-11-2008, 11:18 AM
[No subject] - by planigan - 02-11-2008, 03:31 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Zenith H725
David - I think I understand but what units are you discussing (Low of 1.7, high of 3.9)? Budget constraints for Ham ...EdHolland — 01:43 PM
My Philco 37-116 Restore
You're doing great. I wish I could be more involved, but my mind is right now preoccupied with the reason I am here in ...morzh — 12:21 PM
My Philco 37-116 Restore
Hope you guys are still with me. I have moved on to the alignment. I completed the IF alignment which was pretty muc...dconant — 10:47 AM
My Philco 37-116 Restore
Hello MrFixr55, Thank you for taking the time to explain. I measured 50 volts where you say. Today the 370 volts at ...dconant — 12:51 PM
462ron
Oh that sucks. It’s something easily overlooked. Hopefully it’s nothing more than a resistor! Ron462ron — 08:08 AM
Philco 46-480 Electronic Restoration
Just confirmed that you are correct. It’s the function generator. I connected the signal output probe to one of the inpu...jrblasde — 07:52 AM
Philco 46-480 Electronic Restoration
Ouch, you may be right. Yes, it is solid state. It’s the signal output of my oscilloscope. May be time to crack that ...jrblasde — 07:27 AM
462ron
If you didn’t put a DC blocking cap between the signal generator probe and the plate of the 1st IF it’s possible you ble...462ron — 07:07 AM
My Philco 37-116 Restore
Hi DConnant, The reason why C127 is isolated from ground is because sets of this vintage did not have the center tap...MrFixr55 — 01:07 AM
Philco 46-480 Electronic Restoration
The shield is on the 6H6. It was, in fact, a missing jumper to connect the main chassis ground to the RF chassis grou...jrblasde — 10:58 PM

[-]
Who's Online
There are currently 1041 online users. [Complete List]
» 1 Member(s) | 1040 Guest(s)
Avatar

>