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

Philco 645 Hum-m-m-m
#9

Prior to applying power, I replaced all electrolytics, paper caps (tubular and Bakelite blocks), and any questionable resistors; checked every coil including the speaker for continuity and appropriate resistance; and tested all tubes for transconductance and emissions.

I believe I have wired everything correctly, but (you may find this hard to believe) I have actually made mistakes in the past. I can read a schematic pretty well, but when I get befuddled I resort to sketches.

[Image: https://lh5.googleusercontent.com/-r8rVl...520645.JPG]

The BC resistor and condensers 58, 59 were particularly troubling because the condensers has been replaced with a couple of cardboard electrolytics under the chassis, so the physical wiring was changed from the original. I also wasn't sure which end of the resistor was +, -, B, or C. I rebuilt new cans for 58 & 59, and rebuilt the 3-condenser can.

This is a before/after comparison. All replacement components are reproductions.

[Image: https://lh6.googleusercontent.com/-ihp5d...520645.jpg]

The power resistor has three terminals. On this picture, numbering the terminals from left to right as 1, 2, and 3; can you give me a designation for each terminal? I think I connected the middle one as C-. As for C58 and C59: I think the negatives are connected to the BC resistor and the positives to opposite ends of the field coil. The Philco schematic doesn't indicate (+) and (-) on the electrolytics.

I have to pull the chassis again, then start verifying my connections and check that I don't have any reversed polarities on the electrolytics.

Thanks for the help. It'll take me a few days to check out everything you've mentioned.


Messages In This Thread
Philco 645 Hum-m-m-m - by Winky Dink - 04-07-2014, 07:21 PM
RE: Philco 645 Hum-m-m-m - by gregb - 04-07-2014, 07:24 PM
RE: Philco 645 Hum-m-m-m - by Warren - 04-07-2014, 08:05 PM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 04-07-2014, 08:23 PM
RE: Philco 645 Hum-m-m-m - by Ron Ramirez - 04-08-2014, 04:31 AM
RE: Philco 645 Hum-m-m-m - by morzh - 04-08-2014, 09:10 AM
RE: Philco 645 Hum-m-m-m - by PAradiogeek - 04-08-2014, 10:16 AM
RE: Philco 645 Hum-m-m-m - by TA Forbes - 04-08-2014, 12:26 PM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 04-08-2014, 11:54 PM
RE: Philco 645 Hum-m-m-m - by TA Forbes - 04-09-2014, 09:58 AM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 04-09-2014, 12:45 PM
RE: Philco 645 Hum-m-m Fixed? - by Winky Dink - 04-12-2014, 09:43 AM
RE: Philco 645 Hum-m-m-m - by Steve Davis - 04-12-2014, 10:36 AM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 04-12-2014, 10:57 AM
RE: Philco 645 Hum-m-m-m - by TA Forbes - 04-12-2014, 11:04 AM
RE: Philco 645 Hum-m-m-m - by BrendaAnnD - 04-12-2014, 03:18 PM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 04-13-2014, 04:14 AM
RE: Philco 645 Hum-m-m-m - by morzh - 04-13-2014, 08:28 PM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 04-14-2014, 12:29 AM
RE: Philco 645 Hum-m-m-m - by morzh - 04-14-2014, 07:23 PM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 04-16-2014, 03:28 AM
RE: Philco 645 Hum-m-m-m - by morzh - 04-16-2014, 09:30 AM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 04-16-2014, 03:24 PM
RE: Philco 645 Hum-m-m-m - by TA Forbes - 04-16-2014, 03:43 PM
RE: Philco 645 Hum-m-m-m - by morzh - 04-16-2014, 04:05 PM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 04-17-2014, 03:54 AM
RE: Philco 645 Hum-m-m-m - by morzh - 04-17-2014, 07:54 AM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 04-18-2014, 12:08 AM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 07-02-2014, 10:20 PM
RE: Philco 645 Hum-m-m-m - by Arran - 07-02-2014, 11:21 PM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 07-03-2014, 12:53 AM
RE: Philco 645 Hum-m-m-m - by morzh - 07-03-2014, 08:45 AM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 07-03-2014, 11:37 PM
RE: Philco 645 Hum-m-m-m - by morzh - 07-05-2014, 10:09 PM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 07-06-2014, 12:57 AM
RE: Philco 645 Hum-m-m-m - by morzh - 07-06-2014, 07:58 AM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 07-06-2014, 08:30 AM
RE: Philco 645 Hum-m-m-m - by morzh - 07-06-2014, 09:16 AM
RE: Philco 645 Hum-m-m-m - by Winky Dink - 07-07-2014, 07:04 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Jackson 715 not working
Mrfixr55, its working now. I cleaned the switches and sockets with spray cleaner. Thanks for helping on this one.daveone23 — 06:26 PM
Jackson 715 not working
Now that you posted the schematic, I don't know why that Sprague electrolytic cap is across the meter, as it is not indi...MrFixr55 — 05:51 PM
HiFi (Chifi) tube amp build - but my own design.
What may be lacking in the PP Tube amps may be the 2nd harmonics, which some, especially RCA back in the day called &quo...MrFixr55 — 05:32 PM
Jackson 715 not working
Usually in an emission tester, the tube under test is measured as if it were a diode. So, some testers connect all the g...RodB — 04:17 PM
Restoring Philco 37-604C
Yep. F5 is green, D5 is Red. Red is Bad. Green is Clean.morzh — 01:30 PM
Jackson 715 not working
I did start to do that but I stalled out because I could not figure out how the grid and plate get voltage. In this diag...daveone23 — 11:52 AM
Restoring Philco 37-604C
(Insert Homer Simpson "DOPF" Here.) When all fails, look at the can. Took the Ron Ramirez advice, red Caig D...MrFixr55 — 09:23 AM
Philco 91 Speaker Replacement
From your text I am not sure if you intend to use the existing speaker with a resistor instead of the field coil. It wo...morzh — 08:44 AM
Philco 91 Speaker Replacement
My field coil is bad. I am still hoping to find an original, but if I can't I will go with a fitting Philco speaker, 125...dconant — 08:34 AM
Philco 91 Speaker Replacement
As Rod said, it is OK to use a fitting speaker, and then look for an original one. If you buy a Hammond 125 output tr...morzh — 08:15 AM

[-]
Who's Online
There are currently 3920 online users. [Complete List]
» 1 Member(s) | 3919 Guest(s)
Avatar

>