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

37-650 console
#1

Hello Could anyone tell me what the plate voltage should be on the 6J5? Then what would the voltage be before and after resister #7 51k  ohms. The schematics I have do not show what it should be and I only have -1.25.  Then passes through resister #34 1m ohms to #7 resistor 51k and end result is approximately .200 to .300 millivolts not sure if this is correct.  Thank You  paul 
#2

Hi Paul & Welcome.
I would suspect that your plate voltage on the 6J5 is going to be very low. If the 6J5 was used as an audio amp it would require much more voltage, but it isn't. It's used as a diode to convert the RF signal to audio and to develope AVC voltage to control the gain RF and IF stages.
The voltage should change as signal is applied to the antenna.  The alignment and the condition of the tubes will also have an effect on it too.
Terry
#3

(04-10-2015, 02:21 PM)Radioroslyn Wrote:  Hi Paul & Welcome.
I would suspect that your plate voltage on the 6J5 is going to be very low. If the 6J5 was used as an audio amp it would require much more voltage, but it isn't. It's used as a diode to convert the RF signal to audio and to develope AVC voltage to control the gain RF and IF stages.
The voltage should change as signal is applied to the antenna.  The alignment and the condition of the tubes will also have an effect on it too.
Terry

Hello Terry. Thank You I am not getting any stations at all and was looking at the tube voltages as a start and it wasn`t listed on the Riders schematic. I am going too recheck the wafer switches. But they seem ok all the other tube voltages are good. Checked all the coils and read through them but still can`t get a station Broadcast or short wave. paul
#4

Hi Paul,
The 6J5 probably not my first thing I'd look it. Lets try some easy troubleshooting. Take a transistor radio and set the dial at 1500kc. Place it near the 6A8 tube or the band switch. Tune the Philco between 1000kc to 1200kc. If all is well you hear the local oscillator in the transistor set. Will sound like loud hum. Do you have a signal tracer or signal generator?? What have you done to the chassis so far??
Terry
#5

Hello I got the radio working some what. I can pick up a few local stations and a lot of short wave. I found (through researching pages of posts written on these forums pertaining too the 37-650) that one of the band switch jumper wires was slightly grounded to the mounting post of the band switch. Had to pull out the antenna section too find and fix it. Put everything back together and it came too life. But now I believe I have another ground in the broadcast section ( which I already had pulled out too rebuild it had a short that was sparking) when I put my finger on the 6K7 RF tube the radio gets louder and picks up more stations. I am currently reading 2 meg ohms on the broadcast band coil secondary to chassis and it also is reading into the antenna stage secondary. I will desolder the coil wires and try too trace out where the ground is coming from. Thanks for the help and any suggestions. paul
#6

Hello The 2 meg ohms I was reading on the coils was ok. It was coming from the two i meg resisters 34 and 35. Can`t find a ground in either the broadcast section or the antenna section. The local stations come in fine but distance stations only come in when I put my finger on the 6K7 cap. Any advise would be appreciated. Thanks paul
#7

So what do you get for resistance across the red and black antenna terminals on the back of the chassis? With the band switch in the BC position.
Terry
#8

Hello Terry. I have 1.4 ohms. From red to chassis 1 ohm and black to chassis 1 ohm which seems fine. I have to go to work will check back around 4pm est, would rather work on radio but duty calls. paul
#9

I'm not interested the red or black to gnd. What is the resistance across the red and black(to each other).
Terry
#10

I think he said 1.4 Ohms.
In any case if both have low to GND, it will be possibly twice that across.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#11

Hello I have 1.4 between the Red and Black. The red and black to ground reads through the center tap,and I thought that may be of interest also. Thank You paul
#12

Hello. Well how about this the secondary of the broadcast antenna coil terminals 4 and 5 are only reading 5.2 ohms instead of 6 ohms the schematic shows. Would this cause a power loss and loss of reception on distance stations. Thank You paul




Users browsing this thread: 2 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 3885 online users. [Complete List]
» 1 Member(s) | 3884 Guest(s)
Avatar

>