Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Antique Radio

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 10-18-2009, 07:49 PM
Mick AV-8 Mick AV-8 is offline
AK Member
 
Join Date: Sep 2009
Posts: 87
Philco 41-285 wiring issue

Hi all working to restore my 41-285 Philco console.
Flipped over the chassis to see under the 84 6Z4 socket..to find out there has been some modifications. Running off one of the electrolytics are some soldered in resistors to the 84 6Z4 socket. There was also a pin cut off the tube when remove?
So not sure how to wire it correctly?
I have an 84 tube with all the pins but I wanted to ask if I should cut out the resistors and wire it another way?
And could one of you comment on the correct way it should be wired?
Not so good at reading the schematics..
everthing else seems to be normal but this socket.
thanks
Attached Images
File Type: gif 84-6Z4-tube.gif (55.3 KB, 28 views)
File Type: gif 84-6Z4-socket.gif (93.7 KB, 38 views)
Reply With Quote
  #2  
Old 10-18-2009, 07:51 PM
Mick AV-8 Mick AV-8 is offline
AK Member
 
Join Date: Sep 2009
Posts: 87
forgot to mention
I put an white arrow on the pin that was cut out..not sure why it was done
Reply With Quote
  #3  
Old 10-18-2009, 11:54 PM
jeyurkon's Avatar
jeyurkon jeyurkon is offline
VideoKarma Member
 
Join Date: Oct 2008
Location: Central Michigan
Posts: 1,698
Check the secondary of the power transformer. One side might be open. Use an ohmeter to mearsure from the center tap to each of the other two taps.

Or maybe one plate of the 84 was shorted and they didn't have another.

I couldn't follow the wiring in the photo.

John
Reply With Quote
  #4  
Old 10-19-2009, 12:34 AM
jr_tech's Avatar
jr_tech jr_tech is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 4,510
It appears that two diodes (not matching) as well as a series resistor (27 ohms) for each diode have been installed between the plate connections of the 84/6Z4 and the filter cap. These diodes bypass/replace the diodes of the type 84/6Z4 (dual diode) rectifier tube. Perhaps one of the plate pins was cut off of the tube to prevent arcing, if the old tube was gassy.

On a 5 pin tube base, pin 3 is the pin with the widest gap between the pins on either side... so (counting CCW around) it appears that pin 2 is the one that has been cut off... is this correct? Then it is indeed one of the plates. Pin 1 which is the next pin around, is one of the heaters for the tube, but looking under the chassis there appears to be NO connection to pin 1, therefore the tube will not light up. The wire to pin 1 may be cut off short somewhere... you will have to find out where pin 1 was connected and restore that connection. It also appears that there is NO connection to pin 4 of the tube. This would be the cathode of the tube, which would normally be connected to the filter cap, had the tube not been bypassed by the two solid state diodes. This connection would have to be restored as well, for the tube to function normally.

Could you scan in a schematic for the set and post it?

Does the radio function ok with the 84/6Z4 bypassed?

jr
Reply With Quote
  #5  
Old 10-19-2009, 06:45 AM
jeyurkon's Avatar
jeyurkon jeyurkon is offline
VideoKarma Member
 
Join Date: Oct 2008
Location: Central Michigan
Posts: 1,698
The schematic can be found here:
http://www.nostalgiaair.org/PagesByM...7/M0013417.pdf

I couldn't tell if one leg of the heater was disconnected or if the wire was dark and matched the bakelite.

John
Reply With Quote
Audiokarma
  #6  
Old 10-19-2009, 08:51 AM
Mick AV-8 Mick AV-8 is offline
AK Member
 
Join Date: Sep 2009
Posts: 87
Looked at it again.
The cut pin on the tube has the electrolytic wire and resistor going to it..it looks fried..and that is the pin that was cut.
The other wire and resistor goes from the same source to the pin above.
I put white dots on the pin/sockets..that have no wire going to them.
So maybe with the help of y'all..you can tell me the correct way it was suppose to be wired..I have another tube with no pins cut..and I could give it a go...
Bulbs lite up..but no sound or sign of life when plugged in...this tube was cold when plugged in.
Not sure why such a cludge was done.
any help or suggestions..is so much appreciated!
I would never get these things going without the help of others..thanks again.
Hope you can comment.

Mick
Attached Images
File Type: jpg philco socket.jpg (75.1 KB, 27 views)
Reply With Quote
  #7  
Old 10-19-2009, 10:36 AM
jeyurkon's Avatar
jeyurkon jeyurkon is offline
VideoKarma Member
 
Join Date: Oct 2008
Location: Central Michigan
Posts: 1,698
Yeah, Jr_tech is right. They're not using the tube at all and substituted diodes.

John
Reply With Quote
  #8  
Old 10-19-2009, 11:46 AM
Mick AV-8 Mick AV-8 is offline
AK Member
 
Join Date: Sep 2009
Posts: 87
So is this the number pin out?
Since I have another tube..I was going to cut out the diodes and resistors.
Good idea or bad?
Those diode,resistor points still have the original wires in place.
No wires though on pin 1 or 4 ..as I understand it.
Looking at the schematic..the green wires go to the heater plates. right?
But it looks like there is a green wire going to #5
I am stumpt to find the correct wires to 1 and 4.
Attached Images
File Type: jpg philco-socket.jpg (81.7 KB, 11 views)
Reply With Quote
  #9  
Old 10-19-2009, 12:27 PM
sean's Avatar
sean sean is offline
VideoKarma Member
 
Join Date: Feb 2004
Location: Sullivan, MO
Posts: 257
The 84/6Z4 is notorious for shorting out as are the earlier 6X5 rectifiers. All of these tubes are electrically equivalent but have different bases. I had the 84/6Z4 in a 1939 Philco short out on me once. On sets that use these rectifiers I have been getting into the habit of disconnecting the rectifier tube from the circuit and replacing it with a pair of silicon diodes and dropping resistors. That way you can leave the tube in place for aesthetic reasons. If you decide to go that route I would replace the silicon diodes currently in your set with a pair that are of the same type. 1N4007 diodes are the typical choice for this purpose.
__________________
Sean - WØKPX
Reply With Quote
  #10  
Old 10-19-2009, 12:48 PM
jr_tech's Avatar
jr_tech jr_tech is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 4,510
I think that you have correctly identified the pin numbers.

I would do a few more checks before cutting the diodes and resistors out of the circuit. Do you have a voltmeter?

1. Can you measure any DC voltage (perhaps 250VDC or so) between the capacitor (+) where the diodes are connected and ground (chassis), when the radio is on ?

2. Pin 5 (still connected) should be one of the heater pins of the tube. Can you measure AC voltage between that pin and ground? If it is 6.3 VAC, you are in luck, and you merely have to ground pin 1 (perhaps to the ground lug on the nearby terminal strip) to get the tube to light up.

It looks like the green cloth covered wires are connected to the PLATES of the tube (pins 2 and pin 3) This will be a fairly high AC voltage, perhaps as much as 500 Volts between the two green cloth covered wires. Be VERY careful, if you try to measure this voltage.

Is the base of the tube charred or is the socket in the radio charred?

jr
Reply With Quote
Audiokarma
  #11  
Old 10-19-2009, 06:55 PM
Mick AV-8 Mick AV-8 is offline
AK Member
 
Join Date: Sep 2009
Posts: 87
reports are in....
Measured DC voltage between cap(+) and diode connections..pin1 is 275-280 and pin3 is 281.
Pin 5 grounded was 5.9 VAC.
ground pin3 was 213AC... ground pin2 was 214AC.... and between the two it was 495AV voltage.
I also ground the pin1 as suggested and the tube lit up..but still no soudns or stations with antenna and speaker hooked up.

So should I replace these electrolytics with new ones and wire them as they are currently?
And proceed to install caps and check along the way?
suggestions and comments....much appreciated
Reply With Quote
  #12  
Old 10-19-2009, 07:56 PM
jr_tech's Avatar
jr_tech jr_tech is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 4,510
Progress is being made! Can you measure between the + of the cap and chassis ground, and between the + of the cap and it's other end ( - ) The cap should have about 250VDC across it.

jr
Reply With Quote
  #13  
Old 10-19-2009, 09:44 PM
Mick AV-8 Mick AV-8 is offline
AK Member
 
Join Date: Sep 2009
Posts: 87
measured (+) cap and ground to chassis it is 251VDC.
Measured (+) cap to other side (-) of cap and it was 271VDC

awaiting further instructions......
Reply With Quote
  #14  
Old 10-19-2009, 10:16 PM
jr_tech's Avatar
jr_tech jr_tech is offline
VideoKarma Member
 
Join Date: Sep 2009
Posts: 4,510
OK it sounds as if the solid state diodes are working ok and producing a decent B+ voltage for the set as measured on the cap. Now this voltage passes through the speaker field coil (part #60 on the schematic) to a second cap (part #27a on the schematic) the second cap should have about 180VDC or so between the + side and chassis ground. If that voltage is not present, it is possible that the field coil is open.

If you can't locate the second cap take another picture that shows a bit more of the wiring, and I can try to spot it.

Does the speaker plug in to an outlet on the chassis or are the wires just soldered to the circuit?

jr
Reply With Quote
  #15  
Old 10-19-2009, 11:00 PM
jeyurkon's Avatar
jeyurkon jeyurkon is offline
VideoKarma Member
 
Join Date: Oct 2008
Location: Central Michigan
Posts: 1,698
I can almost hear the music! You're making great progress with jr tech's help.

John
Reply With Quote
Audiokarma
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 08:19 PM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.