Philco radio chassis type 14
Posts: 15,305
Threads: 530
Joined: Oct 2011
City: Jackson, NJ
OK
I can see how we misunderstood each otehr: by "both ends" I meant "either end to GND". And you read it as "from end to end". Correct?
OK.
So 21 drops 147V and the pin 4 is left with 21V. BTW the 21 resistor should be pretty hot, no?
Can you change 6A7 tube?
PS. Do this: remove 6A7 tube and see what the voltage is at pin 4 now. Should rise up to that 169V or so.
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.
(This post was last modified: 05-27-2016, 07:42 PM by morzh.)
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
With the tube removed pin #4 on the 6A7 tube rises to 180V.
Posts: 15,305
Threads: 530
Joined: Oct 2011
City: Jackson, NJ
Yep. Do you have another 6A7? I am not sure, but I don't think it should draw this much current.
Another thing....it went up to 180V. So the voltage across the 22 resistor without the tube is still about 140V or so? And across 21 is about 0V or so?
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.
(This post was last modified: 05-27-2016, 08:22 PM by morzh.)
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
Well if I measure across the #22 res I get 66.2V, and the 21 I'm still getting 67V.
(This post was last modified: 05-27-2016, 08:49 PM by flatheadjr.)
Posts: 15,305
Threads: 530
Joined: Oct 2011
City: Jackson, NJ
Are you sure you changed caps 20 and 19?
There are no DC paths for either res 21 or 22 with 6A7 removed. The voltages on all 4 resistor's pins should be 320V or so. It should be the same as at the output of 53 choke where 22 resistor connects. Feels almost like the caps are leaky.
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.
(This post was last modified: 05-27-2016, 08:59 PM by morzh.)
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
The #19 is a mica capacitor so I left it, unless it's bad, the #20 received 2 brand new orange dips. Where the choke connects to the 54 I get 320V, the other side is also at 320V, going to the other side of the #22 where it connects to the #20 it drops to 251V, then on the other side of the #22 it drops again to 182V.
(This post was last modified: 05-27-2016, 09:19 PM by flatheadjr.)
Posts: 15,305
Threads: 530
Joined: Oct 2011
City: Jackson, NJ
Could you unsolder the upper pin of res 21 where it meets cap 19 and the coil?
Then measure the drop across res 22 and the voltage on either end of the 22 to chassis?
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.
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
With the upper end of the #21 removed from the coil I now get 320V on the #54 side, and 317V on the #20 side, and if I measure across the resistor I get 0V.
Posts: 15,305
Threads: 530
Joined: Oct 2011
City: Jackson, NJ
Hate to ask but: solder back the 21, bite of the pin of 19 cap that solders to the same spot. Do it so you can solder it back without damaging the cap (leave enough lead). Repeat the measurements. Both 22 and 21 resistors, both ends of each to the chassis. Oh, the tube should be still out.
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.
(This post was last modified: 05-27-2016, 09:47 PM by morzh.)
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
Its doing the same thing as before with a drop each time.
Posts: 15,305
Threads: 530
Joined: Oct 2011
City: Jackson, NJ
Flathead, please, be precise. I do not understand which one "as before", we had a few.
Before as in #36 or #38?
Best is just to list the voltages.
Do you mean #36, where the voltages keep dropping as you go towards the 21 upper end?
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.
(This post was last modified: 05-27-2016, 10:13 PM by morzh.)
Posts: 15,305
Threads: 530
Joined: Oct 2011
City: Jackson, NJ
If this is the case, the last one for today. Lift the upper 21 pin again, do not put the 19 cap back yet.
Measure Ohms from this solder joint (should be only the coil pin left) to the chassis (power off obviously).
You should see infinite. Or in many megaohms. If it is in less than 1Megaohm or so, see if there is ANYTHING else so!dered either to this solder joint or to the tube's panel pin 4.
If nothing, see if there is dirt, charring or anything.
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.
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
Okay I'm finally back, when I measure this solder joint I get around 70k ohms, there is nothing else on the joint. Everything looks clean, no burning or charing that I can see. I tried to take a decent photo but the camera on my phone doesn't focus there very well.
Posts: 15,305
Threads: 530
Joined: Oct 2011
City: Jackson, NJ
Well there's our problem. If there's nothing else and there's 70K it drains the current too much, robbing the voltages.
Nothing? OK. How about you disconnect the tube's pin 4 from the coil and measure the pin to Chassis (ohms again). If pin is clean, then the coil leaks to chassis.
Oh....before you do that. Look if there is a short or low resistance between the tube's pins 4 and 5.
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.
(This post was last modified: 05-28-2016, 12:07 PM by morzh.)
Posts: 135
Threads: 14
Joined: Mar 2016
City: Idaho Falls, Idaho
Okay so I checked the tube first, no short or low resistance there at all. I disconnected the wire from pin 4 and there is no short or resistance between the pin or chassis. I the coil I'm guessing is the problem, and it's been a fear the whole time.
Users browsing this thread: 1 Guest(s)
|
