Well, I have been searching for pin voltages for the Philco model 96 tubes. Is there anyone out there that has this information?? Your help would be appreciated. I know I have a problem because I have a voltage of 432V at the 45 tubes but I don't know what the target is. Also why would I be that high. My guess it should be around 250V. I have already changed out all caps and resistors. Thank you in advance for any help.
Hi RH and welcome,
432v is a bit high! A few questions. You are measuring this from where to where?? Is the spkr plugged in?? All tubes inserted and filaments lit? What value and type of caps did you replace the filters (the one in the metal can w/tar).
http://www.nostalgiaair.org/pagesbymodel...013902.pdf
Basically it means you have no current consumption and likely are seeing the unloaded B+.
For the future:
Please tell us exactly where you are measuring: for example "voltage of 432V at the 45 tubes " means very little. While "The voltage from the plate of either of 45 tube to rectifier negative/chassis/etc" means something.
Also: could you measure ohms across the field coil (on the unplugged speaker)?
Terry
If the speaker is not plugged in, wouldn't there be no voltage anywhere on 45 whatsoever?
>If the speaker is not plugged in, wouldn't there be no voltage anywhere on 45 whatsoever?
This is true but just trying to cover all the bases ( a little xsistor terminology!) may have the 80 and the 45's mixed up. They all look the same on that side of the chassis.
I should have posted to measure the resistance across all of the pins on the spkr plug unplugged (going to the spkr not the one on the chassis. All should show some resistance to each other about 2000 ohms of less.
Thank you for your response. Sorry, I went to bed by the time this posted. I am new so be patient with me. I will learn what you guys need. I measured plate (pin 2) to ground on the 45 tubes and I agree with the current consumption thought. Also, I measured with the speaker plugged in. All the tubes in their proper place. I replaced all the caps in the can. 3 -.5 caps, 2-.15 caps, 1 1.0 cap and 2-2.0 caps as per the" Philco Condensers and More" book. I did not quite know if they wanted two .5 caps on pin 1 an 2 in the box or just one attached to pin 1 and 2. I didn't quite understand where you wanted me to measure on the speaker plug but I unplugged it and measured the two pins that go to the plates of the 45s and it was 636 ohms the other two were 353. Do you want me to measure the other two ways too? When I first turn the set on I hear a station and then it fades away as the tubes warm up if that helps.
I forgot to mention. I powered this up without the rectifier tube in and all filaments lit and then I did a full power up. I tested all tubes and they all tested very good.
Just for grins measure the dc voltage from pin 1 -probe and pin 2 +probe on the 45 tube and then do like wise from pin 1 to pin 3. What you got???
There is the part of the speaker #47, the field coil.
One end goes to voltage C, the centertap of the output transformer, and the other goes to cap 43 and resistor 45 at the bottom of the schematic.
This is what I want to ohm out across.
I'm sorry guys I work third shift for a large retailer and we are getting ready for black Friday so I just got home. To answer the first question the pin 1 to pin 2 with the speaker plugged in 310V. Pin 1 to pin 3, 113V.
To answer the second question on ohming the speaker pins. I got 3.397 ohms. from those two pins. Thanks again for trying to help me.
John
Also, I'm wondering if I have a problem with the choke. It ohms out but I'm not getting a very big drop across it. Just a few volts. Should I see more drop here. It is almost full B+ on both sides. 430V in 406V out.
3.3K sounds right.
as for the filter choke, I do not know what "few volts" stand for but it won't drop too much. Typically around 20V, give or take.
And then again, we all think that your current consumption is small, and because of this the dropout across the choke will be small, as it is proportional to the consumption. So your choke is likely OK.
1. How are your 43-45 resistors (the big wirewound?) - are all of them OK? Can you ohm them out?
2. And, forgot to ask: have your checked all your tubes? All of them glow at least?
My tubes are all good with good filaments. They tested better than I expected but you may have found my problem. The #45 tested 7.5k ohms but the #43 will not give me a reading now. I checked all of this before I started the restoration!! What Should I use ohms and wattage to replace this. Also I am going to go ahead and change out the harness that goes around the frame because I found the frame because I found some brittle wires here while poking around. I wanted to preserve this but I may have a short here too. I won't be able to work on this until after Thanksgiving but I would like to know what to change this out with. Thanks for your patience with my terminology. I am a fast learner and hope to get better in the years to come.
John
#43 looks like the off/on switch to me.
Sorry was looking at a 95 diagram
I dunno what it should be Ohms-wise.
If you know the Ohms for the 43 then
Find out from the paper what C voltage shpuld be (use the output tubes plate voltage if not directly shown).
Then add 43 ohms (R43 in Ohms) and 3.4Kohm from your field coil.
Then find out total power:
Ptotal=(C-square volts)/(R43+3400).
Then the power dissipated by R43 is
Ptotal*R43/(R43+3400).
Now use 2-3 times that power for rating of the res 43.
If you go here you can download a schematic that has the values on it. After I downloaded it, it won't let me copy to here or load to photo bucket. It shows # 45 resistor as 8300 ohms.
http://www.schematicsunlimited.com/p/philco