New member with 37-650 Questions
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Joined: Nov 2012
City: Tehachapi. California
C59 bulged from what voltage? The voltage at C59 should be limited by R58 137 ohms.
It sure sound like it's open between C59 and R58 These two are in parallel. The voltage on one should be the same as the other.
Resistance from HV CT to chassis is 0 ohms. (this is wrong) It should be 137 ohms
-C59A is 0 ohms? This sounds good, The neg side of C59 should be at chassis ground
edit(this is my mistake the pos side of C59 should be at chassis ground)
Voltage across C59A is 500 VDC (this sounds a little high like the tubes are not loading the power supply). Is the radio making any noise?
!!!!!!!!!!!!!!!!!!!RESISTANCE IS FUTILE!!!!!!!!!!!!!!!!!!!!!!
/\/\/\/\/\/\/\/\/\
[Image: http://philcoradio.com/phorum/images/smi...on_eek.gif] Chris
(This post was last modified: 04-05-2021, 11:51 PM by OZ4.)
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State, Province, Country: Pa
The radio is not making noise. The 137 ohms was when I was reading across R58. Unless I'm misunderstanding the instruction on HV CT to chassis, I'm going from CT to chassis is where I get 0 ohms. I went back to take the voltage across C59. It went as high as 170VDC. Also 130 VDC from -C59. The cap just popped again.
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City: Philadelphia
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The 130VDC is chassis to -c59
Posts: 23
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Joined: Mar 2021
City: Philadelphia
State, Province, Country: Pa
I appreciate all the help. I think I will send this radio to the shop or the deep six. I got into the hobby cause I do woodworking and a local shop was going to charge me $1700 starting for recapping. I was pretty fortunate to restore my zenith chassis and cabinet however this chassis seems to have some demons. However, I have learned alot more.
Thank you all again for putting in the time to troubleshoot.
Posts: 285
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City: Tehachapi. California
170v on C59 means that R58 has got to be bad or they are not wired together or intermintant.
I was hoping that my redrawing of the power supply would help.
!!!!!!!!!!!!!!!!!!!RESISTANCE IS FUTILE!!!!!!!!!!!!!!!!!!!!!!
/\/\/\/\/\/\/\/\/\
[Image: http://philcoradio.com/phorum/images/smi...on_eek.gif] Chris
Posts: 23
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Joined: Mar 2021
City: Philadelphia
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I will look into how to replace R58. I think I came across an article stating using terminal strips and resistors. I'll go back and look into that. Also, reading total continuity from CT to negative c59a and c57, would that be a concern? I will go through the print again and your drawing to ensure my wiring is correct. When I first compare your drawing it looked like it matched, however I will give this another look. Also I cleaned and resoldier the joints. I will look at it some more before sending it to the shop. Thank you again for your time and patience.
Posts: 278
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Joined: Nov 2016
City: Cromwell
State, Province, Country: CT
I took a look at your resistance readings and the one where the CT reads 0 ohms to chassis is bad. I would seriously look for a miswire or a short on that wire where it comes out of the transformer.
Do not, I repeat, do not apply power to this radio until the wiring issues are found using an ohm meter. 500 volts across the filter cap has likely destroyed it. Voltage this high means no load which means either a wiring mistake, or bad or unplugged speaker not supplying power to the rest of the set.
At this point all of the filter caps are probably toast. Bulging and shorted caps can damage the power transformer.
If you really want to work on this radio, I suggest printing out a few copies of the schematic in 11X17 and getting a few different colored highlighters. You can trace out different parts of the circuits using different colors. Schematics can be daunting when first looking at them, but if you break them down, not so bad.
I highly recommend watching videos from YouTube member Joernone. He starts on a radio a does a step by step video from start to finish. You will learn a lot from him. He shows how to trace everything on the schematic as well.
Philco 630B restoration video
Hope this helps you out. All is not lost, sometimes you have to step back and go over the basics.
Tony
“People may not remember how fast you did a job, but they will remember how well you did it”
Posts: 23
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Thank you Tony for the YouTube link. I will watch these YouTube videos. Thank you also for the suggestions on enlarging the wiring print. Looking at the print isnt bad. I actually enjoy it. I look at prints mostly everyday in my job, but never in electronics.
I think for now, I'm going to look for additional resources (books) on understanding basic circuitry and troubleshooting. I'm hoping there is one specific to tube radios. I think once I fully understand this, the easier itll be for me to troubleshoot. Your previous thread requesting the values at specific locations had helped. I started to understand why you were asking those questions. If you have any recommendations on basic radio troubleshooting I would truly appreciate it.
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City: Cromwell
State, Province, Country: CT
I also found this web site which might be of help.
Phil's Old Radios
Tony
“People may not remember how fast you did a job, but they will remember how well you did it”
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City: Sneedville, TN
If you are planning to read some good books covering the repair of tube type radios, I suggest these:
Audel's Radioman's Guide by Edwin P. Anderson, preferably one of the 1950s editions.
https://www.amazon.com/Radiomans-Constru...oks&sr=1-2
Elements Of Radio Servicing by Marcus and Levy, a more detailed work on the circuitry used in tube radios. I really like this work because it covers all the theory you NEED, but does so in a clear, concise manner and does not go off into the weeds. I highly recommend buying a hard copy of the book, but it is also available as a PDF online
https://www.amazon.com/Elements-Radio-Se...oks&sr=1-4
https://worldradiohistory.com/BOOKSHELF-...y-1947.pdf
Once you have read these, you will have a good grasp of the basics you need. Be sure to learn all the basic symbols used in the schematic diagrams. That is essential.
And last I'll recommend the very first hard cover book I bought on radio and electronics back when I was about 10 years old, The Complete Book Of Radio by Raymond Francis Yates and Louis Pacent. It was published in 1922, and covers the early development of radio and the theory at the time. The information in it, although very early, is still relevant and valuable. Here is a link to an archive site where you can download an online version...
https://archive.org/details/TheCompleteRadioBook
Have fun ! You're on a new adventure and quest for knowledge.
Posts: 23
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Joined: Mar 2021
City: Philadelphia
State, Province, Country: Pa
Wow, thank you Mike and all for these resources. I will definitely be purchasing these books.
Thank you all for your time and patience.
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City: Wellborn Florida
Another source of info for 10 dollars purchased about 2 months ago. David https://www.ebay.com/itm/How-to-Fix-Repa...SwpdpVaM3u
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