Tuner supports for model 70, now distorted sound - Printable Version
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+--- Thread: Tuner supports for model 70, now distorted sound (/showthread.php?tid=23592)
Tuner supports for model 70, now distorted sound - Jim Dutridge - 06-15-2022
I need to replace the tuner supports for my model 70. Any ideas as to what to use? Renovated Radios does not specifically list anything for the 70.
RE: Tuner supports for model 70 - Ron Ramirez - 06-15-2022
If I'm not mistaken (and I could be
), the 70 uses six two-piece rubber supports. On my Philco model 29, I used three one-piece grommets from McMaster-Carr with rubber flatwashers to increase their thickness.Details here:
https://ronsradios.com/2022/05/02/philco-model-29-45-restoration-part-5/
Correction: Renovated Radios offers original style two-piece grommets for Philco tuners here:
http://renovatedradios.com/product.php?product=320
The listing says it is for most 1933-1936 Philco models. As Model 70 is a 1931-32 model, these may or may not work. Try to measure an old one if it has not turned to powder, and order accordingly.
I don't think Renovated Radios had those in stock when I was rebuilding my Philco 29, as that was around the time the former owner was passing the torch to the new owner.
RE: Tuner supports for model 70 - Jim Dutridge - 06-15-2022
Thanks Ron. I thought about those supports you referenced from Renovated Radios but wanted to see if anyone had another idea. The ones on mine are in pretty rough shape and I'm afraid if I try to remove them they will just disintegrate.
RE: Tuner supports for model 70 - Jim Dutridge - 06-18-2022
While looking thru some of my parts I came across 3 supports that I had ordered from Renovated several years ago that I never ended up using. I don't even remember what i ordered them for but the looked like they were the right height. Took some perseverance but I was able to get them installed and they worked perfect.
Unfortunately after reinstalling the tuning cap and placing the chassis back in the cabinet I found I had no sound at all. Took it back out of the cabinet and flipped the chassis over. Found I had swapped to connections for the tuning cap. I corrected the mistake however I now have very low volume. In fact the local flame thrower station needs almost full volume to hear it.
radio worked with plenty of volume before so I don't know what went wrong.
RE: Tuner supports for model 70 - radiorich - 06-18-2022
Hello Jim,
I hate when stuff goes that way something you thought was a simple fix causing other issues .
Sincerely Richard
RE: Tuner supports for model 70, now distorted sound - Jim Dutridge - 06-25-2022
The problem turned out to be a loose wire connection for the plate voltage to the 1st detector. Now I have plenty of volume but the local stations are badly distorted, even with a short piece of wire for an antenna and low setting on the volume control. Using a longer antenna the distant stations are not distorted when turning up the volume. The IF alignment is dead on. Am I looking at a speaker problem? The cone and surround are rather stiff.
RE: Tuner supports for model 70, now distorted sound - Ron Ramirez - 06-25-2022
It's possible, but first a question -
Is this an early model 70 with the dual volume control (250 ohms and 5000 ohms, wirewound), or the late version with a single 500K volume control?
If the former, some distortion is normal because of the "power detector" used in the early model 70 as well as other older Philco sets. This has been a topic of frequent discussion here.
Are all the tubes good?
RE: Tuner supports for model 70, now distorted sound - Radioroslyn - 06-25-2022
Regrading the speaker issue you may find these two posts helpful. https://philcoradio.com/phorum/showthread.php?tid=22316 and https://philcoradio.com/phorum/showthread.php?tid=21596
As for power detector later on I modified the 370 so the 24A became a pre audio amplifier and used a crystal diode for the detector. In doing this I didn't have to add avc or change the two pot volume control to the circuit as the diode can take up to abt 30v worth of signal. And adding avc is a lot of work and I'm a bum at heart...
RE: Tuner supports for model 70, now distorted sound - Jim Dutridge - 06-25-2022
Ron, this is the early version with the dual control. I did not test the tubes originally but just now I found the 47 was weak and the 27 started out OK then started to fade. I also noticed a tear in the cone and along the surround. Both were not readily noticeable until I slightly depressed the cone. I currently have repairs drying on the speaker and will test it along with 2 newer tubes later tomorrow.
Terry, thanks for the links. I'll peruse them later tonight.
RE: Tuner supports for model 70, now distorted sound - Jim Dutridge - 06-26-2022
Replacing the 2 tubes and the speaker repair has greatly improved the audio quality. Definitely not what you would call great but then I never expected stereo quality. Its what would have been acceptable back in the 30's. I call this project done.
terry, thanks for the links to your speaker repairs but doing that sort of repair kinda scares me. Think I will leave that sort of repair to others.