Model 70 - Printable Version
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+--- Thread: Model 70 (/showthread.php?tid=17584)
Model 70 - vecher - 11-29-2017
Ok Here is my latest purchase..
[Image: https://farm5.staticflickr.com/4567/24813970128_045524867f_b.jpg]
[Image: https://farm5.staticflickr.com/4576/24813962088_dcb78044c9_b.jpg]
Bottom of chassis really clean..
[Image: https://farm5.staticflickr.com/4580/38654319662_75da625239_b.jpg]
OK so now on to some of the problems found..
Bad on off switch.. No big deal
Bad RF coil.. Primary open.. May have a parts set on the way soon to help with this..
Bad Power Transformer.. Open HV Leads.. Well 1/2 of it open. From CTR tap to one end measures around 120 Ohms.. From CTR tap to other Open..
Bad output transformer.. Primary open.. Have a replacement on the way..
The Field coil is good..
The Big resistor under neath is Good..
Osc Coils appears good Have to do a little more checking on it..
More to follow.. Glad I didn't pay a lot for it....
One Question: Did other radios use the same Power Transformer? Just incase the Parts set Transformer is bad....
Skip...
RE: Model 70 - Ron Ramirez - 11-29-2017
Hey Skip,
That is a model 70, not a 90. I corrected your thread title for you
The power transformer was pretty much limited to Model 70 only. Fortunately, Philco made lots of model 70 sets so it should not be too hard to come up with a power transformer, even if you have to buy a junk chassis to get one. Bonus: a junk chassis might have a good on-off switch.
If you aren't in a hurry, you might very well find a 70 junk chassis next May at Kutztown.
Bad RF coil primary? Rewind it! It isn't that difficult to do.
RE: Model 70 - vecher - 12-02-2017
Quick Question.. Did they use Electrolytic Caps on this? Or not.. Schematic I have shows a + on one side of cap..
Skip...
RE: Model 70 - Arran - 12-02-2017
Skip;
Yes they did use electrolytic caps, and score +1 for this chassis in that it looks like it still has the original cans in place, the larger paper caps (probably bypass caps) are inside those tin boxes under the chassis. I would investigate whether the power transformer actually is bad by removing it and taking the covers off and examining the leads, you have to take it out anyhow if you need to replace it. It's sort of odd to me that even though the H.V secondary is open on one end that the transformer does not look cooked, as in wax and tar leaking out the bottom. I think it may be educational to see if there is a dead short in the B+ circuitry such as a shorted filter cap or bypass cap.
Regards
Arran
RE: Model 70 - Steve Davis - 12-02-2017
I agree with Arran. The Philco 70 power transformers are very robust and seldom fail. It's worth taking a look.
Steve
RE: Model 70 - vecher - 12-02-2017
Ok, I took the transformer out and its still open on one end.. Took it apart and could not find the break All wires look firmly attached..
Weird I know I will look at it again just to make sure..
Skip...
RE: Model 70 - vecher - 12-02-2017
Ok, Rechecked the transformer. The one side is still open . Tried to probe the transformer leads as deep as I could go but still no luck..
Good news is a have a good transformer on the way..
Thanks ALL
Skip...
RE: Model 70 - vecher - 12-03-2017
Next Question Since this uses Electrolytic caps can they be replaced with 10UF Caps.Originals are 6 UF
Skip..
Or I have some 4.7 Electrolytic caps Can I add a Non electrolytic cap at 2.2 UF to come up with 6.9UF would that work?
Skip...
RE: Model 70 - morzh - 12-03-2017
I would keep the first #41 closer to original, maybe film cap of 6.8uF. The #43 can be 10uF or even more , doesn't matter much,as long as it is equal or above 6uF.
Try not to use general purpose electrolytics for the first cap.
RE: Model 70 - vecher - 12-25-2017
Ok,, Some more problems..
Volume Control pot..
How do you open? Seems like the outer one is supposed to be 5K but measuring is flaky .. Can it be cleaned?
[Image: https://farm5.staticflickr.com/4690/27500207139_b1b4b85b4d_b.jpg]
[Image: https://farm5.staticflickr.com/4736/27500205069_6c6819d222_b.jpg]
Thanks
Skip
RE: Model 70 - AudreyHepburn - 12-29-2017
Hey Vecher, would you mind sharing with me any documents you have on this model? We have the same and I'm struggling to find anything other than a schematic. Thanks!
RE: Model 70 - vecher - 12-29-2017
(12-29-2017, 11:14 PM)AudreyHepburn Wrote: Hey Vecher, would you mind sharing with me any documents you have on this model? We have the same and I'm struggling to find anything other than a schematic. Thanks!
Sure.. No problem PM me with your email address and I can send you what I have..
Skip..
RE: Model 70 - Radioroslyn - 12-30-2017
Hi AH and welcome,
Wanted to make you aware that there are two different versions of the model 70. Also if it is CA built it would be model 70A (has bigger power transformer and filter caps)
Info can be found here: http://www.nostalgiaair.org/pagesbymodel/833/M0013833.pdf
GL
RE: Model 70 - TV MAN - 12-30-2017
Vecher, thought this might interest you: http://philcoradio.com/phorum/showthread.php?tid=8626
Morzh (Mike) has an interesting thread on a 70 build also. http://philcoradio.com/phorum/showthread.php?tid=8582&highlight=Philco+70
RE: Model 70 - vecher - 12-31-2017
Thanks I will read all.. Thanks for finding them.. I'm sure they will really help..
Skip...