Philco model 18 (code 121) - HELP! - Printable Version
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Philco model 18 (code 121) - HELP! (/showthread.php?tid=5934)
+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Philco model 18 (code 121) - HELP! (/showthread.php?tid=5934)
RE: Philco model 18 (code 121) - HELP! - Pithicus999 - 07-25-2013
Lot of good stuff here. Morzh and Brenda I see what u are saying. Wow, a 10 watt res. that's pretty big sounds like. All the rest are 1/4 except the big 2 watt dogbone job.
Let me try that.
Jerry, I know was working albeit weakly, and now it doesn't work at all. The speaker is plugged in though.
Thanks.
RE: Philco model 18 (code 121) - HELP! - jerryhawthorne - 07-25-2013
Sorry Pith and others, I missed about measuring across the filter choke. Pith, I noticed you measured the voltage from plate to ground (cathode) on the 42 output tubes and got nada. Just as a test, could you do the same DC measurement from ground to the plate of let's say the 1st IF the 78 if I read the schematic properly.
I ask this for a couple reasons. One is if you were not measuring the choke at the right place ( I would measure across the two e-caps listed as 53 and 54 on the schematic, the two positive leads) only because it is strange to have that choke open up. The other reason is that the field coil being open on the speaker would also give you no voltage on the plates of the 42 output tubes BUT if it was open would allow voltage to the plates of the other tubes in the receiver. If you don't get voltage to the other plates, certainly looks like the choke, which would kill the voltages everywhere.
I hope this makes sense! Just a double check.
If indeed the choke is open and you have no DC voltage on any of the plates of the tubes in the front end, then the resistor idea to replace the choke could become a viable long term solution if you don't want to find another choke. You would need to change the value of a couple of electrolytic caps you have changed to increase their value to add back some filtering of the DC you will have lost as the resistor does not provide the smoothing out of the DC as well as a choke.
If it indeed proves out the choke is bad, you might run a WTB in the classified section and perhaps someone has one on a parts chassis.
Good luck and check in. Your learning a lot. Again, the other people responding are a lot smarter than me. Before I go off to look for what might be an expensive part I want to make certain I have done every test to assure I'm correct.
Best of luck and post a couple pictures in the clubhouse of Ireland. One place that is on my bucket list to visit.
Jerry
RE: Philco model 18 (code 121) - HELP! - Pithicus999 - 07-29-2013
...working on this currently...thanks for the help everyone.
Also, I'll post some pics of the trip, where (or How do I) in the 'clubhouse' thing you mentioned Jerry? I'm assuming that is on this site?
I want to also try Brenda's suggestion so I'll need to run to the big@ss electronics store that is 45 mins from my place.
RE: Philco model 18 (code 121) - HELP! - Ron Ramirez - 07-29-2013
The "clubhouse" here is called Old Ron's Bar & Grill. I'm Old Ron, proprietor, bartender and bouncer.
Find it here:
http://philcoradio.com/phorum/forumdisplay.php?fid=14
RE: Philco model 18 (code 121) - HELP! - Pithicus999 - 07-29-2013
Thanks Ron!
RE: Philco model 18 (code 121) - HELP! - Pithicus999 - 07-30-2013
Hey Jerry,
The DC measurement on the #78 tube (P-K) was 6 volts. And the measurement across the 2 ecaps was 0.3 volts.
RE: Philco model 18 (code 121) - HELP! - jerryhawthorne - 07-30-2013
Sorry Pith but I guess I wasn't clear on the measurement across the two e-caps, I was looking for resistance. Might be easier to check from each to ground for some high DC voltages (power on). If you get good HV on the first one but nada on the second, it certainly looks like the choke has gone bye-bye. If you use the resistance scale at the same points as previously listed, across the + of the two caps (power off) you should get the value that Brenda suggested for a replacement resistor.
Your voltage measurement on the plate of the 78 certainly points to the choke being open.
Regards, Jerry
RE: Philco model 18 (code 121) - HELP! - Pithicus999 - 08-01-2013
I'll check the measurments out when I get home.
I figured out that photobucket thing. Here are pictures from Austria, Ireland, and Slovakia from my trip last month.
If you need a password to see them use 'pithicus'. These are only a few of them, I think I have about 800.
http://s1346.photobucket.com/user/tjlesondak/slideshow/
RE: Philco model 18 (code 121) - HELP! - Pithicus999 - 08-01-2013
If you have trouble....it might be easier to copy/paste the link into a new tab then to click on it.
http://s1346.photobucket.com/user/tjlesondak/slideshow/
RE: Philco model 18 (code 121) - HELP! - jerryhawthorne - 08-01-2013
Worked for me pith and nice pics.
Jerry
RE: Philco model 18 (code 121) - HELP! - Pithicus999 - 08-02-2013
I need some help with what size/rating/watt transformer to buy that will replace this #51 filter choke.
All I see on the schematic is [166 Ohm and part #32-7115]
Here is what I'm looking at for a match: http://www.tubesandmore.com/search/node/filter%2Bchoke
Thanks.
RE: Philco model 18 (code 121) - HELP! - jerryhawthorne - 08-02-2013
Pith per your PM, if bypassing that choke with some heavy resistors still didn't yield any B+, time to look a little more carefully at the situation. Either the bypass was not in the proper location or you have some other problems.
Jerry
RE: Philco model 18 (code 121) - HELP! - morzh - 08-02-2013
I am not sure what the PM was about but in case it was about low voltage after the resistor, coupled with the opened choke that hints to some sort of overload.
Imply disconnect the choke's output or your resistor, if you connected it already, and measure the resistance to GND/Chassis, if it is to low ormaybe even shorted.
RE: Philco model 18 (code 121) - HELP! - Ron Ramirez - 08-02-2013
You may want to seriously consider contacting the Michigan Antique Radio Club to see if someone is willing to give you some hands-on assistance with that set. While we are perfectly willing to do what we can, there is only so much one can do via the Internet, and there comes a time when some one-on-one help is in order. Just a thought.
RE: Philco model 18 (code 121) - HELP! - Pithicus999 - 08-02-2013
Thanks for the advice Ron. I did go to a meeting they had last fall, it was a big radio convention in Livonia. I met a few people but none lived very close to me. I'll reach out to them again, maybe someone will be willing to help.
As far as the low voltage, I took Brenda's advice and connected a resistor to the two ends of the filter choke to complete the circuit. I soldered the points in and re-measured the P-K volts across the #42 tube.
The measurements prior were 0.00 volts and after putting in the resistor they were 0.02 volts...not a real big jump.
In any case, assuming I do need a new filter choke, how do you assess which one to buy if the parts list on the schematic is not conclusive?