AFC shorting switch 38-116
Posts: 49
Threads: 8
Joined: Nov 2008
City: Baton Rouge, LA
My 38-116 chassis is restored except for magnetic tuning calibration.Problem appears to be subject switch stays in shorted position at all times. The contacts are not "welded" together and can be separated with an alignment tool.The switch seems to be a poor design in my opinion but there must be a way to make it work. Am I the first to have this problem? Please help before I fix it with a hammer.
Curtis
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
If cleaning fails to correct the problem, an email to Mark Oppat may be in order...
http://www.oldradioparts.net/
The AFC switches on the 1937-38 Philcos are known to be problematic. These are often stuck in either the "off" or "on" position, or at least the part of the switch controlling the lights gets stuck in either the "off" or "on" position and will not operate.
--
Ron Ramirez
Ferdinand IN
Posts: 49
Threads: 8
Joined: Nov 2008
City: Baton Rouge, LA
Ron, I previously cleaned the switch with deoxit but it did not adequately clean the contacts. So your reply prompted me to use a very small file to brush the contacts. Now the switch works perfectly. Magnetic tuning was easily aligned and 2 stations were set to be tuned using the magnetic tuning feature.Seems to work as Philco intended. Thanks,
Curtis
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
How small a file did you use?
I never thought of that. Great idea.
--
Ron Ramirez
Ferdinand IN
Posts: 1,703
Threads: 55
Joined: Sep 2005
City: Evanston, IL
A relay contact burnishing tool is what is the least "aggressive" for those types of open conacts,
as compared to a small needle file.
I use one with a SMALL drop of De-Ox-It contact cleaner on it. Lightly push the contact leaves
together on the tool and 3-4 in and outs with the contacts held closed usually does the trick.
YMMV
Chuck
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
Chuck
Where would one obtain one of those relay contact burnishing tools?
I have a 40-201 with a pushbutton assembly that is giving me fits. Two of the buttons only work if you hold the button in while holding your mouth just right.
--
Ron Ramirez
Ferdinand IN
Posts: 2,128
Threads: 18
Joined: Oct 2008
City: Merrick, Long Island, NY
A long time ago we used to use a fresh $1.00 bill as a burnishing tool, whilst squeezing gently with a a needle nose pliers. I seem to remember the old master applying a little denatured alcohol before the procedure was performed, an the crud removed from the switch and a tiny amount of lithium grease placed on the shaft. Mind you what was before WD-40 and Deoxit. We used more ridiculous substances in those days to clean things.
Posts: 49
Threads: 8
Joined: Nov 2008
City: Baton Rouge, LA
I used a flat needle file from a set purchased from RS. A drop of deoxit on the file as suggested by Chuck is a good idea but I did'nt think of it.A burnishing tool would be a welcome addition to my tool drawer for use on the next sticky switch.No electronic background here so I don't know where to get one. If I get one I'll store it next to my hammer.
Posts: 1,703
Threads: 55
Joined: Sep 2005
City: Evanston, IL
I'd order a few:
MCM Electronics (no min orders too!)
GC Electronics Part #: 9337 | MCM Order #: 22-910
http://www.mcmelectronics.com/product/GC...37-/22-910
Posts: 49
Threads: 8
Joined: Nov 2008
City: Baton Rouge, LA
Thanks Chuck, I just ordered 5 so I'll be ready for the next dirty open switch.
Posts: 13,776
Threads: 580
Joined: Sep 2005
City: Ferdinand
State, Province, Country: Indiana
Yes, thank you, Chuck; I too will order some in the near future.
--
Ron Ramirez
Ferdinand IN
Posts: 1,703
Threads: 55
Joined: Sep 2005
City: Evanston, IL
You're welcome guys. I use them at work (broadcast tv equipment) on control relays, circuit board socket contacts, switching contacts on 1/4" phone jacks, analogue audio patch bays, etc. The drop of De-Ox-It and the tool keeps 'em running fine.
Chuck
Posts: 2,128
Threads: 18
Joined: Oct 2008
City: Merrick, Long Island, NY
Agree with all. Now, Philco sets probably didn't have switches plated in silver or gold, some equipment did. That's why the very conservative methods were used in the past. If we're dealing with copper contacts encrusted with mouse pee that have lost their tension and sticky shafts, or busted bakelite that needs to be clamped and crazy glued together that's one thing. Switch contacts, just as tube socket parts are sometimes possible to be replaced by donor parts from junkers, but this often involves rather delicate operations to clear the offending area, remove he existing piece, and replace it, and finally epoxy it in place and wait a day or two while it sets up and cures. And eventhen the operation may be successful but the patient dies, but that's how it is.
Posts: 393
Threads: 40
Joined: Sep 2007
City: St Clair Shores, MI, USA
I use thin emery nail boards (very very fine), or emery cloth. Works like a charm.
-Brian
If you collect or are interested in antique telephones, please visit Classic Rotary Phones
http://www.classicrotaryphones.com/forum/index.php
Users browsing this thread: 1 Guest(s)
|
Recent Posts
|
PT-6 antenna connections
|
Notice in the schematic the notch at the bottom of the antenna coil is between pins 3 & 4.
Yes, pin 6 of the 7C6 is...RodB — 07:34 PM |
bridkarl
|
I have two PT-6 chassis. On both there is a blue wire that runs from the above chassis transformer to pin 6 of 7C6. So t...bridkarl — 07:23 PM |
Cannot Adjust an IF Transformer’s cores
|
Joseph, now you are an engineer!!RodB — 06:37 PM |
PT-6 antenna connections
|
Hi, reading your explanation I can see the confusion. If you take it one connection at a time it should result in a desi...RodB — 06:34 PM |
Cannot Adjust an IF Transformer’s cores
|
It works! I received the PCBs this morning in the mail, and put everything together. I reused the base from the original...jrblasde — 04:32 PM |
PT-6 antenna connections
|
I seem to have lost my way on this PT-6.
I see the antenna aerial transformer schematic - I’m reading pins 1 through ...bridkarl — 12:30 PM |
40-150 General questions
|
Good thing you're a good electrician ... the pictures show a lot of rewiring in your future! Take care and BE HEALTHY!...GarySP — 11:52 AM |
40-150 General questions
|
I think RobB has it right. It is a part number and looks like its stamped on the chassis and that wasn't something you ...klondike98 — 11:41 AM |
40-150 General questions
|
It's most likely a part number. Most of Philco part numbers are in that format. I looked at the parts list for this mode...RodB — 08:10 AM |
40-150 General questions
|
Hi Kevin,
No, I don't but I like your Quote about being a good electrician. The way I look at it is "The fact ...MrFixr55 — 08:06 AM |
Who's Online
|
There are currently 3230 online users. [Complete List] » 3 Member(s) | 3227 Guest(s)
|
|
|
![>](https://philcoradio.com/phorum/images/bootbb/asb/right_arrow.png)
|