Author Topic: Curious problem with my Franken500  (Read 1969 times)

Offline McHeath

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Curious problem with my Franken500
« on: July 01, 2010, 06:48:32 PM »
So I'm happily using my newly cooked up yellow and black frankenphone 500.  It's a mixture of dates and parts, with a 425B network dated 1960.  Everything is going swimmingly until:

Pop.

Heard that sound when I was talking to my son on it today, then the microphone went dead.  Everything else still works, but no microphone.  All the wiring is as D/P has it on his schematic here on the site, and it was working just fine.  But it did make a pop sound and then stopped transmitting sound.

No storms, a clear sunny day.

Any ideas?  I checked and retightened all connections, nothing.

Offline Kenny C

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Re: Curious problem with my Franken500
« Reply #1 on: July 01, 2010, 07:50:40 PM »
take it out and bang it on your leg then try it
In memory of
  Marie B.
1926-2010

Offline gpo706

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Re: Curious problem with my Franken500
« Reply #2 on: July 01, 2010, 08:24:07 PM »
Yes, if its a carbon granule mic a bit "percussive maintenance" might shake it up.
"now this should take five minutes, where's me screwdriver went now..?"

Offline JorgeAmely

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Re: Curious problem with my Franken500
« Reply #3 on: July 01, 2010, 08:33:02 PM »
My initial reply to you was going to be "try your other ear", but you are a nice guy and deserve more than that.

Have you checked the hook switches, tried another microphone, or checked the dial contacts? In a 500, it doesn't go on hook when the mike circuit stops working. Using a DVM, check from screw head to screw head, to make sure the crimps are included in the circuit. I have seen those go bad after moving them around too much.

The microphone should have a relatively low reading of 75 to 250 ohms (from Dr. Meyer's book), but the one I just checked is about 3,000 ohms and works fine. It depends on how much current your meter produces at a particular range. Try tapping it lightly to see if that helps. The idea is that it should not be shorted or completely open.
Jorge

Offline McHeath

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Re: Curious problem with my Franken500
« Reply #4 on: July 01, 2010, 10:08:47 PM »
Good replies folks.  Jorge, your idea of using the VDM to check continuity was dead on, I found that it was the crimps on the red wire.  Guess that happened from being old and being moved and tossed about a bit over the last couple of years in my closet.  Squeezed them down with pliers and we are good as new. 


Offline Dan/Panther

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Re: Curious problem with my Franken500
« Reply #5 on: July 02, 2010, 02:03:11 AM »
Seems like recently I read here some place, that when things go south, try line or handset cords first. Seems to be true. I find the crimp is my most common reason for something not working. So far the only part in a 500 to malfunction on me is a ringer, and that was a Kellogg clone not WE. I still do not know why that phone makes all of my lines go dead ????
D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

Offline JorgeAmely

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Re: Curious problem with my Franken500
« Reply #6 on: July 02, 2010, 12:13:55 PM »
D/P:
Shorted cap?
Jorge

Offline Dan/Panther

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Re: Curious problem with my Franken500
« Reply #7 on: July 02, 2010, 12:57:36 PM »
Jorge;
That would be located in the Network ?
It's a 500 clone so basically just like a WE 500.
How do you test a network for bad components ?
D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

Offline Phonesrfun

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Re: Curious problem with my Franken500
« Reply #8 on: July 02, 2010, 03:42:29 PM »
The ringer cap is located between network posts A and K.  It is a .5 mF capacitor, and the slate and slate/red ringer wires connect to A and K.

If you have a spare .5 mF cap laying around, try removing slate and slate/red from the network posts and hooking them to the spare cap instead, using some alligator clip-leads.  See if that gets things ringing again and eliminates the short.
-Bill G

Offline Dan/Panther

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Re: Curious problem with my Franken500
« Reply #9 on: July 02, 2010, 07:04:29 PM »
Bill;
Got it, I will try that A.S.A.P.
Thanks;
D/P

The More People I meet, The More I Love, and MISS My Dog.  Dan Robinson

Offline JorgeAmely

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Re: Curious problem with my Franken500
« Reply #10 on: July 02, 2010, 09:40:45 PM »
D/P:

The cap in that network should show infinite resistance.
Jorge