Problems with 524 set up

Radio Telephone and Telegraph Transmitting and Receiving Equipment
Gary Turman
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Problems with 524 set up

Post by Gary Turman » Tue Feb 06, 2018 5:56 am

I'm setting up my M151A1 with a RT 524 radio. When I got everything installed,(except for the antenna unit) without turning on the radio, as soon as I hooked up the power cable to my 1029 mount it started smoking. It is coming from one of the four round parts that separates the top and bottom of the mount. Again I never turned on the power switch on the radio. Removing the radio it does not smoke only when radio installed. I took the mount apart and found nothing wrong. I then tried an extra mount and got the exact same results except I couldn't see where the smoke was coming from. I obviously cut power as soon as I saw this so now it's just a display bit I want a working radio. Thanks for any help.
1941 Dodge WC-7 Command Car
1942 Ford GPW
1968 M151-A1
1967 M416
1945 Gemco 1/4 ton trailer
US Army 1979-1984
Houston Police Officer 1984-2016 (Retired)


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Jeeps4Brains
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Re: Problems with 524 set up

Post by Jeeps4Brains » Tue Feb 06, 2018 9:16 am

So it sounds like the common thing here is the radio. Mounted in both mounts there was a short circuit even though it was not powered up.

What's the history of the radio? When I got my 524 it would not transmit. I had to send it off to be worked on. Haney electronics in Godley Tx.
45' MB, ??' MBT, 47' CJ2A, 48' CJ2A,
51' M38 #1, 51' M38 #2, 51' M100,
52' M37, ??' M101A1 (1st Gulf War Vet),
53' M38A1, 53' M211, 65' M151A1, 67' M416,
MVPA #31724

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W. Winget
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Re: Problems with 524 set up

Post by W. Winget » Tue Feb 06, 2018 9:25 am

If you are using the military wiring harness there are four wires in the cable, these should be branched into two pair, one set is negative the other positive.
If you connected them incorrectly, the radio is the one taking the hit when the power connector makes contact.
Black/Green go together for Negative terminal, Red/White are the Positive terminal Check this and report back.

I would also recommend go over to this page on PRC68.com http://www.prc68.com/I/MT1029.shtml#4720
and read a little more about a switch in the back of your vehicle mount that can be configured to add various pieces, this may be set wrong:

"There is also a junction box that contains an electrical link. This link can be set in two different ways in the D.C. power path.
The E24 terminal is always connected directly to the vehicle 24 volt battery.
The E22 terminal is connected to J22 going to either VIC-1 or COMSEC to switch the radio on or off remotely.
The E23 wire terminal powers the radio. When it is attached to the E24 battery terminal the radio power is controlled only by the radio. When it's attached to the E22 terminal the radio power is controlled by the VIC-1 or COMSEC equipment.
It's unfortunate that the TMs use the term "+25.5 VDC Common" not to mean the ground return for the power supply, but instead to mean a positive switched power buss. This switched DC appears on pin "C" of all four connectors. Pin "B" of all four connectors is the Battery hot terminal. Grounds appear on all for connectors at pin "A".


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Gary Turman
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Re: Problems with 524 set up

Post by Gary Turman » Tue Feb 06, 2018 2:56 pm

Confirmed that I had it wired correctly. The rest is a lot to take in and figure out. Maybe over my head. I recently purchased the radio off an individual who tested it before shipping. Said it powered up ok and broke squelch. Maybe something happened in shipping.
1941 Dodge WC-7 Command Car
1942 Ford GPW
1968 M151-A1
1967 M416
1945 Gemco 1/4 ton trailer
US Army 1979-1984
Houston Police Officer 1984-2016 (Retired)

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W. Winget
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Re: Problems with 524 set up

Post by W. Winget » Tue Feb 06, 2018 4:08 pm

It is coming from one of the four round parts that separates the top and bottom of the mount
Those are merely rubber shock mounts (from memory and photo below, there are 5) unless it's seeking ground through one, and a bolt is loose, it should have zero smoke issue. The radio is grounded through the 4 prong wire as listed above unless it's the really old version (as shown below). Is there some other "four round parts" you could be talking about? a photo of the portion that's smoking would be helpful in distant diagnosis.
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Re: Problems with 524 set up

Post by Gary Turman » Tue Feb 06, 2018 4:35 pm

On the first mount I tried it was smoking and getting red hot from one of the shock absorber assemblies. I don't know where it was coming from on the second mount because it was up under the radio somewhere. I took apart the shock absorber where it was occurring and found nothing out of place. I didn't see any rubber just a mesh type of material. I put it all back together and everything was tight but it did it again.
1941 Dodge WC-7 Command Car
1942 Ford GPW
1968 M151-A1
1967 M416
1945 Gemco 1/4 ton trailer
US Army 1979-1984
Houston Police Officer 1984-2016 (Retired)

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W. Winget
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Re: Problems with 524 set up

Post by W. Winget » Tue Feb 06, 2018 6:07 pm

Need to check continuity of your wires in that power cable, perhaps someone wired it incorrectly, hence a reversal of power into the mount. It would have to be sending power through a bolt into the body via the shock mount for it to heat up, that's just basic physics.
V/R W Winget
Looking for 1918 Standard B 'Liberty' truck parts

Gary Turman
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Re: Problems with 524 set up

Post by Gary Turman » Tue Feb 06, 2018 6:34 pm

Ya, trying another power cable might be the first thing to do. It looks unchanged though. Correct wire colors as you described and the neg side had a yellow band on it indicating so. Maybe a short in it somewhere. I will check it tomorrow and let you know..thanks
1941 Dodge WC-7 Command Car
1942 Ford GPW
1968 M151-A1
1967 M416
1945 Gemco 1/4 ton trailer
US Army 1979-1984
Houston Police Officer 1984-2016 (Retired)

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W. Winget
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Re: Problems with 524 set up

Post by W. Winget » Wed Feb 07, 2018 3:14 am

Pop the back cover off the mount and test the leads as they terminate. Maybe also watch for smoke being let out as you put the radio in it with the cover off, there may be a loose ground there, which then sends the smoke up through the mounting base VS the wire.
Remember, canned Smokes expensive! :lol:
V/R W Winget
Looking for 1918 Standard B 'Liberty' truck parts

Gary Turman
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Re: Problems with 524 set up

Post by Gary Turman » Wed Feb 07, 2018 2:34 pm

Checked continuity on the power cable today. Again, the cable looks unchanged and unmodified. Looks in good condition. The Neg two wires go to "A" and pos to "B" at the radio end. Nothing at C & D. I'm sure the smoke was coming from the mount because I could clearly see where it was getting red hot. That was on the edge of the front left shock absorber.
1941 Dodge WC-7 Command Car
1942 Ford GPW
1968 M151-A1
1967 M416
1945 Gemco 1/4 ton trailer
US Army 1979-1984
Houston Police Officer 1984-2016 (Retired)

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W. Winget
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Re: Problems with 524 set up

Post by W. Winget » Wed Feb 07, 2018 6:05 pm

I'm at a loss here, unless the ground wire is not tight on the battery, possibly causing the ground to run up the mount foot.
Or there is a short in the mount pushing the positive connection down to ground when it's loaded up.
W Winget
Looking for 1918 Standard B 'Liberty' truck parts

Gary Turman
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Re: Problems with 524 set up

Post by Gary Turman » Wed Feb 07, 2018 7:14 pm

So the continuity checked out correctly? Was wondering why I had nothing on C & D
1941 Dodge WC-7 Command Car
1942 Ford GPW
1968 M151-A1
1967 M416
1945 Gemco 1/4 ton trailer
US Army 1979-1984
Houston Police Officer 1984-2016 (Retired)

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Jeeps4Brains
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Re: Problems with 524 set up

Post by Jeeps4Brains » Thu Feb 08, 2018 3:53 am

I still think it is something with the radio. Up in the hole on the radio the mount plug goes into, is there a bent pin or some foreign piece of metal that could cause a short?
45' MB, ??' MBT, 47' CJ2A, 48' CJ2A,
51' M38 #1, 51' M38 #2, 51' M100,
52' M37, ??' M101A1 (1st Gulf War Vet),
53' M38A1, 53' M211, 65' M151A1, 67' M416,
MVPA #31724

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W. Winget
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Re: Problems with 524 set up

Post by W. Winget » Thu Feb 08, 2018 6:02 am

Here's the mount TM, it shows wiring, etc.
http://radionerds.com/images/5/5e/TM_11 ... 1-35-9.pdf
V/R W WInget
Looking for 1918 Standard B 'Liberty' truck parts

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Re: Problems with 524 set up

Post by W. Winget » Thu Feb 08, 2018 7:27 am

If it were sitting in my garage:
I'd pull the positive cable off, set my multimeter for continuity and touch the loose positive wire (B+C combined) and the ground terminal of the battery. It should not "beep" (or if only a meter, show infinity, i.e. nothing)
-Next I would sit the radio on the mount while the meters connected (not shoved in, just resting in the mount as you mentioned it did it when you added weight only I think) no beep?
-Next I would make sure the radio is off, and mount the radio in the mount (should be no beep?)
-Next turning on the radio (battery still disconnected) I should hear a beep (the path from positive to negative being complete now)

If at any point it did not do the above I would look into that step. i.e if sitting the radio on the mount causes continuity, then something is shorting out and needs to be fixed.
From everything you have described it can only be pulling the ground from the mount instead of through the wire. If you unbolted the mount, put it on the ground next to the jeep, then connected the wire and mounted the radio, will it still smoke the mount? You could then measure the voltage by touching the negative battery terminal (24V ground post) to the metal mount and see if voltage is flowing, it should read zero if it went through the wire as it should be.

Not to sound insulting, :) but you are hooking the wires up to the 24 Volt battery setup, i.e. with the grounded to vehicle battery for negative and the second battery's positive for 24 volts....with jumper between the first (grounded battery's) positive post and the second battery's negative post.
(it could happen, I just had to bring it up...)

Why I bring it up: if it's going to the second battery's positive and negative posts, it WILL start smoking, as your in effect pushing 12V ( 1 ungrounded battery) through the wire into a 24V grounded mount! :shock:
This is why photo's help in diagnosing.
V/R W WInget
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Looking for 1918 Standard B 'Liberty' truck parts


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