800 Series Radio- Battery Drain

[Jim Neville]

Hello all. Finally got around to seeing why my radio was not working in my '50 Windsor. Found that the speaker wire and power wire were not connected. Radio works! Yahoo! After having her out for a drive I pushed the off button on the radio and parked it. 3 days later went out to go for a drive and the battery was completely dead. My question is would the radio still draw current from the battery even when parked? Would setting up a battery disconnect prevent this? Thank you.

[Sniper]

Typically, the radio is wired to a switched source, so if you did that the answer should be no. 

[busycoupe]

Perhaps there is a short in the radio and thatis why the power wire was disconnected.  However, as Sniper says if the radio was connected to ignition switch it should not get any power when the switch is off.

[keithb7]

My '53 Windsor had two different portions of the radio. The head unit with the tuner that had its own power supply and tubes.  Then there was the amplification unit. It too had it's own power supply and tubes. This was located at the speaker area. Is it possible you have this style? The tuner could be wired to the ignition switch. Yet the other power unit could wired directly to the battery.

 

A clamp style multi meter that reads DC amperage is a great tool for troubleshooting this. You can check the amp draw to the radio when the key is off. If it's not the radio, you can carry-on and check other wires to find the amp draw. It's a good tool to own.

 

https://www.amazon.ca/UNI-T-Current-Capacitance-Resistance-Measurement/dp/B01FNMCA6Q/ref=sr_1_100?crid=W2M6EBZ43DYB&keywords=DC+Ammeter&qid=1662042594&sprefix=dc+ammete%2Caps%2C157&sr=8-100

Edited September 1, 2022 by keithb7

[Jim Neville]

Thanks Keith. I'm slowly picking up tools that I thought I would never need. I just disconnected the radio until I can figure out why my battery went dead so quick. These 'olde Mopars are sure a money pit but lots of fun! After charging my battery I took it out for a spin and now the fluid drive tranny won't shift. Any ideas as to why? Watched all of your YouTube videos. Love it!!

[DonaldSmith]

The M5 and M6 transmissions are wired differently, but in each case, the circuits are energized for first or third gear, and for the downshift. The shop manual should have the appropriate wiring diagrams.  I found on my M5 that the fuse holder on the relay was at fault.  But you don't have a relay. 

 

For the M6, Current comes from the ignition switch to a post of the coil, and then through a circuit breaker to the solenoid (under the floor) and to the anti-stall device (at the top of the carburetor) . 

 

With the key on, one or both of the posts of the anti-stall device should be "hot", as tested with your handy voltmeter or test light. .   

 

I

[Bryan G]

Check that idle speed isn't too high; check that the wires to the carb are intact. Recently I had a plug wire too close to the kickdown wire; the resulting short caused the transmission to drop into 3rd. 

 

My radio isn't wired through the ignition, though I plan on changing that someday. On mine, the power switch had burnt out. It controls 2 circuits, both the dial light and the radio itself (the latter draws quite a bit of current.) Some models just ran everything on the same circuit. I tinker a lot on old radios so dug around my junkbox but couldn't find a correct switch, only one for a single circuit. I experimented with using modern headlight relays which were easy to tuck inside the radio; the idea was to save wear on the replacement switch, while also allowing the dial light to still be on only when the dash lights were powered. A 12v relay is marginal down around 6v and I found them unreliable so switched it back to just using the switch to control the radio directly. Anyway, I was having an issue where the radio wouldn't turn all the way off. I found that if I turned the dash lights on and then back off, the radio would cut off. I guess it was back-feeding somehow. After I did away with the relays it hasn't done that.

[MarcDeSoto]

Also, be aware that MyMopar.com has the old dealer mechanic filmstrips and booklets that taught the dealer mechanics how to service your car.  

 

https://mymopar.com/mtsc-1949-volume-2-12-how-to-service-the-hydraulically-operated-transmission/