1944 M4A3 105mm

scalawag · Post by **scalawag** » Mon Feb 03, 2014 6:20 pm

Hi Painless,

Just opened up my sherman and taken a pic of the resistor I added. You will have to excuse my scrappy soldering

Sorry it is not a very clear picture. The resistor is fitted in the red cable which leads from the front light to the rear lights. I soldered one end to the front led leg, and the other end to the red lead to the rear lights. The cable in the pic looks black because I put a bit of heat shrink on it to protect the connection. The resistor is a 120 ohm (brown, red brown), as I mentioned before i played about with a few resistor values and settled on this as the best balance.

Hope this helps, and of course if you need more info just let me know

PainlessWolf · Post by **PainlessWolf** » Mon Feb 03, 2014 6:47 pm

Good Morning, Scalawag,
Thank you for the picture. I'll run out to Radio Shack and pick up a resistor of the 120ohm type and solder it into the hot cable that leads from the front lights to the rear lights. It is a well defined hot\ground pair leading from the bow to rear of the tank underneath the driver's side upper hull so I should be able to do this easily (easier than soldering in the LEDs at the rear of the tank were yesterday) I'll report on the results this evening.
regards,
Painless

PainlessWolf · Post by **PainlessWolf** » Mon Feb 03, 2014 7:49 pm

Good Afternoon,
I opened up the Sherman for another look see on my break and the wires, hot\ground, run from both headlights into the mini-board at the front of the tank. From the board, the separate hot\ground goes to the rear tail lights. Any preference for which hot wire gets the resistor? Red into the mini-board from a headlight or Red from the mini-board going to the tail lights?
regards,
Painless

scalawag · Post by **scalawag** » Mon Feb 03, 2014 11:11 pm

Hi Painless,
It should be ok if you put the resistor between the mini board and the hot (red) to the rear lights. That would effectively be the same as mine then.

For some reason h/l did not use a mini board in either of my 2 Sherman's, and used one of the front led legs as the connection point instead

PainlessWolf · Post by **PainlessWolf** » Tue Feb 04, 2014 12:11 am

Scalawag,
Thank you again! I'm off Shift in one hour and am hoping that this is the fix. Over lunch, I de-soldered the tail light connections and made sure that I had hot to positive and ground to black on both of them. I'll re-solder tonight after I test with the resistor. I was able to locate a 100ohm 1/2 watt resistor locally and will use that. The headlights will be a tad bit brighter than yours if this works. I'll be happy. I plan on tinging them yellow to match the searchlight anyway. No idea on why the mini board was used. Maybe your tanks are the way that the HL Sherman will be offered now and the one I purchased was old stock. Taigen should send a note with their version of the RX-18 telling people to get a mini 2 pin connector and use the tail light port that they put on the Board otherwise you will encounter issues like this.
regards,
Painless

ALPHA · Post by **ALPHA** » Tue Feb 04, 2014 2:25 am

Boy Painless your electrical problem is contagious

....after I replied to you ... one of my front LEDs went...taking out the other... disconnected the suspect LED and the other burned bright and clear... needed a replacement

so I pulled the old one out of the hull .... went looking for one in my junk pile.... came across a cool mini board in a helicopter... has mini plugs... all four hooked to led assemblies ..so I too will be doing some electrical work tonight lol....yours better work.. because I have a hunch if yours doesn't mine won't either lol

Take care buddy

ALPHA

PainlessWolf · Post by **PainlessWolf** » Tue Feb 04, 2014 3:28 am

Alpha,
Good luck there with yours. Mine did not work. I am getting current to the tail lights but no go. Once again, testing connectivity, if I clipped the ground of the tester to black then touched the red on one of the rear LEDs, the machine gun light came on and blinked in time to the headlights. The resistor is wired inline between the miniboard up front and the tail lights on the red. It is a 100ohm 1/2 watt so it should have worked. The only thing that I can think is that the replacement LEDs I used were three volts apiece. They are 3mm and slid perfectly into the rear light fixtures and are a perfect size match for the old ones. Either they are too small and need to be 4 or 5mm or the 3s are too big and I need to go 1.5 or 2mm apiece. I am very tempted to just cut the wires for them up front behind the resistor and cap them and put a two pin on them and try them in the searchlight plug to see if they work. That or get a micro two pin and plug them into the port on the Taigen board set aside for tail lights. I think that you have to have a Radio with that function before it will work tho' I will wait to see what advice is given before I buy more bulbs or say *expletive deleted* it and forget about the tail lights.
regards,
Painless

ALPHA · Post by **ALPHA** » Tue Feb 04, 2014 3:39 am

PainlessWolf wrote:Alpha,
Good luck there with yours. Mine did not work. I am getting current to the tail lights but no go. Once again, testing connectivity, if I clipped the ground of the tester to black then touched the red on one of the rear LEDs, the machine gun light came on and blinked in time to the headlights. The resistor is wired inline between the miniboard up front and the tail lights on the red. It is a 100ohm 1/2 watt so it should have worked. The only thing that I can think is that the replacement LEDs I used were three volts apiece. They are 3mm and slid perfectly into the rear light fixtures and are a perfect size match for the old ones. Either they are too small and need to be 4 or 5mm or the 3s are too big and I need to go 1.5 or 2mm apiece. I am very tempted to just cut the wires for them up front behind the resistor and cap them and put a two pin on them and try them in the searchlight plug to see if they work. That or get a micro two pin and plug them into the port on the Taigen board set aside for tail lights. I think that you have to have a Radio with that function before it will work tho' I will wait to see what advice is given before I buy more bulbs or say *expletive deleted* it and forget about the tail lights.
regards,
Painless

Hopefully the LED from the heli is still good... the mini connector board is cook... cut the support out needs to be sanded a bit..should mount up pretty nice ...and cut down on the clutter of the main 11 pin on the SHERMAN
Hmmmmmmmmmmm yours didn't work...did you try jumping the rear to the firing connection... if anything it will be a good troubleshoot to see if the LEDs are functional

Oh.......... ARRRRRRRRRRRRRRRRRRRG your's didn't work !

ALPHA

scalawag · Post by **scalawag** » Tue Feb 04, 2014 7:32 am

Hi Painless, sorry this did not work for you. Mine has the stock leds still so it could be the rating of your replacements. You are right with the resistor it should be ok at 100ohm.

Any chance of some pics of how you have it wired, just to check. I'm not suggesting you have it wrong just that we might be able to spot something to help.

If you have a 2.4ghz taigen system in there (sorry I can't remember what you installed) then you are right the tail light socket is an option too. I don't understand why Taigen put a different sized 2 pin plug on that connection, and I have not used one to know how it functions either.

PainlessWolf · Post by **PainlessWolf** » Tue Feb 04, 2014 7:32 am

65th Day: Alpha, I was still working on it. I salvaged a mini 2 pin connector from a spare 1/24 Sherman M4A3(105mm) turret (oddly enough) and plugged it into the port Taigen provided and tested it on the rear LEDs. Success! For a brief moment, I had four flashing LEDs, front and back and when the tank was turned on, putting it into reverse lit up the rear tail lights. I shut everything down and soldered the connections and turned it back on to test.....No lights, front or back... Thinking that I had mistakenly switched the hot and ground, I unsoldered, resoldered and retried. Still, no lights, front or back. I tried another battery, still no lights. No knowing what else to do, I unsoldered the plug leads and cut the tail lights free from the miniboard. Tested and I had front lights again. I tested the mini port with an LED and it was still working as the 3mm LED lit up when the tank was in reverse. Not wanting to call it a night when I knew I was very close, I decided to try one more time. First, I cut the remaining wire from the miniboard even shorter, salvaged the 100ohm resistor and sealed the hot and ground off. Never know, might need them again one day. Then, I removed the mini 2 pin plug and cut the hot and ground shorter then soldered the wires on it to the hot and ground wires I had cut free from the miniboard and that were still soldered to the tail lights. Crossing my fingers, I plugged everything back in including the mini 2 pin in the Back Up Lamp port. I turned on the tank, flashing front lights and lit searchlight. Very Good. Then I started the tank with the Radio and hit reverse. YES!!!, I had tail lights! Taigen is an odd bird in this respect but now, I can go forward tomorrow with this nasty issue resolved. Here's wishing you luck with your electric build tonight, Alpha. Pics: