This has been discussed in the Oct. 26th meet thread but I thought I would start something new on it.

To my knowledge, we have had three members (one of them was me) who have had fires in the power wiring between the Tamiya plug and the board connection.

My electronics knowledge is just a bit above non-existent, and I thinks some others have tant problem too, so I was hoping we could collect some info on the problem, and solutions, here.

One of the things I have seen posted is that the HL switch is possibly the problem. (Lack of knowledge showing here) When I look at the HL switch the negative, black wires are soldered to one connection but the positive, red wires have two different connections; can someone please post a diagram of how these should be hooked up to a replacement switch?

Any other ideas of the causes of the fires and fixes would be appreciated.

Glen, there is actually two problems with the typical HL stock wiring and most switch wiring.

1. They use a two pole switch, which is unnecessary, but is more commonly available, and also can be use as a soldering point which leads to the second problem.

2. Both Pos(+) and Neg(-) wiring are in close proximity to each other which will short board/battery/burnt wires and cause fire, not necessary all of them and not necessary in that order.

The reason this is done is simple because both the battery and the connectors to the board all come in Pos/Neg with solder ends, so for production simplicity the train monkey can just solder them to the various point and then you are done (i.e. Pos/Neg from battery to one set of poles and Pos/Neg t the board to the other set).

Basically if you look at a typical switch wiring, if you don't put in sleeves, is about 1-2mm away from frying everything and causing a fire.

There is couple of fixes. Even with the stock wiring, if you take the time to rewire exactly the same way, but put in heat shrink tubing for sleeves, then you are somewhat covered. This does not fix the problem of the switch itself being broken and connecting the two poles as a result however, which I believe is causing some if not all of the problem.

The second fix involves rewiring/addition wiring. You basically have to rewire the stock two pole switch as if it is a single pole switch, and then solder the two black wires together so basically you by pass the Neg on the switch so there is no chance of the switch failing and frying everything. In this case if the switch fails and connects the Pos, all you get is a faulty switch that is on all the time. No damages done.

The third fix involves more re-wiring and creating new JST plug ends and is actually the recommended way of wiring from Clark if you plan on using high draw motors as described on their website. Basically you wired a straight thru battery plug with a JST 2 pin and a Tamiya power on each end and this goes into the Clark Power in directly. You then wire up another straight thru, one 2 pin JST and one to a single pole (or 2 pole doesn't really matter) switch and plug that into the "Switch plug" on the Clark board. Most of us usually would have a pass thru plug into this switch port.

The only problem I find with this last fix is that part of the Clark is now live all the time. Not the whole thing, but there is current on part of the board. So if you don't like that you probably shouldn't use this method.

MikeC.

Mike

Thanks for taking the time to type up a lot of detail on this subject.

MikeC wrote:

The second fix involves rewiring/addition wiring. You basically have to rewire the stock two pole switch as if it is a single pole switch, and then solder the two red wires together so basically you by pass the Pos on the switch so there is no chance of the switch failing and frying everything. In this case if the switch fails and connects the Neg, all you get is a faulty switch that is on all the time. No damages done.

Could you use this option but replace the switch with a better quality, single pole swict, doing all the other things that you suggest, i.e. using shrink sleeves for better insulation?

Would you be able to post a simple diagram for those of us that are challenged?

Of course you can just use any single/double pole higher quality switch, but with the correct wiring, there is nothing wrong with the cheap HL switch even if they do break. When they do it won't fry anything.

Let me see if I can whip up something simple or find something on Google.

MikeC.

MikeC wrote:

Let me see if I can whip up something simple or find something on Google.

MikeC.

Thanks

this will be helpful to everyone  Thanks Guys for posting this

Okay pretty ugly drawings but will do the job. First up is the stock HL wiring:

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As you can see, both Pos and Neg fron the battery is on the switch, so if somehow the switch breaks and the contact is gone, you basically just jump the Pos and Neg of the power source together. there is no reason why they should be on the same switch, regardless of whether the switch is of good quality or not.

The correct wiring using existing HL parts should be like this:

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Pos and Neg do not both go thru the switch. Neg should be wired directed and the switch is only connecting the Pos(+). In this case, if the switch breaks, then it just becomes a passthru and not a fire starter.
The Clark recommended wiring is even simpler as you just wired the battery direct to the clark board, and put a switch on the SW plug. I dont recommend it as it keeps part of the board live all the time.


MikeC.

MikeC wrote:

Okay pretty ugly drawings but will do the job.

The drawings are great

Now I understand the hook up!

Sorry just realized that my diagram is opposite to what I have written down earlier. It doesn't really matter whether it is black or red, as long as your are one going straight thru and one is thru the switch you are okay. I think the custom is to break the red on the switch and keep the black straight thru.


*** Corrected my original post ***

Mike

Is the switch in your drawing in the "On" position?

Glen B wrote:

Mike

Is the switch in your drawing in the "On" position?

Yes. It connects the left and the middle pole together to complete the circuit. The off position would connects the right and the middle pole together which would cut the red connection in both diagram.

Thanks, again, Mike.

I think I will use that configuration.

Good job Mike! Yes, learned to break just one line at the switch the hard way... That's my winter project re-do all my tank switches and yes, just for you no more opening the tank! LOL!

Its the soldered joints causing the issues. Not the switches themselves. As poor as they are.
The standard Heng Long 3 pole switch ( Positive on, Positive off and negative ) is actually a good design but the solder gobs themselves are the issue. I would bet for every short circuit there was had an inspection been done at the solder joint itself it was either a cold solder or the gob was so thick that when the wires got wiggled they short circuited.
Inspect your soldered joints and if they are even close to another joint then de-solder and replace. If the solder joint moves when wiggled then replace it. If the wire moves more than 1/64" away from the solder joint then de-solder. If there is any wires near your solder joint then insulate them.

Well now I can attest to the fact that I do some pretty fine solder and the on one of my switches I felt it kindsa crack and break internally as I was switching it and 1/2 a second later smoke. So I'm not going to screw around with them anymore. big bad butt single pole toggles for me!

I had a broken switch as well that caused shorting and that's when I start looking at re-wiring. The switch basically was live on all three pole. I never like the fact that the soldering is pretty cheesy and Pos/Neg being so close to each other exposed is never a good thing anyway.

Like I said before, if you wired properly even if the switch breaks you still won't get burnt board/battery/wires. As long as you use them as single pole with the proper wiring you are fine. Parts break all the time, you just don't want them to kill other things when they do.

Mike

I just got the replacement Clark into my latest Panther and I did you suggested switch modification.

It works just fine, thanks again for posting it.




I put a bit of heat shrink material over the unused negative connection, for added insurance.

Looks good Glen !

I just did the same modification on my 2nd SS Panzer Taigen Tiger I.

I would have been very sad to have it do some real life smoke and flame effects on the field 

Here are my new switches for the Panther build...