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jamest

Think before you act! - OO Heljan Hymek

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Hi,

 

I think I have made a mistake in trying to improve the running of my second hand purchase.

 

It was running ok and smooth...if a bit intermittent - so I thought a wheel clean and re-tweak of the pickups would help.

 

I picked off the bottom cover and removed the wheels - being careful to keep the axles in the same place - but, possibly crucially, I did not insure that I did not turn the wheel set 180 degrees. So what was the left wheel of a set could now be on the right - if you see what I mean.

 

After adjusting the pickups outwards (possibly a bit too much really) I re-assembled (not realising the possible error mentioned above) and tested on DC. It ran better, not perfect, but better.

 

I had already tried it on DCC too before my bodging - and it was ok, but no better. But when I tried it on DCC after my work the chip started to smoke and died after only a few inches of travel!

 

My question is - what potentially did I do wrong that could have induced such an error? Would swapping over the wheels left and right cause this?

 

Regards,

James

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22 hours ago, jamest said:

Hi,

 

I think I have made a mistake in trying to improve the running of my second hand purchase.

 

It was running ok and smooth...if a bit intermittent - so I thought a wheel clean and re-tweak of the pickups would help.

 

I picked off the bottom cover and removed the wheels - being careful to keep the axles in the same place - but, possibly crucially, I did not insure that I did not turn the wheel set 180 degrees. So what was the left wheel of a set could now be on the right - if you see what I mean.

 

After adjusting the pickups outwards (possibly a bit too much really) I re-assembled (not realising the possible error mentioned above) and tested on DC. It ran better, not perfect, but better.

 

I had already tried it on DCC too before my bodging - and it was ok, but no better. But when I tried it on DCC after my work the chip started to smoke and died after only a few inches of travel!

 

My question is - what potentially did I do wrong that could have induced such an error? Would swapping over the wheels left and right cause this?

 

Regards,

James

Hi,

 

I haven't taken the top of my Hymek yet but its possible when the 8pin DCC connector went back in some of the pins may have touched the metal chassis beneath or pierced wires beneath. If so you could try putting a piece of electrical insulation tape beneath the decoder socket and carefully putting a new DCC decoder in (checking for wiring faults first).

 

Regards

 

Nick

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I've moved it into DCC questions to hopefully get some other input.

 

I've just looked inside one of my Hymeks and can't immediately see any reason even if the axle/wheel insulator was the other way round (best practice would be to make sure they're all on the same side though) so I think Nick's closer to the answer.

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1 hour ago, NIK said:

Hi,

 

I haven't taken the top of my Hymek yet but its possible when the 8pin DCC connector went back in some of the pins may have touched the metal chassis beneath or pierced wires beneath. If so you could try putting a piece of electrical insulation tape beneath the decoder socket and carefully putting a new DCC decoder in (checking for wiring faults first).

 

Regards

 

Nick

 

I haven't had this issue with any of my Hymeks, but it was definitely an issue with the first run of BRCW3's, so maybe it could be the cause.

 

Mike.

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Hi,

 

I don't think getting the wheels the wrong way round should cause the DCC decoder to overheat as it is downstream of the pickups.

 

Most  OO Heljan diesels have the wheels insulated both sides from the axle.

 

Regards

 

Nick

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Thanks Chaps,

 

I have other Heljan hymeks and I noted their wheel arrangement - there is a small 'boss' diameter on one side as the axle enters the wheel. As others have said it might not be a problem, but I have re-arranged them as per the factory examples anyway.

 

I've not been brave enough to try another chip again yet - but I will watch out for the chip/blanking plate socket. If I'm honest I could well have pushed down on the socket while I was hacking away at the underside! That would explain it working ok before my intervention. I did notice that the blanking plate and chip where relatively loose fits in the loco socket anyway.

 

I might return it to my local shop (where I got it) explaining all this as he is very good with second hand stuff - and he was not sure how 'good' the loco was when selling it.

 

thanks again.

 

Regards,

james

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While I haven't experienced this, there have been past reports of the undersides of the decoder sockets touching the metal chassis and causing momentary shorts. adding a bit of electrical insulation tape will preclude that from happening. Something like that may have caused your decoder smoking.

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Hi James

From first had experience - always check a loco on the programming track when you have fitted a chip. 

Any problem investigate do not risk ful DCC power until you can read OK.

Norman

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