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Problems with Plunger pickups


MarcD
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I'm in the process of building a number of locos which have been designed to have slaters plunger pickups. I'm have a few issues with them operating with DCC. They seam fine for DC but when I wire them up with the control chips nothing happens. I have taken them apart and added extra springs to firm up the contactsbut that has had no effect. Can anyone suggest a way forward?

 

Marc 

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Marc,

 

If it works on DC but not on DCC, it’s not the pickups.

 

Check your wiring!

 

Red to right rail, black to left, orange to motor that was connected to the right, grey to the other motor connection. Absolutely no other connection between motor and track, eg via the chassis. If you have a 21pin decoder, make sure it’s the right way up, some types might go on upside down, and that won’t work.

 

Best

Simon

 

EDIT, I’ll qualify that. If it works, but you get repeated restarts if the sound, it could be dirty wheels, dodgy pickups, or weak pickup springs, but do be careful; increasing the spring tension above the minimum necessary to make consistent contact is only going to cause unnecessary friction & wear out the pickups (and possibly your motor & gearbox too).

 

A possible check - wire a led and resistor across your pickups, and drive the loco on DC or DCC ; if it doesn’t flicker, it’s not your pickups - of course on DC, it’ll only work one way.

 

HTH

Simon

Edited by Simond
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A general tip about installing Slaters pickups - see Jim McGeown's PDF file on the subject on his Connoisseur web site.  Invaluable advice that really should have been included in the instructions by Slaters.  Other than that I think Simon has given you very good advice.

 

Also, on my MOK 14XX 0-4-2T I fitted two pickups on the rear driving wheels.  That and a 17000 microfarad stay alive should keep the loco running!

 

Paul

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I soldered the connections on looks like that could be the problem. Would be nice if slaters updated their instructions. I have 5 locos now that will have to be re wired all have problems and all soldered.

I had thought about just ditching them and replacing them with scrapers.

 

Marc

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I soldered the connections on looks like that could be the problem. Would be nice if slaters updated their instructions. I have 5 locos now that will have to be re wired all have problems and all soldered.

I had thought about just ditching them and replacing them with scrapers.

Marc

I always solder the wire to the brass tag. The secret is to find very fine flexible wire. If using busbars, leave sufficient wire to allow for movement. This free movement is the key to Jim's method.

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I agree with the very flexible wire. Many people who have said to me 'how do you get plunger pickups to work so well', have had a wire that would be good for layout wiring instead of a fine flexible wire, a wire that allows the plunger free movement to 'follow' the wheel rim. I also put a loop in the wire between the plunger and the busbar or copperclad strip. Uprating the spring can cause drag and premature wear so it's a bit of a no-no. I used to sell a wire for the purpose of plunger pick-ups and it was better than the original supplied.

Whilst I'm working in 4mm I have repaired a couple of 7mm locos with the same problem and the lighter wire worked a treat.

 

Dave Franks.

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I use slaters plunger pickups extensively in 7mm and operate in DCC sound.

 

When fitted correctly they are the B`s Knees.

 

Of course if you are using Slaters wheels you must consider their built in wheel tread problem with electrical pickup....

 

post-17779-0-50493900-1526032041_thumb.jpg

 

....and make sure the pickup point does not meet up with that plastic `pyramid` and place the pickup position accordingly.

 

I have never used any major modification to Slaters product but whein I use the connector spades I make sure the nuts are holding it tight and secure the outer nut with either small amount of PVA or better still Canopy Glue ( so they can be removed for servicing etc)

 

I do however tweak the springs length wise so they are the same lenght as the non threaded shaft.

 

post-17779-0-79982300-1526032211_thumb.jpg

 

BUT! as alredy said you must use thin flexible cable/wire. I use tyhe smae gauge as that used on Zimo decoders.

 

post-17779-0-32667400-1526032688_thumb.jpg

 

You can just about see what I use above.....

 

I even blacken Slaters wheels and they are fine......

 

post-17779-0-14858800-1526032636_thumb.jpg

 

....and here they are working fine and only on two axles.....

 

 

....Of course sprung or compensated axles will add greatly to the overall performance...even in   Oh! Gauge   :secret:

 

Cheers

 

John

Edited by ROSSPOP
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I always solder the wire to the brass tag. The secret is to find very fine flexible wire. If using busbars, leave sufficient wire to allow for movement. This free movement is the key to Jim's method.

I forgot to add: if using rim insulated cast wheels, make sure the plunger avoids the insulation!!!

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