LGB 51120 acting up

RH Prague

Central European. the station pub is Czech !!
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It is sticking on full power, no matter where the throttle position is. I opened it up and gave it a good clean, and thought that had fixed it, but it is back.

Has anyone else experienced this? What might we look more closely at? Or is it just an ex-throttle.

I must say that when it is described as "able to be left outdoors", that needs to be taken with a pinch of salt. This is my second one.
 
51120.JPG It's been a few years, (Sixteen or so since I dabbled with Analogue!) so forgive the memory, educated guess, if you're getting full power, indicates the power transistor is working, so I'd take a closer look at the potentiometer, would seem the wiper contacts have failed, possibly corrosion from being left outside in the damp.

Could try gentle force, push down on the knob, whilst moving the knob of the pot backwards and forwards, may clear some of the crud from the wiper contacts.

Would suggest if leaving outside, smother the pot with a large dose of WD40!


You'll need a multimeter to check the resistance across the output terminals from the pot.

This link should help with the how a pot works, and to determine if it is still working.........
https://www.ibiblio.org/kuphaldt/electricCircuits/Exper/EXP_3.html#xtocid113035
 
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I can't find the schematic either on Champex-Linden, but actually isn't it there in Arthur Aardvark's post? I just can't open it in full size, and the link Arthur provided does not seem to open.

But we (brother -in-law who understands electrics and I) will follow up your suggestions at the weekend. Thank you both.
 
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