Broken Scroller

[LampyTom]

Hi guys,

I've got some Gelstream scrollers - not sure if anybody is familiar with them or not.

As with all scrollers they have the usual trim-pot for adjusting the string. So you wind the scroller to DMX 0, attach gel strings then wind the scroller to DMX 255 and adjust with the pot so the last frame is in view - or whatever the instructions are for the specific scroller.

Now, one of my scrollers the pot is broken. As in you turn it with a screwdriver to adjust the end stop, but it does nothing. How do I know which type of pot to replace it with? Is it possible or would it have been a proprietary one and as such nolonger do-able?

They were distributed by AC (I believe) and I have all the documentation that AC (UK) have for them - a manual. But it doesn't detail this.


Thanks a lot guys,


Tom

[ajb]

I've never seen a calibration mechanism like that--but then again of only really worked with ChromaQs and SmartColors.

Look at the case of the pot, you should see the value marked. It'll likely be marked, say "10K" to indicate 10,000 Ohms, or it might be marked something like "153". If it's a three-digit code, read it like resistor markings, given "ABC", A and B are the first and second digits, and they're followed by C zeros (so "153" = 15,000 Ohms). There are also various resistance curves (IE, linear or audio taper), it's probably linear, but it either one should work for this purpose.

Once you know the value, you can check if the pot is bad by measuring resistance among the three terminals. you should read the full resistance of the pot between two terminals, and if the shaft is physically centered you should read about half of the resistance from the third terminal to either of the first two.

Once you match the value, you need to match the form factor. I'd check with Mouser first, they have a more useful parametric search than most other suppliers in my experience. Is it soldered to a circuit board, or panel mounted with wire leads?

[wolf825]

You could try to call AC and see if they have a reference list for parts that could be purchased... Otherwise--you could check the actual pot itself for any markings and electrical ratings to match--then you could try places like Newark Electronics or Mouser and see if they have the same thing in thier stock which you then replace it with...


-w

[LampyTom]

Thanks for the replies guys.

Mr ajb, the pot is soldered onto the circuit board - I shall have a look on the pot itself and see if I can see any markings. Failing that I shall pop back and post some pictures of the scroller in question!

I'm sure it only has 2 terminals though (the trim pot) although I could be wrong.