4MS RCD issue

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gbanfield
Learning to Wiggle
Posts: 12
Joined: Wed Apr 08, 2020 11:22 pm

4MS RCD issue

Post by gbanfield » Tue Jul 28, 2020 10:45 am

]Hey folks, I just picked up a 4ms rcd from a friend as part of a cheerful bundle of random, semi-working euro modules. Yay! Except there seems to be a short or something somewhere shortly after the input. All of the output LED's light up. I've done the following couple of steps to try to figure it out:
1) Cleaning up flux residue (why don't people do this when they build things?!!)
2) I reflowed a couple of dodgy looking joints
3) Testing for continuity and/or resistance from the input onwards for a little bit until it seemed silly doing so without a schematic. I seem to recall that I couldn't get correct measurements from the first transistor, which I assumed was due to it being in a circuit.
4) Reaching out to you folks! Any one have a schematic and/or ideas for where to start? Thanks in advance.



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Whelm
Veteran Wiggler
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Joined: Fri Sep 11, 2015 7:27 pm
Location: West Coast Ish

Re: 4MS RCD issue

Post by Whelm » Tue Jul 28, 2020 11:10 pm

I'll PM you the schematic they sent me when I was trouble shooting mine.

Using the schematic I'd check the IC pins to see if they are sending and receiving the proper voltages.

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stoiker
Learning to Wiggle
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Joined: Sat Mar 30, 2019 3:30 pm

Re: 4MS RCD issue

Post by stoiker » Mon Aug 03, 2020 4:15 am

It looks like the trigger/gate jumper is set to gate. I'm pretty sure my RCD does the same thing when it's set to gate output without an input. Set the jumper to trigger and see if it changes.

PacificState
Common Wiggler
Posts: 70
Joined: Wed May 01, 2013 10:19 am

Re: 4MS RCD issue

Post by PacificState » Mon Aug 03, 2020 9:19 am

Not sure if that photo was taken before or after you cleaned up the joints, but there are certainly a couple of iffy ones under the resistor pack at the top.

Elahrairah
Learning to Wiggle
Posts: 28
Joined: Sat May 02, 2020 12:25 pm

Re: 4MS RCD issue

Post by Elahrairah » Mon Aug 03, 2020 2:45 pm

It's also possible there's nothing wrong physically and the CPU needs reprogramming.

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