Help with SP140 throttle control board

Howdy all. Can anyone point me to the board circuit layout? In an effort to de-solder the throttle pot I inadvertently destroyed one of the contacts on the board (center contact for the pot). When am I going to start listening to that little voice that said, “don’t do it!”. I want to see if it’s possible to scratch away some of the mask to expose part of the underlying circuit.

My goal was to remove the throttle pot, solder some longer leads and reconnect the pot to a handheld proto I’m working on. As you can see the leads are connected but now when I plug in the battery the control board down by the motor emits a series of loud chirps. I don’t speak chirp well but I’m sure it means, “dummy, you goofed something on the throttle board!”.

I’ve asked info@openppg if a new board without the pot solder on is available but haven’t heard back.

Any suggestions would be much appreciated.

I got looking at the board with a digital microscope and it appears that two of these connections route to the IC3 chip, and the other probably goes to ground. Can anyone confirm this and provide clarification as to which pot pin goes to which IC pin?

Hi Jeff, Those are through hole pads and they are really hard to damage. They have contacts on both sides of the hole. Is there any chance you can fill that hole with solder to get it to make contact?

The pot is more sensitive to heat damage, are you sure you didn’t damage the pot? I unsoldered mine with some low temp solder which is made for unsoldering components. I designed a thumb throttle and mounted the board and display on my gooseneck bar. FYI… I had to use a shielded cable between the board and the pot to stop interference which was causing the throttle to be unstable. I bought a replacement pot that I never used because I thought the instability was a damaged pot. If it turns out that yours is damaged I could sell you the one I bought. I live in North Ogden.

That center pin is 3.3V so if you can’t get solder to stick to the pad you can connect to any 3.3V pin. One option is the top left pad of SWD1. Another option is the connector going to the display (it should be labeled 3V3).

Thanks Paul, I really appreciate the feedback. When l finally got the pot off the board there was a copper sleeve around the center post on the pot, so I assumed that was a good indication that I had goofed that contact. My guess is that the solder that did stick is probably connected to the ground plane, or the pot is goofed, either of which could be causing the beeping. I’ll try connecting the center pin to a 3.3V source as you’ve suggested. Depending on what the cost is for a new throttle board I’ll likely get a replacement. Hopefully I can get what I have to function so I can continue to experiment. Then once I have a functioning prototype I can replicate it with known good components. I’d love to see what you came up with. Also, I had no idea you were a fellow Utah’ern! Good to know! Thanks again.

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