road show - red's mouth not working

musicman282

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I hope you experts can help me repair my road show pin. Red's mouth isn't working correctly anymore. It runs very slowly and sometimes doesn't run at all. I've swapped the plugs on the H-motor drive board to test the motor and it runs perfectly on the Ted side. I've replaced all the transistors in on the drive board, both the tip102's and tip107's. I also used my scope to make sure I was getting the proper direction and enable signals from the logic boards. I'm pretty much stumped at this point. I tested continuity on all the components. I'm not sure what else to check on this board. I've tried comparing voltages with the driver circuit for ted, but it is kind of hard since it cycles in the test mode as opposed to having stable voltages. It also appears that the quad op-amp chip is producing the correct voltages. Anyone have any suggestions about where to look on this board. I'm guessing that the circuit is just not producing enough current to drive the motor because it is switching directions correctly. Anyone have this problem before? I figured it was the transistors causing the problem. They tested ok, but figured I'd replace them anyways.

Thanks in advance.
 
I ended up getting a replacement h - drive board. I think the schematics in the manual are wrong. That fixed the issue.
 
I ended up getting a replacement h - drive board. I think the schematics in the manual are wrong. That fixed the issue.

Thanks for updating this. I had some dry solder joints on mine which I guess is the shaker adding to it. I was able to improve the issue reflowing some areas but got a new dual h board and problem gone.
 
Since I have posted last I found my problem. It was one of the two Resistors R13 or R27, whichever controlled Red Mouth. I replaced them both due to age, I didn't want the the other resistor to cause the same problem down the road.
 

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