JimStim V1.4 Voltage Reg

[mrbman7]

Hello,

Can anyone confirm or deny that the voltage regulator on JimStim 1.4 is not supposed to get hot? From the searches I've done i cant tell. I have a complete v1.4 unit and it seems to be functioning correctly however the regulator is getting hot. I just want to know if i need to investigate further. Thanks for the help!

[racingmini_mtl]

The voltage regulator is not supposed to get hot. It may get warm but if it's hot there is something wrong. Have a look at this to see how to troubleshoot the problem.

Jean

[racingmini_mtl]

One thing that is not mentioned in the link I gave above is that you should check that the protection diode (D4) is installed the correct way in. The banded side needs to be away from the DB37 connector.

Also, if you find out that the diode needs replacing, you can run the JimStim without it until you have the replacement. Just be extra careful that you don't have a short on the 3.3V rail because without protection the CPU will be the one taking the hit.

Jean

[mrbman7]

Jean,

Great that really helps! I did remove D4 and the regulator was cool. I guess that I'm not sure how it could have gone bad because it has been hot "out of the box". I guess I could have done something during assembly. Is there any chance it is related to the power supply that I am using? It's DC 14v 800mA which I thought was inside of the spec given on the JimStim assembly page.

is there a way to test the diode on or off of the board?

[mrbman7]

I went ahead and pulled the diode so that I could test it with my digital multimeter on the diode test setting. Strange thing is it tests fine. It reads open circuit in reverse bias and 0.604v in forward bias. Am I missing something?

[racingmini_mtl]

This is a 3.6V Zener diode but they do start to conduct before this. It is possible that this specific diode is on the low end of the spec and conducts enough at 3.3V that a significant current goes through it. Also, it could be that the voltage from voltage regulator is also slightly higher (still within specs) which would increase the current some more.

What you can do is run without the diode (which is what the V1.3 does) or you can replace it. You could also go with a 3.9V Zener diode (1N4730) but this could be too high for the CPU.

Jean