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Dan Francis

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Good news is I completed a 4.2.4 and it works perfectly! Even did the SMT components myself. Bad news is I burned up my trusty 4.0. I was trying to put an RJ45 jack in place of the separate servo/blower connections. I had done the servo mod a long time ago and it has always worked fine so I had the correct wire locations. The only thing I can think of is that since the 4.2.4 shares a ground between the blower and servo I thought I could do the same with the 4.0 and used the blower ground for both blower and servo. When plugged in it worked wonky for a while, the blower would never turn off, then quit all together. The rPi now gets very hot in one spot and the whole heatermeter is dead. I wanted the RJ45 jack output so I could use the 4.0 and 4.2.4 interchangeably. Solder points looked fine so ground is only thing I can think of. So the question is would the shared ground on the 4.0 be the problem? I, of course, know nothing of electronics. Thanks. Dan
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The HMv4.0 used a different blower driver circuit which pulsed the gnd rather than the +12 feed to the blower, so you can't share a ground on the HMv4.0. I also wanted my older HMv4.0 to be able to share the same CAT5 wiring as the HM's with the new blower circuit (HMv4.1 and up) so I modified my blower driver circuit on the HMv4.0 to run the new blower driver instead. Here is a thread where I detailed what I had to do to make them compatible....
Hopefully you will be able to get your old HM going again, as for the rPi.... that might be dead if it is heating up and not booting at this point....
 
Thanks Ralph, Now that you mention it I remember the discussion but it was certainly over my head. Just might study that thread and resurrect the 4.0 board with your mods. Should make for a fun winter project. Thanks again. Dan
 
Just plugged another rPi in and the HM4.0 came back to life. Looks like I just burned up the rPi. That will save a lot of trouble.
 

 

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