issues adding new RD3 to existing HM 4.2


 

MarinoV

New member
Hi all,

I've been enjoying a Heatermeter 4.2 on a Zero Pi W since last fall. I'm now trying to add a RD3 to the mix (hard-wired - no RDTC board), but I'm having some trouble. My forum searching has not yet turned up the 'dummies guide' I clearly need...

The issue is that I get no response from the fan (Delta BFB0512VHD) nor the servo (Towerpro MG90S). I've tried setting the temp setpoint at 225 and -100 - in both cases the fan did not turn on at all. The grill/ambient temp was around 67, so I would expect a 225 setpoint to push the blower into afterburner mode.

RD3 RJ45 jack has been wired per https://github.com/CapnBry/HeaterMeter/wiki/Blower-and-Servo-Wiring:
  • The servo has 3 wires: red (punched to RJ45 pin 3), orange (punched to RJ45 pin 6), and brown (capped off)
  • The fan also has 3 wires: black (punched to RJ45 pin 4), red (punched to RJ45 pin 5), and blue (capped off)
I've tried re-punching the wires on the RD3 RJ45 jack, and have tested the CAT5 cable on my PC. Any suggestions on what to check next? Can I look for any indicators in the HM logs that might explain my issue?

I should mention that I'm powering the HM 4.2 through the Pi Zero W - no 12v brick here. Is that power adapter required to support a blower/servo?

Thanks,
Marino
 
Yes, 12V power is required to run the blower at all so good catch there. The circuit only steps down the voltage from 12V to get the blower to the right speed, it does not step up the Pi's voltage.

The servo isn't working because the ground wire (brown) also needs to be punched down to ground (pin 4 of the RJ45) as well. That can run off the 5V from the Pi as long as the power supply is powerful enough. If it isn't it will just brown out the Pi and reboot everything so no real damage, but it won't function properly if the 5V supply can't supply the current.
 
Update: blower is now working. The servo, however, is jittering like a nun in a brothel. I saw Bryan mention in another thread (https://tvwbb.com/showthread.php?76888-Servo-troubleshoot) about this potentially being a capacitor issue. I double-checked the solders on all four of them, and re-did ones that were lacking. However the jittering persists. Any suggestions?

This may be unrelated, but I'm having an issue with the LCD display as well. The backlight turns on but I get nothing on-screen - no characters, no numbers, just a white backlit screen. I'm not too concerned about fixing that (I love me the web interface), but I'll mention it just in case that lends a clue to some components being the cause of my servo jittering.


Edit: after posting the above reply, I tinkered further and was able to resolve my problem. The servo no longer jitters - it now smoothly opens to appropriate intake levels depending on fan speed.

My issue was the 10" network cable from HM to RD3. For S&G's I tried a 3' one instead - this alone fixed my problem. The servo worked as expected on my next bootup.

The 10' cable worked on my PC, so I suspect the issue was either a) attenuation or b) I did a poor solder on the HM RJ45 jack.
 
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The capacitor mentioned would go on the far side of the cable, closest to the blower, so you might be able to use the 10' cable if you add a new capacitor down there.

I'm not sure what's going on with the LCDs, I know Gary V reported a similar issue, but I've just updated my PiB 4.2, and a ZeroW 4.3 and both were uneventful in that it came right up on the reboot. I did make the mistake of flashing a Pi3B+ with the ZeroW firmware so I had to get my dang screwdriver out to flash it properly, but it also came up once I put the right firmware on it. I'm not sure what could cause the LCDs to stop working so if anyone has more information I'd be enjoy becoming more informed.
 

 

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