servo/fan problems in RD3


 
I've had this blower out there for several years now and haven't had issues. This is my second blower becuase originally the HM used a 60mm blower, which I had designed the original RD around. I made a RD3 around that blower and it was just too big, so I found the 50mm blower with the same specs and built around that, later Bryan changed to the 50mm blower because it was more widely available and smaller (with the same specs). Still, I'd have to say this blower has been outside in the elements for about 3 years now with no issues.
The whole reason I went through the trouble to work out sending the probes over the CAT5 cable was so I can keep the HM inside but still connected to the RD3. It will operate well with up to about 50ft of cable, anything more than that the servo tends to flake out. I've only replaced the ends on the CAT5 cable about 2 times over 3-4 years, which also surprised me. I'm not even using outdoor cable, or any kind of sealed connectors, just regular cheap CAT5 cable and crimp on ends.
 
Hey all I hate to revive this thread but I'm having power problems again with my RD3 plugged in. I thought all was well after last time except that I did something probably dumb. Instead of going to home depot to buy an ethernet jack that the RD3 was designed for, I used one I had on hand that didn't actually fit the RD3 assembly. As such, I left the thing dangling out of the case. And this probably caused me more problems because eventually I started having a problem that when I went to start a cook with my Heatermeter, I'd hook everything up and then plug the power in and the display would flash on and off and each time the servo would jerk forward a little bit.

I thought maybe the capacitor I had put inline had gone bad outside in the elements. I pulled it out and was still having the same problem. I went to home depot and got the proper cat5 jack and it seemed to work until I put it all back together and tried a cook. Back to power cycling. Tonight I took it apart again to play with it and I replaced my servo with a new one. Same problem. I noticed that even with the servo motor removed from the RD3 CAT5 jack, I was getting this power on and off response. So I suspected something was up with my fan. I pulled its wires out and reconnected them. Things seemed better so I put it all back together and did a couple of test power up and down and open and close of the lid. All seemed good until I was putting my tools away and calling it quits. I decided to test it one more time, and son of a ____ if it didn't do the power cycle thing again.

Any guesses what could cause this? It seems like a short of some kind possibly. Could my blower have somehow gone bad and caused this? Is it more likely I have something crossed somewhere else? Youtube link below is a video showing what it looks like when power cycling like I mention.

https://www.youtube.com/watch?v=sDfjeWWSgkI
 
You either have a short somewhere in your wiring or your power supply is browning out from the current draw. It is common for a power supply to work fine with just the fan but brown out when the servo moves, particularly the 1A power supply that is recommended with for the HM. I had suggested that the standard HM PS change to 2A but Bryan did some very technical analysis that apparently proved 1A is sufficient. However, in the real world I see 1A supplies brown out all the time from the load so IDK what else to say...

You might try powering up the HM without the RD3 plugged in, set the output to 0% so there is no power draw from the servo and fan, then plug in the RD3 and see if it power cycles. If it stays solid until you make the output go up then it is likely your power supply browning out, if it power cycles even when at 0% output you probably have a short somewhere.

Easiest thing to do is try another power supply. I know I have a bunch of them around the house for various devices like answering machines, cordless phones etc... 12VDC tip positive with this connector is a very common power supply....
 
Thanks Ralph. I have been swapping power supplies and was using the highest amp output 12v supply I could find around my house. It was 1.5amp output. But I just so happened to notice the power supply for my wife's breast pump is 12v 2amp. So I grabbed that and it works as expected. When I go back to the 1.5amp supply it cuts in and out again.

So yeah, I think I agree with you, 2 amps seems necessary if you are running a servo and fan. Now I just have to fight my wife for this power supply for a few months :)

//edit actually I found a power supply for an old apple time machine that is 12v 1.8amp. It seems to work well too.
 
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I figured it was the PS... not all Amps are created equal from my real world experience... You may find a 1A PS that works fine with your rig, and a 1.5A that browns out. I find the old school transformer type wall warts to be more true to their specs than the new fangled switching units. Perhaps the modern IC controlled power supplies have current sensing circuits that flake out on the initial draw that older discreet power supplies just ignore..

I am also assuming that the servo's, blowers, rPi's etc may differ a bit in current draw from unit to unit, so Bryans testing may have proven 1A is enough for the parts he was holding but it may not be enough for a different mix of parts.

At any rate, an extra amp or two does not cost much $$ at all when buying a 12V PS, so I always suggest buying at least a 2A unit.
 
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