Issue: Fan doenst spin

[Patrick Eggel]

Hi community,

after some issues i was able to finish my heatermeter. At the beginning it thought everything works as intended, the HM display went on, i was able to configure everything but after some testing i have the following problem.
The fan doesnt spin when i connect it to ground + blow. (it spins when i use the 5V or 12v at the power input, so the fan is functional).

The HM was in manual mode at 100% all the time and i changed the fan from voltage to pulse mode.

I did some furhter testing, the last point where i m able to get 12V is the left leg of the mosfet. If i connect the fan to the middle leg, the fan wont move. (see next post for better informations)
I would be pretty happy if someone could help me, i dont know much about smc soldering or electronics, this was my first project.
I could do further tests with a mulitmeter if you give me advices how to do it. (i know how to use a multimeter, but i dont have a clue where to use it )



Sometimes i have a second problem. After i start the heatermeter it jump through the menu, it looks like someone would click on all buttons at the same time. Some ideas?

Thank you and greetings from germany.

[Patrick Eggel]

Hey,
i have a multimeter now and i had time to do some measurments. I think the problem is located between the mosfet and the BS170 (Q1)

I marked all values in the picture.

I measured the values when the HM was set to 100%. I tried it also with 0%, i had still 12.15 Volt at the BS170 top output and about 0 V at the bottom input coming from the controller... so the controller seems to work but i get to much V on the BS170->Mosfet

[RalphTrimble]

Upper right pin on that BS170 should be gnd, not 4.7V, start checking for shorts there...

[Gary V]

I had that problem when I finished assembly. It worked on the bench, but after assembling into case, I started having strange display issues and not fan. What happened was when assembling I was not careful and Q1 got stretched and a lead broke and a couple shorted. Check Q1. How I fixed this was to replace Q1 and offset it slightly up toward the center of the pc board and dropped it closed to the pc board. When assembling I took extra care not to contact Q1 with case. There is not a lot of clearance at that point when mounting in case

[Patrick Eggel]

Great, thank you very much, the GND of the BS170 was the problem.... after that i improved about 20 soldering points... it is a long time ago that i had to solder something and some points were terrible.

One short question: Does the heatemeter control the air output only with fan on(12.15V)/off(0V) and the servo for everything else?

[Steve_M]

The HM can control the fan from 0% through 100% as well as the servo from fully closed to fully open. You can modify how the 2 work with each other as well.

Have a look here.