Hairball 1167 rev D - Building The Power Supply - 45V IN PLACE OF 30V

Hi,

I've built the Power Supply in about 4 hours, soldered clean and with care

When I want to measure the R87 with the beginning of the pcb, I measure 45V in place of 30V (CR6 measures -9,7, which is ok!)

Does this has something to do with my Rectifier, where a capacitor isn't working? (noted that I have the right transformator)

I triple tested all my components before and after soldering and everything worked perfectly...

Can someone please help me, I'm pulling my hair out for 48 hours now...  :-[


THANKS!

Sounds like your regulator might be backwards?

Hi,

I think the regulator is at its place...

When a put in the adaptor, the R89 (220R) melted!

What should I do?

THANKS!

PHOTO ATTACHED

deejaywhite said:

When I want to measure the R87 with the beginning of the pcb, I measure 45V in place of 30V

Click to expand...

45V DC in respect to 0V reference voltage ? (make sure, your multimeters battery isn't low)
If yes, this is exceeding the 40V abs.max. rating of a 7824, so expect (at least) the voltage regulator to be broken.
Reason might be your maybe false assumption that you 'have the right transformator' (that would have an order-ID or some transformer specifications, so we're talking about the same subject), that might not be the right transformer or it is hooked up incorrect for real.
Maybe start by updating your profile with your location data, so we get an idea of your local mains voltages.

Hi,

At first, Thanks for everything!
I updated my profile at groupDIY...

I ordered the hairball complete rev d kit, so the transformator was in the kit!

One thing I noticed was the fact that there was something written on the transformator box: 25V 30VA transformator was unavailable, this 30V 30VA will work the exact same in the FET circuit.

So I measured and it was ok, a 34V on the transformator (understanding that this is ok when you have a 10% spare voltage)

I ordered a new voltage regulator and I will solder it onto the PCB, could this be the main problem because my voltage is 15VDC too high and this regulator is 15V?

THANKS!!!!
APPRECIATION!!!
HERO-NESS!!

deejaywhite said:

..this 30V 30VA will work the exact same in the FET circuit.
So I measured and it was ok, a 34V on the transformator (understanding that this is ok when you have a 10% spare voltage)

Click to expand...

About 13% transformer regulation for your unloaded transformer.
This 34VAC is about 34V*SQRT(2)-2*0.7=46.7VDCpk after rectification. At rated load and nominal AC mains, this will drop to about 41VDCpk.
The resistors R87 and R89 set the 7824 voltage regulator for 24V*(1+220R/1100R)+0,008A*220R=30.56VDC (+/-parts tolerances).
The 1K1 resistor R87 will transfer 24V^2/1100R=0.523W to heat, so the 1W rating is sufficient.
The 220R resistor R89 will transfer 6.56V^2/220R=0.195W to heat, so use a 0.5W rated part (an only 1/4W rated part will be hot).
Your maybe broken (melted?) 220R resistor might had to dissipate more than it could take, so replace with sufficiently rated part.
To make it (hopefully) work with your dual 30VAC or 60VAC center tapped secondary transformer you will need a load connected in order to get the too high transformer secondary voltage down. This will either be your compressor circuit or a temporary about 240R/5W resistor connected between 30V and 0V for an assumed 125mA load.

I ordered a new voltage regulator and I will solder it onto the PCB, could this be the main problem because my voltage is 15VDC too high and this regulator is 15V?

Click to expand...

You want a 24V fixed voltage regulator (LM7824, uA7824,...), not a 15V regulator for this circuit and pcb layout and for the increased regulators input voltage, causing higher dissipation, this vreg will need a heatsink attached.

Definitely shouldn't have melted.  We tested the 30V in all of are circuits with no issue.

As always thank you for the lesson (and math!) Harpo.

I've just seen the 45V issue with a backwards regulator.