Weak 12V from PSU

[SmokeMonster]

While I was installing a power XLR to connect up with my CPS1/2/MVS supergun today, I also added voltmeters and three 12V LEDs (a power light and two blue 3-LED strips inside) to my Happ Power Pro, which results in the 12V line dropping to 10.4V.

The Happ has 8A 12V output and it doesn't seem like a few LEDs should affect it so greatly. Any ideas why they're pulling so much juice? It's easy enough to replace them with 5V LEDs though, so I'm just leaving them disconnected for now.

 

[SmokeMonster]

Update: It's actually the Happ's 12V fan that is sucking the voltage from 11.5 (without it) down to 10.4V. I had the LEDs on the same line as the fan, which is why I originally suspected they were the cause.

With all LEDs disconnected and just the fan on 12V, the voltage still reads 10.4V. Is this a problem or should I disconnect the fan altogether?

 

[Mr T Guru]

is it a new power supply?
low voltage usually means the caps are getting old/dry
the power supply should be regulated so as long as the load is less than 8A it'll always output correct voltage.
if it is old replace all of the electrolytic capacitors.

 

[SmokeMonster]

It's about a year old, but barely used. I finally fixed it by adding a fan speed controller. After turning the fan down, it now sits at 11.8V. I will also probably replace the caps eventually as you suggest.

I almost wonder if it's set to not kick 12V to full power until a certain draw is met. For example, it says on the label that 5V requires 1A draw before its voltage should be measured.

 

[jassin000]

Often times with Suzo Happ you'll find a small adjustment pot on the power supply PCB.
Mine is very sensitive, just a small turn will send the power values skyward quickly.

This is the version I'm using... Suzo Happ Power Pro 130Watt

P.S. Nice to see you around SM, we've spoke a few times on TIZ in the past.

 

[SmokeMonster]

Great to see you too Jassin!

Yes, I was a disappointed to find that mine has no independent 12V adjustment inside. Even my cheap old SC200 has that option. Increasing 5V also increases 12V though on the Happ, so I can run 5V a bit high and get both in the range of where I need them.

Now that I installed voltmeters though, it's a constant reminder that the values aren't exactly 5V/12V--frustrating!

 

[SmokeMonster]

I finally got the extra XLR plug for my power cable to connect the PSU to my supergun, and low and behold, the 12V line jumped up 1V when I powered up an MVS. That allowed me to lower 5V to exactly 5V (at the arcade board) and 12V is sitting at 11.8V. Perfect!