MOTM

Hey all!

Here's one for the troubleshooting crowd - my power supply is doing a 
*funny* thing.  Back when module #38 was installed, I switched on the 
power and only the red LED's lit and stayed on solid-no modulation 
from the LFO's, etc.  Naturally, I switched the supply off!  When I 
got the courage to power it up again, all was well.  Or so I 
thought...

Yesterday I installed module #44.  A new distribution board was added 
and the wiring was rearanged to tidy up.  I powered up and this time 
the green LED's lit solid.  I turned it off and then back on.  Now 
the red LED's lit solid!  I left it like this to confirm what I 
thought was happening.  Checking the voltages at my DC terminals on 
the supply, I found a solid -15vdc and only +.71vdc.  When the green 
LED's lit solid, the opposite was true- solid positive voltage and 
only -.71vdc from the supply.

When the supply powers up normally, all works well.  The voltages at 
any module show no sign of brownout.  With no load, the supply always 
powers up correctly.  I haven't pulled one supply at a time to find 
an offending module, because the odds are against any one module 
shorting one-or-the-other half of the supply.  That is next on the 
agenda, however.  The supply is a Power One HBB-15 which according to 
many, *should* handle 45-50 modules.  A star wiring pattern has been 
maintained, and the three distribution boards are MOTM-960's. The DC 
wiring is 12-guage stranded from the supply to the first terminal and 
12-guage to each distribution board.

What do you think?  My guess is the power supply goes into short 
protection during inrush.  The .71 vdc would be a normal forward 
voltage drop from the pass transistor, showing up in parallel at the 
shut-down side of the supply.  Anyone else, have something like this 
happen as they neared the limits of power?  Am I just going to pop 
for the next bigger (or greater!) supply?  

I summon the vast power of knowledge that is the MOTM Group!

Chub - half-powered!

ps-Paul should really go into cartooning!