Heavy Metal 2 PSU problem

[Crawf]

Hi,I picked up a Japanese built HM-2 from e-bay very cheaply and considering the age of the pedal its in top condition, on trying it out with a battery it plays perfectly but when hooked up to my Boss BCB 60 PSU it sounds gated as if something it misbiased so i was wondering if something could have been damaged in its life which would still allow it to work OK with the battery  but not the power supply, I'm afraid I'm not knowledgeable enough although "protection diode" came to mind but maybe someone can offer other explanations, cheers Crawf.

Here is a link to the schematic  http://www.freeinfosociety.com/electronics/schemview.php?id=134

[petemoore]

  If it 'likes' 9vdc from batteries, a power supply can probably supply ripple-free enough DC for it to like that too.
  I would check for reverse polarity, actual DC voltage of PS, and PS when connected to circuit, what voltage the circuit actually 'sees' [test voltage on active pins etc...stuff like that.
  As far as 'damage'...I don't think so, if it's happy with batteries, it should be able to be made to be happy with a PS...maybe the PS is 'funny' or something happens when it's plugged into the disorter...

[liquidshadow]

I think you could find the answer here http://www.stinkfoot.se/andreas/diy/articles/bossadapt.htm

[Crawf]

Thanks Liquidshadow and Petemoore ,Exactly right, it will work with a battery but not with a power supply on its own but in my board daisy chained from other pedals its fine which reminded me i had CE-3 chorus that did the same thing  :icon_redface:thnaks again Crawf.

[O]

Read the link Liquidshadow posted. You're going to need an ACA adapter instead of the PSA (newer) boss adapter. I have a couple of those pedals and they want an unregulated power adapter to work right.

[Crawf]

I did read it and explained what i had read was what was happening with my pedal, it runs fine when in my board and daisy chained from other pedals, from the link:-

When powering a Boss ACA (old-style) pedal from a 9v PSA adapter, the LED barely lights up. This is normal and expected behaviour, since the 9 volts fed to the pedal really is too little - it wants 12 volts, remember? But when the power is being provided via a daisy-chain, with other PSA pedals in the chain, the LED suddenly lights up as normal... I investigated the issue, and sure enough, my CE-2 didn't want to work with the PSA adapter alone. When I added a daisy chain and connected a Blues Driver to it, there was no change - the CE-2's LED still wouldn't light up. But when I added a signal cable between the pedals, the thing shone as bright as ever! What happens is that all the pedals in the daisy chain share a common ground, which bypasses the voltage limiting components in the ACA pedal(s), causing the CE-2 (in this case) to receive the full 9 volts.

thats whats happening to my HM-2, it works so i'm happy, cheers Crawf.