This is my first post on this forum. I know this section is about building and I am requesting assistance in regard to a repair. I hope it will be allowed for consideration. I would think that the same expertise that applies to building a pedal would apply to repair. If not I apologize. My problem is as follows:
I found an old MIJ Boss HM-2 that doesn't work for almost nothing and I want to try to fix it.
1. A sticker on the back says to use a Boss "ACA" adaptor only. I read online that if you daisy chain it with another Boss pedal the "PSA" adaptor will work.
2. I daisy chained it and it doesn't work.
3. When you daisy chain it, the PSA adapter light starts flashing.
4. The red LED on the HM-2 does not light up.
5. When you put a 9 volt battery in it, the battery gets hot.
6. When you connect it to the guitar and amp, the guitar signal does not go through the pedal.
7. I opened it up and there is nothing obvious, i.e., no broken wires; no caps, resistors or other components that look defective or broken solely by visual inspection.
8. VOM test shows there is power where the red and black wires connect to the PCB. The power was obtained from a Duofone AC adapter with output DC 9v 300ma.
Does anyone have any suggestions on how to fix? Suggestions on caps, resistors that may be replaced to make it work? Why does the battery get hot?
I am going to try to post a schematic I found online. I hope that is allowed. Thanks in advance for any help with this problem
(Couldn't figure out how to attach the image)