Do you have a Volt meter to test that there is at least the proper
voltage coming out from the adaptor? It would be best to test it while
it is connected to the drum machine, so that it is properly loaded. A
no load test may not indicate its true performance.

If the adaptor is working, then check for any opened connections such as
bad contacts, connector(s), and etc in the electrical path from the
adaptor in to the drum machine.

The next step would be to troubleshoot the electronics of the devices in
question, which is something that cannot be done over an email. At this
point, you will have to give it out, unless you are trained, tooled up,
and experienced at this sort of work.

--

Jerry G.
======

"Kevin Ross" wrote in message
...
I have a device (a Roland TR-505 drum machine) that works only on
batteries. When I insert the AC adapter (the original, which obviously
worked at one time) the device shuts down. The AC adapter appears to be
converting the correct voltage at the plug. I don't know much about
testing circuit boards. Any ideas as to why this pattern is occurring?
Any leads on what I might do to figure out how to repair device without
spending a lot of money. It's an old device but it does it's job well
and suits my needs when it is working correctly.