Hi,
I had a similar problem with mine, also had been in storage for many years...
On mine I found that the power jack had broken, all was working when it had put in the cupboard years back with my MC-202 etc.
The pin centre pin on the 707 had literally just gone don't know how or why. I found a simple conversion to run the unit from batteries
on the net and everything worked once on battery power, then just needed to clean up and move the sliders to get rid of the scratchy pots.
You can still get replacement power jacks direct from Roland mine cost £3 or £4 I know they're a common point of failure on the 707.
Good luck with yours
Cheers Cliff
To: tr-707@yahoogroups.com
From: drevelynalicea@...
Date: Mon, 7 Mar 2011 21:04:37 +0000
Subject: [tr-707] repair
hi
new to the group. need advice. my tr707 has been stored away for many
years. tried to use it recently and won' t work. Lights do not go on.any
idea what could be the problem