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Roland TR707 Repair
Roland TR707 Repair – This unit was completely dead but otherwise in pretty good condition.
The first thing to check was the usual power supply suspects. The fuseable resistor was fine, the 5V regulator was fine and the -10V rail was also good. The power jack was fine. We did notice that the supplied adjustable ‘wall wort’ was outputting 20V when set to 12V and after further testing discovered that when set to 7.5V it output just over 12V which was ok for the unit.
The fact that these were all good….was not good news.
After some diagnostics involving the boot up reset circuits etc we managed to get signs of life. However, there were a number of the buttons not working (STOP being one of them), ACCENT was not working and several voices were not sounding. Pattern play worked but Track play did nothing. It would also not boot up into test mode either.
More diagnostics and head scratching, swapping over some logic ICs after sockets were installed, buttons cleaned, membrane cleaned, diodes tested and eventually she started behaving properly and test mode was achieved.
Thinking she was then finished there was an issue with no Hihats.
This was down to the roland capacitor adhesive turning corrosive and eating away trace/component legs and a jumper wire.
Once this was sorted and the faders cleaned the factory patches were loaded in and voila she lives.
