Re: Dead DX7 Mark I - Repair questions -- Help!

Got a multi meter?First: make sure the power supply is working. ALWAYS. Trouble-shooting 101!!!!There will be +5VDC, +12VDC and -12VDC.on the PS output connectors.Plus the battery +3.0VDC on the main board.. Measure from chassis ground if you can't find the specific ground pins. Chassis will be common to all. Measure them with both the DC section of the meter first and the AC part selected later. The DC voltages only need to be close. If a tiny bit high or low, probably OK. Measure the AC component of each DC voltage. It should be very near 0.0 VAC. Sometimes the meter will help determine if the filter caps are pooched. This is very common. Power off for the next part.Visually inspect them. If the tops or bottoms are swollen or rounded up replace all of the caps in question. Or if you see black goo around the bottom that is not glue. Usually it's the big guys that will go. Select caps that are both higher value capacitance, ie 3000uf instead of 2700uf and 35V 0r 50V caps where 25V were used. They will then live longer than you will. You can scale up by 2X for both values and improve the supply. The only limitation is available space and the lead spacing- they must match. Oh by the way, you should probably be handy with a soldering pencil, and know how to remove components without fucking up the circuit board's traces and through-holes. Those springy push button solder suckers are death, as they can cause tip shift that damages the pads. Solder wick is less violent.Now someone else can instruct on troubleshooting those bloody E! boards. I usually return the DX7 to stock condition while troubleshooting and then go back and reinstall the E! hardware. Loading back the sounds files is always confusing with E!Happy troubleshooting, If the battery is pooched, replace and reload patches. I use 3.6VDC backup batteries- they live longer and don't exceed any RAM chips maximums.Gregg