Hi all,
Just finished my 1.02 build and having a strange set of problems. My troubleshooting skills are somewhat lacking so Im hoping for a little direction. Ive double checked all the components and IC orientations and after correcting a flipped diode and electro cap, everything seems to be good.
When not plugged in, I get normal voltages from the power suply, +15/+5/-15 but as soon as its plugged into the main board the -15 drops to ~0V. That said, I was able to get 5V at TP1 and the sequencer appears to be functioning normally. Unfortunately there's no audio and the LCD is not powering on(im guessing due to the lack of a true negative rail)
Would the loss of a negative rail imply there's a short somewhere? Or something wrong with an IC? Any pointers on where to start troubleshooting?
No negative rail, no LCD
Update: I reseated the big ICs, reset the connectors and reflowed some sad looking solder points and I'm getting -2.5V on the negative rail at J5. Getting the same measurement at IC64 and IC65 but all the other negative rail check points are at -1.5V
Update, I disconnected the RPs bringing the negative voltage into each section and was able to isolate the problem to the handclap section. I've double checked the orientation of all the ICs and polarized components and used the voltmeter to make sure there's not a short somewhere in the circuit but there's still a negative voltage on the negative rail in the in the HC even though the power is disconnected. Seems very strange.
That said, all the toms, rim and hi-hats work along with the sequencer, though I'm still not seeing anything on the LCD.
The kick sounds really clicky, almost like a cr-78 kick and the snare sounds more like a tom drum so I think there may be something wrong with the noise circuit. I VCO1 on the kick is giving me really short clicks and VCO2 on the snare doesn't seem to be outputting anything at all.
The Ride and Cymbol are both there but really quiet, the ride seems to have some kind of digital noise riding over the whole thing.
I'm on 1.02 boards, mux_sh board disconnected for now with whatever OS comes stock.
That said, all the toms, rim and hi-hats work along with the sequencer, though I'm still not seeing anything on the LCD.
The kick sounds really clicky, almost like a cr-78 kick and the snare sounds more like a tom drum so I think there may be something wrong with the noise circuit. I VCO1 on the kick is giving me really short clicks and VCO2 on the snare doesn't seem to be outputting anything at all.
The Ride and Cymbol are both there but really quiet, the ride seems to have some kind of digital noise riding over the whole thing.
I'm on 1.02 boards, mux_sh board disconnected for now with whatever OS comes stock.