Hello guys,
I m actually trying to repair an old delay unit D1500 from Yamaha. The psu gives the right voltages but the front panel was not responsive, no output and screen showing 7777. I found a broken track just under the RAM IC M5M5118p. I was probing pins when at pin 18 CHIP select input S2/, i could hear my injected sine wave but no effect, this pin 18 is supposed to be connected to the front side of the pcb with a metalized vias, this one is located under the M5M51118p and it was broken !.... I made the connection back but it's far from being fixed now. Right part of the front panel is responding now, from "RATE, TIME,... to MIX, INV", leds turn on when switch button is pushed. Rate is also reacting by using increment or decrement switch...
I might have other broken tracks so im digging it out.
Leds screen does not show 7 777 anymore but it's totally silent now, not showing anything. Vu meter led is working. I have no delay out nor mix signal ouput.
One strange thing is i cannot set the clock adjusting pot V104 as as soon as i reach approx 200khz it falls to 5khz... so i cannot reach the 512khz which is mandatory page 3 of the service manual.
I m afraid the ROM ic is bad. What you reckon ? Cheers !
I m actually trying to repair an old delay unit D1500 from Yamaha. The psu gives the right voltages but the front panel was not responsive, no output and screen showing 7777. I found a broken track just under the RAM IC M5M5118p. I was probing pins when at pin 18 CHIP select input S2/, i could hear my injected sine wave but no effect, this pin 18 is supposed to be connected to the front side of the pcb with a metalized vias, this one is located under the M5M51118p and it was broken !.... I made the connection back but it's far from being fixed now. Right part of the front panel is responding now, from "RATE, TIME,... to MIX, INV", leds turn on when switch button is pushed. Rate is also reacting by using increment or decrement switch...
I might have other broken tracks so im digging it out.
Leds screen does not show 7 777 anymore but it's totally silent now, not showing anything. Vu meter led is working. I have no delay out nor mix signal ouput.
One strange thing is i cannot set the clock adjusting pot V104 as as soon as i reach approx 200khz it falls to 5khz... so i cannot reach the 512khz which is mandatory page 3 of the service manual.
I m afraid the ROM ic is bad. What you reckon ? Cheers !
Statistics: Posted by debidoo — Tue Jul 16, 2024 8:10 pm