A while back I picked up a Roland VS1680. Now I've always been fond of those big old hard disk recorders, dedicated DAWs in a box, but particularly the VS1680 because it was the first of those I'd ever used. It belonged to a friend of mine who I shared a flat with, and although my old mate Gav is no longer with us and his VS1680 sold off for charity long ago, I always fancied getting one for a bit of a play.

Sadly it arrived in a slightly sorry state because it wasn't packed very well. FIXME I figured I could get new buttons, possibly by ordering them from Roland, but I haven't got round to it yet. A more pressing problem was the lack of any kind of audio from the headphone socket.

Well, gentle reader, what could I do put take all the screws out and have a look? It turns out the service manual is available online, and the headphone amp is a dual power opamp fed through its own volume control off the monitor outputs. The monitor outputs were just fine so the digital side was clearly okay, and that also ruled out the drive for the muting circuit.

Looking at the inputs of IC321 on pins 3 and 5, I could see plenty audio that went up and down when I turned the headphone volume control, so it was clearly reaching the chip. So! It's got to be the chip, right? The outputs on pins 1 and 7 were stuck at -15V so clearly all was not well.

It was an easy enough job to pick the chip off the top of the board FIXME without too much dismantling. I cut away the legs of the chip with a scalpel, lifted the chip off, cleaned up the pads with flux and solder braid, and then soldered down the new chip, and set it up again to test.

Success? Well kind of. Now the left channel worked, but the right didn't. Plugging a bare 1/4" jack into the headphone socket and measuring continuity showed 22Ω from the tip to pin 1, but open circuit from ring to pin 7. Okay, well, nothing for it, all the screws have to come out and the mainboard needs pulled.

It seems that whatever had killed IC321 had also considerably distressed R534 FIXME. The bits left over were spattered onto the steel chassis [FIXME], actually enough to melt the edge of the pressed steel panel a little. I have no idea what could have done this but it's remarkable that it didn't do any other apparent damage!

As an aside, I thought it was pretty strange that the Zobel networks C502/R527 and C505/R533 were simply not present and the pads have never been soldered. I guess they found they didn't need them. Perhaps the opamps they chose are stable enough at HF without it.

FIXME record something on the VS1680 for this post