Those stickers were in very widespread use (maybe still are?), mainly for inspection - the inspector saying "here's the fault I've spotted" so when someone comes to repair it later they can find the problem. Also sometimes used when applying a documented mod - to first identify all the places where cuts/wire-adds were needed to avoid mistakes when then getting on with the work.
So the sticker doesn't give any clue who did this, but plainly they did so very deliberately.
Shorting C59 seems a very odd thing to do - C59 is providing AC coupling (ie. removing any DC offset) from the analogue filters around the first two opamps before feeding into the squarer circuit that turns it into a digital level to feed the SERPROC. I can't think of any reason for wanting to remove that - it will give poorer performance in normal use, and if you were wanting to (say) feed the circuit from an external circuit that aims to do a better job than this one, you'd want to bypass the first two stages not just this one point. I can imagine people using the cassette circuit for things other than cassette (amateur radio?) and wanting to modify it to suit, but this particular mod doesn't seem to make sense.
Are you absolutely sure this is shorting C59 rather than a repair of a broken track leading to C59? Or maybe it was meant to be that, and they botched the job (despite having stickered it in advance!).
So the sticker doesn't give any clue who did this, but plainly they did so very deliberately.
Shorting C59 seems a very odd thing to do - C59 is providing AC coupling (ie. removing any DC offset) from the analogue filters around the first two opamps before feeding into the squarer circuit that turns it into a digital level to feed the SERPROC. I can't think of any reason for wanting to remove that - it will give poorer performance in normal use, and if you were wanting to (say) feed the circuit from an external circuit that aims to do a better job than this one, you'd want to bypass the first two stages not just this one point. I can imagine people using the cassette circuit for things other than cassette (amateur radio?) and wanting to modify it to suit, but this particular mod doesn't seem to make sense.
Are you absolutely sure this is shorting C59 rather than a repair of a broken track leading to C59? Or maybe it was meant to be that, and they botched the job (despite having stickered it in advance!).
Statistics: Posted by arg — Sat Nov 30, 2024 9:47 am