Casio FZ Samplers

Hello all,

Looking for advice from FZ-10M (-20M, HS-1/E) owners, or the FZ-1 as that might also be applicable.

I bought an FZ-10M that needs repair: specifically, it does not start, only showing a screen light and (sometimes) 2 red LEDs.

I have little in the way of diagnostic equipment but am happy to try if I get plausible suggestions. The service manual for the FZ-1 only describes the diagnostic program IF it loads in the first place, but I don't even seem to get that far!

I doubt it's just the (infamous) LCD screen, but to check, how would I go about testing buttons or sound, without being able to see what the screen says? Anything simple that will produce a sound or change some LEDs if the whole thing isn't busted is what I need.

Otherwise, hopefully someone knows the described pattern of failure, and can suggest what needs replaced, tested, etc.

Thanks in advance. I really hope I can get this fixed and get those filters blasting!

DB

Found a busted +12 V supply to the FDD and suspect it indicates a greater underlying issue on the PSU. Full details here - http://www.vintagesynth.com/forum/viewtopic.php?f=5&t=78014&p=740163#p740163 - and would appreciate any opinions/educated suggestions from anyone who actually knows how power works ;-)

Thanks

Hey Fran, thanks for the reply! Some very interesting advice there. I will definitely incorporate that into my tests.

I only have a voltmeter, not an oscilloscope, so I'm not sure whether it will handle AC. But probing relevant DC points will hopefully be informative enough.

Thanks again, and I'll let you know what I discover.

Fran,

Voltage across the +12 V capacitor is the same as at the FDD: -0.15 V instead of what it should be… Where do I look next? Haha. Power supplies almost completely baffle me, although I’m very keen to learn.

With power off, and my voltmeter in resistance mode at the "20 k" setting, the reading across + and - of the rectifier is about 0.69 regardless of the polarity that I apply the probes.

Back to the schematic... Any other quick things to check would be superb, if they can narrow down the problem. Getting a new fuse is a good idea in any case, but I'm not sure I can reach the shops in time today...

Thanks again
Dan

quoting my subsquent posts from elsewhere:

[…]

Yeah, checking voltages so far, I still have only one thing missing:
http://i.imgur.com/NRkYXXC.pngBut I doubt that FD +12 V can be holding up the rest of the system; I managed to get the FDD to make disgruntled noises by feeding it power hijacked from a PC, and the FZ didn’t care either way.

Nonetheless, I’d like to ‘walk back’ from that cap (with the voltmeter) to determine whether anything more serious/early than an electrolytic is broken here. Does this sound plausible, and if so, would you be able to suggest what/how to probe? Thanks.

Also, very good point about the RES line [CPU/system reset, active low]; I’ll check that next. It does seem to trace back to the S1WBA10 rectifier that also sources the failed +12 V… :-O

[…]

intriguing: CPU RES line seems to hover around 0.12 V, whereas being active low, I assume it is meant to bounce up to +5 V a few seconds after power-on.

Next thing is to test the hell out of that S1W rectifier – because both the missing +12 V FD power and /RES signals eventually trace back to there. For someone who, as is obvious, is very new to these sorts of diagnostics and circuits… how would I go about testing a rectifier? Datasheet first, of course… off to Google I go.

[…]

Basically, what sort of DC should I expect to find if the rectifier is working properly? Testing with power on will have to wait till I get someone to operate the button for me, as its location is too close to some huge caps and whatnot for my liking, to do it on my own.

Thanks again. Think this might be getting somewhere...!

I might have traced the lack of +12 V to the voltage regulator in that line. I say “might” because I sometimes got readings from it on my voltmeter, sometimes not at all. This might have been purely because it is so flipping hard to reach with the probes. It must finally have shorted as I saw a nice big white spark between its legs (ooh-er, missus), and then it was gone. That short seems to have cascaded backwards (is that even possible?) because now I have a blown fuse F4, which serves the aforementioned rectifier S1WBA10. So, now I have no +12 V or /RES! However, I seem to recall /RES was back to running properly at +5 V some time before the fuse blew… I don’t know; it’s all blurring together.

As you can see, I need to stop this for a while and have a sleep. On the plus side, I didn’t die. I guess? That’s probably a good thing.

/RES is/was presumably the real issue here; credit to acreil at GS for noticing that as it might have taken me ages to realise. So, the next steps are to replace that fuse, hang some wires off that vreg to test it safely… and learn the dark art of transistors, I suppose.

I replaced several electrolytic capacitors while I was at it, which might improve my odds once the fuse is repaired, but me tell you: the PSU was not made for easy servicing, as without cutting some of the main wires, you can only balance it on its side (via the heatsink) and sort of poke at it horizontally with the soldering iron. The same applies to the main board, by the way, which just has to chill on its side at the back of the chassis.