Casio Collectors

Hi.

Does anyone have the schematic pages for the PG-380 midi guitar? I have a dead trigger (after a full recap) for one string. But the scans for the schematic pages are all missing from the PDFs that are available online.

I need to know where the negative lead from C36 on the trigger board (board MA3M) is supposed to connect. I would guess it is supposed to have a lead that connects to ground, but it really does not look like there ever was an actual connection on my board (though, it is possible that the traces were corroded away by leaky capacitor gunk).

I also need to know where the test pads are for the calibration procedure (supposedly indicated on pages 2 and 3 - the missing pages).

Thanks very much - DT

My apologies, I realized that I had the schematics but hadn't uploaded them onto this site.

Just put them up now, hope that helps!

Cheers, Graham

The EPROM should be fine, they're bullet proof. What are you running the synth output into? A guitar amp, mixer etc? The volume level out of the synth/guitar mix socket will be roughly the same as a guitar output level - a fair bit quieter than a normal line level synth.

Have you replaced ALL the capacitors on ALL of the boards (including the big main synth board, not just the rectangle string trigger boards)? Synth sound related issues will relate to the main synth board, if all things are equal and all strings are triggering properly. There is a capacitor on the synth board that I had to replace.

Make sure you replace all of the caps on both trigger boards - people often stop at the uppermost board because it resolved their problem but the second board also affects triggering levels and can contribute to a pseudo distorted sound. Do the lot. I did and it fixed all of the sound and triggering level problems.

Cheers, Graham

Hi Graham,

I replaced all electrolytics on the surface mount boards. I had to - mine were at the point where if I just touched them, they would fall off (made removal quite easy :). The only board I did not do was the midi and PSU board, which is through hole.

I am playing through a guitar amp. The midi sounds are MUCH louder than the guitar sounds, so perhaps I have an issue on that board. Maybe it’s that relay that feeds the mix. But that wouldn’t really explain why a good number of the synth sounds sound the same (unless the distortion is somehow masking the differences).

I don’t really understand what the calibration does - but hopefully that will clear up the last trigger issue.

best,

DT

> On Jun 23, 2015, at 3:42 AM, gmeredith1@... [casiocollectors] <casiocollectors@yahoogroups.com.au> wrote:
> 
> 
> The EPROM should be fine, they're bullet proof. What are you running the synth output into? A guitar amp, mixer etc? The volume level out of the synth/guitar mix socket will be roughly the same as a guitar output level - a fair bit quieter than a normal line level synth.
> 
> 
> 
> Have you replaced ALL the capacitors on ALL of the boards (including the big main synth board, not just the rectangle string trigger boards)? Synth sound related issues will relate to the main synth board, if all things are equal and all strings are triggering properly. There is a capacitor on the synth board that I had to replace.
> 
> 
> 
> Make sure you replace all of the caps on both trigger boards - people often stop at the uppermost board because it resolved their problem but the second board also affects triggering levels and can contribute to a pseudo distorted sound. Do the lot. I did and it fixed all of the sound and triggering level problems.
> 
> 
> 
> Cheers, Graham
> 
> 
>

The synth sounds are generally louder than the guitar but not heaps louder. I suspect there is a component still to be replaced. Many of the onboard sounds do sound boring and the same - which is why people buy the cards to get more varied sounds. Probably even more similar if they're overdriven like yours.

There is a surface mount cap on the big synth board - you'll need to replace this. Also check that you've done both sides of all the boards (I can't remember if there are some on the other side)

One really big problem I had when I did mine was that when I replaced the caps I still had trouble. It ended up being that where the tracks were on the bottom of the board was corroded, and even after thinking that I'd cleaned the tracks before soldering in the new caps, there were bad connections still. I had to redo them. Check each cap leg and track with a multimeter for continuity of the solder joint (should read zero ohms if good). It took me ages to get it right. On some caps I had to connect them not at the track's pad but a bit further up by scratching the coating off the track and soldering it there. It was that bad - although it didn't actually look bad.

Did you use tantalum through hole caps, or original surface mount caps? I used the original surface mount caps - big mistake and a pain in the neck to solder. Use tantalums if you can.

Again, I think you have a bad solder joint somewhere. I had the distortion sound at one point until I redid all my cap joints.

Until you get the level and distortion issue sorted out, you won't be able to calibrate it.

Keep trying and don't give up! You'll get it if you do.

Cheers, Graham

Hey Graham,

OK - well, it's reassuring (sort of) to hear that they are supposed to sound similar (some, like ambulance, sound appropriately crazy).

"There is a surface mount cap on the big synth board “

Ah - do you mean that there is a cap on the other side of the big synth board (MA1M?) I only changed the caps that were on the top side. Please clarify. I was hoping not to have to take that off...

For the record, my guitar did not work until I recapped the top of the synth board. I think in some of the tutorials it states that it will still work - but if the caps are corroded enough and go open then it kills the circuit.

I was pretty careful to scrape off all corrosion. The hardest part was getting melted black plastic from those SMD mounts off. I used a hobby knife to scrape at them until they were clean. And I did test all connections. Everything has continuity where it should have it) and I do get six independent triggers.

But I guess I’ll go through and hit everything again.

I used through hole Nichicon PW electrolytics for all the polarized electrolytic SMD caps. it was quite easy to get them on once I had the pads clean. And there is plenty of room to lay them flat, so the double stacked board wasn’t an issue.

ALSO - it’s nearly impossible for me to see where the test points are for the calibration (meaning the three “adjustments” on the adjustment page in the manual). Would you happen to have a color version of the schematic? Then I could at least see which side of the board the test points were on. I mean.. I can sort of guess, but…

Would have been nice if Casio had labelled the test points on the boards. Oh well…

best,

DT

> On Jun 24, 2015, at 12:48 AM, gmeredith1@... [casiocollectors] <casiocollectors@yahoogroups.com.au> wrote:
> 
> 
> The synth sounds are generally louder than the guitar but not heaps louder. I suspect there is a component still to be replaced. Many of the onboard sounds do sound boring and the same - which is why people buy the cards to get more varied sounds. Probably even more similar if they're overdriven like yours.
> 
> 
> 

> There is a surface mount cap on the big synth board - you'll need to replace this. Also check that you've done both sides of all the boards (I can't remember if there are some on the other side)
> 
> One really big problem I had when I did mine was that when I replaced the caps I still had trouble. It ended up being that where the tracks were on the bottom of the board was corroded, and even after thinking that I'd cleaned the tracks before soldering in the new caps, there were bad connections still. I had to redo them. Check each cap leg and track with a multimeter for continuity of the solder joint (should read zero ohms if good). It took me ages to get it right. On some caps I had to connect them not at the track's pad but a bit further up by scratching the coating off the track and soldering it there. It was that bad - although it didn't actually look bad.
> 

> Did you use tantalum through hole caps, or original surface mount caps? I used the original surface mount caps - big mistake and a pain in the neck to solder. Use tantalums if you can.
> 
> Again, I think you have a bad solder joint somewhere. I had the distortion sound at one point until I redid all my cap joints.
> 

> 
> Until you get the level and distortion issue sorted out, you won't be able to calibrate it.
> 
> 
> 
> Keep trying and don't give up! You'll get it if you do.
> 
> 
> 
> Cheers, Graham
> 
> 
> 
> 
> 
> 
>

Turn up the sensitivity pots for each string. I found that they have to be almost right up maximum to trigger satisfactorily.

Not sure if the pickup can be raised - it think it's at a fixed distance?? It should b about 3 mm from the strings.

Cheers, Graham

Hi Graham,

Thanks very much. Unfortunately, my trimmers are up all the way and the string distance is 3mm. Hm… 

I read one post where a sensitivity issue was on account of the hex being installed backwards, but apart from that, I can’t figure out how to make this perform better. I’ve got it at a friend’s house who knows digital electronics much better than I, and even he can’t sort out what the problem is.

Any suggestions?

D