NEW TITLE: DX7 help

[rhino]

hey gents:
anybody have a working Casio CZ-1 in their trove? This one is driving me CRAZY!!!!
bought a used RA-6 RAM cart from ebay right after i got the keyboard (six months now)
just now got it playing reliably. put a new battery in the cartridge and tried to save to it. fail.

here's the situation:
the card will load the garbage in it to the synth, all at once or one patch at a time.
trying to save the entire synth bank to the card results in "CARD NOT READY"

now the crazy part: you can save a single patch from the synth to the card, but only EVEN NUMBERED ONES: A-2, A-6, B-4, etc.

my question:
can i send the cartridge to someone to try in another CZ-1? I'd pay postage and insurance both ways.

new battery, ohmed all flat cable traces, viewed card internal board to look for visual problems.

thanks

[rhino]

thanks for the offer, Madtheory. (message p.m.'d)
i've ordered a 74LS374 chip (octal tri-state latch - seems to have two open pins) and will see if that improves the outlook (and my mood).

[madtheory]

No prob. Where does that chip go? I'm familiar with it from Logic Gate labs of old

[rhino]

it and a 74LS174 hex latch make up the access port for the cartridge. they are located on the main board right under the RAM/ROM slot.

[rhino]

thanks Madtherory.

replacing the 74LS374 chip cured THAT problem. Saves and loads to card fine now.

intermittant non-working 'MIDI on/off' LED was traced to a cracked foil in one of the flat cable interconnects.

[Pro5]

Anyone know the equiv of this chip on a DX7 II-D (and how to test, can it be done with a multimeter?). I have an intermittent/quirky fault when using carts on it.. have checked the PCB over very closely, tested lots of pins/tracks etc and can't find anything 'obvious' so wondering it's a bad IC or other component.

I can see 74ls244 74ls365 74ls174 etc

thanks

[rhino]

dont know what help this will be.

ICs 13 and 19 are the data latches for the cartridge. ICs 8, 17 and 33 seem to be part of the 'select' logic drive. You'll need a 'scope or at least a logic probe to test further.

[Pro5]

THanks... shame I need some more gear to test though was hoping it would be some easier / obvious fault. Synth works perfectly apart from this. (tried a rom and ram, contacts are fine etc)... battery good...

I select the bank (1 DX7 2 format).. then when I select voices it works ok.. but at 'random' I will get cart format error on the LCD.. and checking the bank select it will have changed 'by itself' to bank 10 or something... it's quite random... even selecting voices via midi does it but..it's slightly diff (sometimes the error takes longer to show). Setting it back to the correct bank then works for another few presses...

hmmm

[Pro5]

I did notice there was a very thin 'scratch' across a bunch of tracks that go down to the cart connector/IC13 - testing for continuity was ok but on one track the conductive material shows through (and can be also tested there)... so the continuity is ok with a multimeter but is there a chance that when real power is supplied this 'scratched track' could become overloaded and flake out??? (sorry my knowledge of PCB electronics is pretty basic and unpracticed for years)

The only other thing I can see is possible liquid/gunk at some point in the past (arrow 2) - the board looks clean apart from that and I can't see any obvious bridging/shorts...

here's a pic (in case anyone else has any ideas) and sorry for the thread hijack. The 'scratch' looks worse on here than in real life and as I said I checked continuity from end to end and it seems ok...




Thanks

[rhino]

MODS: you may want to break this out into a new thread thanks.

i doubt the scratch is a problem if ohm-meter shows ok, just in case, you might try flexing the board slightly while the meter is on.

cartridge slots are a favorite target for spilled beer or soda. long shot, but try wiping the board and socket with cleaner or 95% alcohol.

is the problem the same on all carts?

next, i'd try heating/cooling the IC mentioned above. you can get cooling spray at Ratty-ol'-s**t, and use a hair-dryer for heat.

any other problems with patch=data changing itself, stuck notes, lockups?

[Pro5]

NO problems at all aside from this. When selecting a new patch (either voice or performance) the LCD will show random chars "fffffff *************" etc (for the patch name) and then 'cart format err'. I can select sometimes ok, there's no pattern to it all (i.e certain numbers better than others) it's just 'eventually' some press of the 32 buttons (or even via midi) when using 'cartridge' will throw this error (and no lockups - i can either go into edit/cart and change back to bank1/dx72 format or just hit internal and select an on board voice ok).

Thanks for the help I will try as above but if it don't sort it soon, I'll just re-assemble and get on with using it (I miss using it!), I can live without cart access in this day n age but would have liked to get it working. Will be selling RAM4 cart and IID/FD Rom on ebay if I can't use them I guess (oh I bought the Ram4 cart afterwards to see if that would work but also has strange errors - like saving, says its all gone good but then next time it's still the old patch on it - cart is OK)

thanks

[rhino]

the random nature of the problem and the 'scrambled' names still makes me think that there is a failing logic chip in the cartridge port area. Maybe time to take it to someone who knows more than I.

[Pro5]

yes... and thanks for renaming your topic

Well the synth was very cheap and in VGC aside from this problem, everything else functions as I'd expect so... until a time I want to sell it on (unlikely) I guess I'll just live with it, have a feeling any expert could end up charging me more than the Synth cost (under £100 if I deduct it's hardcase cost that I also got with it)

thanks again. will try some things tomorrow and if no joy then it's re-assembly time