Yamaha vss30 service manual here

[gmeredith]

I found this while doing a search. It says it has the schematics, good for bending info.

http://www.manuals-in-pdf.com/advanced_search_result.php?keywords=yamaha+vss30+service+manual&forward=plist

If anyone buys this, can they tell me the name and the type of chip that the RAM chip is? Or for that matter, can someone open up their vss30 and write down what's written on it. It's the 16 pin chip that everyone connects their sample bend wires to. I may be able to replace the chip with one that remembers its sample, even when switched off! No promises that it will be possible, but maybe...

Cheers, Graham

[Circuitbenders]

RAM chip says MB81256-12 on it, theres loads of references if you do a search on google although i couldn't see a data sheet.

[gmeredith]

Thanks for that, I'll see what can come of this.

Cheeers, Graham

[gmeredith]

Alas, it seems that the vss30 has DRAM for memory, according to the datasheet I found for it. Which means that it can't be sustituted for another chip with memory retention (as far as I know).

I don't know if this is also true for the vss100 - it can hold 4 samples - so it may have a different chip. Anyone got a vss100 and can tell me what RAM chip is in it? I could see if there is a sustitute for it.

As for the vss200, it seems to be the same in its sampling section as the vss30, so I don't expext anything can be done about it.

Other samplers, such as the Casio sk1/5/8 can have their RAM swapped (they have SRAM) for NVSRAM (non-volatile SRAM), which means for the SK1, you can swap its 2 SRAM chips for 2 NVSRAM chips that remember their memory when the power is turned off, such as these:

http://focus.ti.com/docs/prod/folders/print/bq4010y.html

The SK5 and 8 already retain their memories when using batteries, so it's not really an issue with them. It's a damn shame about the Vss, though. The sampling part of that keyboard seems so much better than the SK's, according to everyone.

Cheers, Graham

[bendboy]

Hmmm.... I had wondered if anyone had 'cracked' the SK-1 ram save problem.....have you done the mod? Does the CPU 'know' it is still programmed when turned on? I ask because bus activity at turn-on might mean the CPU is clearing out the rom at turn-on (and disconnecting the auto shut-off pin make the keyboard stay on, but the CPU still goes to sleep!!

[gmeredith]

I haven't done the mod for the SK1 (only on the SK8), but the sk1 memory upgrade, as far as I understand, would behave similarly to an SK8 that doesn't have batteries in it. That is, when you switch it off, with no batteries installed, and then switch it back on again, the processor would behave like an SK1 and think that there is no samples stored in RAM, even if there is (the processor has a small RAM memory to tell it where to find things) .

To get the SK8 and SK1 to "find" the samples previously stored, a memory protect switch is connected to the RAM chip (to its "write enable" pin) and put in the protect position, and a fake sample record is done, by speaking into the microphone after hitting the sampling button. When it finishes the "sampling", instead of hearing what you just spoke in the microphone, you will hear the sample that you originally saved to the RAM.

The sequencer data is also stored in the sample RAM, so it will also retain it, but "forget" where it is - you just do the same thing as the sample trick - set memory switch to "protect", record a quick random sequence. When you hit play, your proper, previously recorded sequence will come out instead.

What will be lost each time will be the envelope you had on the sample, so you'll have to choose the envelope for the sample again. Also any sounds made using the synthesis section will be lost. Both of these memories are stored in the processor RAM, so they won't be saved by the memory upgrade.

Check out the 32x memory expansion and other SK5/SK8 mods here:

http://www.jz-server.de/forum2/e107_plugins/forum/forum_viewtopic.php?125

and a simple 2x memory expansion for the SK5/SK8 here:

http://www.jz-server.de/forum2/e107_plugins/forum/forum_viewtopic.php?22

- bear in mind that although these expansions are for the SK5 and 8, you can adapt them easily by the same principles to the SK1 (except that you'll need 2 RAM chips for the upgrade because the SK1 has 2 RAM chips, as opposed to the SK5/8, which have only 1)

Cheers, Graham