Moonsound v1 issue

Champion (381)

07-04-2021, 18:40

I am trying to upgrade the Moonsound v1 to 512K. We replaced the CXK581000 ram with an Alliance AS6C4008. We also added the A17 line to the pin 74 of the OPL4, which was previously not connected at all.

When I test the Moonsound I come across two issues:
* Moontest by Alexey Podrezov sometimes does not detect the SRAM. But if it does, it fails in all three steps. I have tried loading a MBK and saving it again, which result in a different file every time I save it. In sort, the SRAM does not work. Maybe somebody has done this upgrade as well and we are missing something (i.e. the chip select signals)?

* The sound is corrupt. Even when I try MBFM without MBK or roboplay with a OPL3 tune. I sounds like the DAC is defective, does anybody reconise this problem? I have ordered a new DAC already.

Listen here (loud noise warning) while playing the ROM

By Wierzbowsky

Guardian (3651)

07-04-2021, 19:08

There are a lot of fake/broken SRAM chips. My Wozblaster had to be fixed just after assembling because the chips were busted. Some of RAM expansions also had issues because of non-working SRAM chips. So, I always buy from this seller as his chips were always 100% working:

https://www.aliexpress.com/item/32791245232.html

By SjaaQ

Champion (381)

07-04-2021, 19:47

The ram chip came from https://nl.rs-online.com/web/p/sram/7444561/ which is a trustworthy supplier. But if you suspect the ram being faulty, I can order some more from aliexpress.

I have not seen any instructions on how the expand the Moonsound v1, I don't see a reason it won't work. Maybe somebody has some experience with it.

I was also wondering if it might point to the OPL4 failing. Also because the FM synthesis produces the same digital noise.

By Wierzbowsky

Guardian (3651)

08-04-2021, 00:53

Just to clarify - I didn't say that your RAM was faulty. It could be OK, but the way it's connected might be wrong. I just shared my experience with those RAM chips that caused the sample instrument distortion on my newly-built Wozblaster. So, until you get some piece of advice on how to check whether you assembled everything correctly, I would not consider changing the RAM.

By Angelo Sanna

Expert (69)

08-04-2021, 01:28

SjaaQ wrote:

The ram chip came from https://nl.rs-online.com/web/p/sram/7444561/ which is a trustworthy supplier.

That's indeed true. RS is a renowned company (since 1937) that delivers quality and purchases from major manufacturers that supplies the professional market.

The Ali Express link from Alexy is SMD SRAM, yours is THT (Trough Hole Technology). Look at the photo: photo-SOP32

So if you plan to use the AliExpress SMD SRAM, you must make a adapter-print or something like that to fit on the PCB. So I think this is not the solution you are looking for. Can you tell me where you have the upgrade schematic? Link or something would be handy. Can you post this here?

By SjaaQ

Champion (381)

08-04-2021, 08:23

There is no updated (or even orginal) schematic. We compared the pinout of the Sony and the Alliance chip and only figured the A17 connection was missing.

I have been looking for schematics, but could not find any. I used the Wozblaster schematics and figured Moonblaster should use kindof the same for the ram connections.

By sdsnatcher73

Enlighted (4307)

08-04-2021, 09:39

Maybe the ROM and RAM have overlapping addresses now? What happens if you disconnect the RAM?

By SjaaQ

Champion (381)

08-04-2021, 10:58

The ram is not in a socket because it wouldn't fit in a case anymore. There is currently not an easy way to "disconnect' it.

I am going to to try the Alliance ram (another one) in a Moonsound v2 first (which has a spare socket and actually is said to support an additional 512K chip). I need to pick it up from a friend first.

By Angelo Sanna

Expert (69)

08-04-2021, 22:15

SjaaQ wrote:

There is no updated (or even orginal) schematic. We compared the pinout of the Sony and the Alliance chip and only figured the A17 connection was missing.

I have been looking for schematics, but could not find any. I used the Wozblaster schematics and figured Moonblaster should use kindof the same for the ram connections.

You could try ask Eugeny about this, he is very known with electronics. He is the designer of the Gr8net cartridge. And it is generally known that Russians are good at it. ;)

By SjaaQ

Champion (381)

10-04-2021, 17:32

I now have the Moonsound 2.0 and put in (a new) Alliance chip, which gets detected, but only 256K total. I guess there should be something jumpered, but there a no jumpers actually mounted. So I need to get that fixed as well.

Anybody that knows how to set the jumpers for 640K? Is that even possible? The "instructions" printed on the board make no sense to me.

By sdsnatcher73

Enlighted (4307)

10-04-2021, 18:52

It seems default position (unconnected?) for J3 and J4 are 128kB (the MoonSound above has 2 128kB RAM chips). I would suspect J3 is for the lower RAM chip and J4 for the upper one. J2 is a bit unclear. You could put in the pins for the jumpers and play around with jumping J2, J3 and J4 between 1-2 and 3-4 positions a bit. It seems mixing 128kB and 512kB was an option but otherwise you could first try with just a 512kB in the lower spot (and go for 2 512kB as a next step)