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Re: Roland RA-50 Mod

Posted on 2024-05-02, 16:00

Hey Tiido! That’s a great spot! On mine, it looks like it has been simplified to R70 and R69, with the spot where R68 should be actually being a bridge to ground. IMG_2300.jpeg I lifted 70 and 69, and cut the bridge, but alas no change. Odd! I’ve put them back now anyhow. It may remain an unsolved …

Re: Roland RA-50 Mod

Posted on 2024-05-02, 06:24

My board has the R15209214 masked ROM on it. Just had a quick google and people have verified seeing this on both the LAPC-I and CM-32L, so I'm pretty sure that's OK. Had another look over the schematics for the CM64 and the later rev MT32 to see if there was anything obvious, but it seems not. How …

Re: Roland RA-50 Mod

Posted on 2024-05-02, 05:24

Well, I'm still awake due to the effects of this illness causing me to struggle to sleep... yay. Anyhow, I have at least worked out *why* the sounds aren't appearing. They aren't being mapped! Not sure why this is, as I'm pretty sure all RA-50s came with CM-32L ROMs - earlier ones had socketed …

Re: Roland RA-50 Mod

Posted on 2024-05-02, 01:51

Sorry for the late reply but I’ve been ill. Finally soldered VPP to VCC and I think it fixed it! I’ve tried with Leisure Suit Larry and believe that it does in fact appear to be working! As per another thread here, the song ‘Salsa This’ uses the new laughing sample and I can hear it. Other …

Re: Roland RA-50 Mod

Posted on 2024-04-27, 16:16

I’ve been poring over the data sheets and I think I’ve spotted my mistake. I’ve not connected VPP, as I assumed that it was only required for programming and not when in use… unfortunately I removed the leg, thinking it wouldn’t be needed! I’ve just ordered a dremel to grind away some of the chip …

Re: Roland RA-50 Mod

Posted on 2024-04-27, 15:04

So I committed to it and soldered the chip in place, just in case there were bad connections. Unfortunately it seems that it still isn’t working. Comparing to Phil’s computer lab video on the MT32 and CM32, I’m still getting the MT32 sound effects for beneath a steel sky. Not sure what’s next for …

Re: Roland RA-50 Mod

Posted on 2024-04-27, 12:22

So, I gave this a go using the piggybacked chip method, but sadly to no success. Got a M27C4001 PROM and burned the upper half of the CM32L PCM ROM to it. Got a SN74HC02N and wired it as follows: 74x02.png Pin 2 of the SN74HC02N was soldered to the CE line on the original ROM, and pin 1 to the CE …

Re: Roland RA-50 Mod

Posted on 2024-04-20, 09:58

Ah 0kay- I assumed it was the same CM32L ROM already in the RA-50 as it is labelled as such. I'm still a bit lost as to what needs to be done (electronics isn't my strong suit!) Replace CM-32L ROM on board with 'actual' CM-32L ROM Flash CM-32L PCM ROM onto 27C801 chip. Piggyback burned PCM ROM chip …

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