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by shadowmask
Sun Jun 23, 2019 8:35 am
Forum: For Sale
Topic: Another GREAT Deal from Cloud Cuckoo Land
Replies: 6
Views: 124

Re: Another GREAT Deal from Cloud Cuckoo Land

Indeed Chris, yet another "VERY RARE" item on eBay :P

One of these sold a while back for £150..
https://www.ebay.co.uk/itm/Studiomaster ... 4188573889

It didn't demand the same price as is was not "VERY RARE".

Brian
by shadowmask
Mon Jun 17, 2019 7:09 am
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: TG77 and MCD64 write protected error
Replies: 18
Views: 491

Re: TG77 and MCD64 write protected error

The card won't come apart without a bit of persuasion. If you lever it open the metal covers will distort. To do it without damage I used a heat gun to soften the glue and gently levered the covers off using a thin steel ruler. Patience is the key.

Brian
by shadowmask
Sun Jun 16, 2019 7:59 am
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: TG77 and MCD64 write protected error
Replies: 18
Views: 491

Re: TG77 and MCD64 write protected error

Without knowing what is going on inside the MCD card it would be wise to keep it out of the TG77.

Here is an MCD card fault example.

Brian
by shadowmask
Fri Jun 14, 2019 7:52 am
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: TG77 and MCD64 write protected error
Replies: 18
Views: 491

Re: TG77 and MCD64 write protected error

It is possible that the TG77 tries to verify the format but it is finding invalid data so just assumes the card is protected. MCD cards have a history of becoming faulty over time but as it is working with the SPX that idea seems unlikely. The fault then points to the TG77. The TG77 card connector i...
by shadowmask
Thu Jun 13, 2019 10:34 am
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: TG77 and MCD64 write protected error
Replies: 18
Views: 491

Re: TG77 and MCD64 write protected error

The TG77 service manual shows some tests that can be performed on the card: https://www.sector101.co.uk/external/forums/yamaha_tg77_sm.pdf The Test Programs start at Page 21 The WP switch controls two circuits: 1. It sends a signal to the TG77 to indicate that the switch is in the WP position 2. It ...
by shadowmask
Thu Apr 11, 2019 5:05 pm
Forum: For Sale
Topic: Another MA-36 for Sale
Replies: 12
Views: 494

Re: Another MA-36 for Sale

I never quite got that working and it was disassembled for other experiments. I have seen other monitor projects on the web, one was using a two row LCD if I remember correctly.

Brian
by shadowmask
Thu Apr 11, 2019 1:45 pm
Forum: For Sale
Topic: Another MA-36 for Sale
Replies: 12
Views: 494

Re: Another MA-36 for Sale

Usually they go for £30 - £40, but this one ended at £150 8O

Brian
by shadowmask
Sun Feb 03, 2019 8:48 am
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: SY77 booting in a loop
Replies: 122
Views: 8111

Re: SY77 booting in a loop

IC123, IC124, IC125, IC126 contain the bulk of the OS Firmware. The first block is in the CPU. The block in the CPU contains vectors that point to the routines that handle interrupts, timer overflows etc. If the version in the CPU doesn't not match the version in IC123-126 then nothing is going to w...
by shadowmask
Wed Jan 30, 2019 9:09 am
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: SY77 booting in a loop
Replies: 122
Views: 8111

Re: SY77 booting in a loop

It would be worth the time to check out the PSU properly. As well as the voltage levels check the quality of the regulation. Get a scope and check for excessive ripple - anything over 400mV may cause problems. The PSU appears to be the older linear type supply so probably less prone to the high freq...
by shadowmask
Fri Jan 25, 2019 1:44 pm
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: SY77 booting in a loop
Replies: 122
Views: 8111

Re: SY77 booting in a loop

Most of the SY/TG series used the H8.

Brian
by shadowmask
Sat Jan 19, 2019 8:48 am
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: SY77 booting in a loop
Replies: 122
Views: 8111

Re: SY77 booting in a loop

Edit: after some reading I understand why this chip was used. zero turn around time for product development. There was a mask rom version as well. By the time Yamaha had made my SY85 they had switched to the MaskROM version of the CPU. I did try to extract the code from the CPU but it didn't respon...
by shadowmask
Sun Jan 13, 2019 1:52 pm
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: SY77 booting in a loop
Replies: 122
Views: 8111

Re: SY77 booting in a loop

Best to keep the firmware version from your CPU. I don't know what date the code is from my CPU. Also, the CPU code needs to match the code in the other EPROMS so this would cause further problems.

Brian
by shadowmask
Sun Jan 13, 2019 11:34 am
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: SY77 booting in a loop
Replies: 122
Views: 8111

Re: SY77 booting in a loop

If your programmer supports reading the device ID code then try that before doing the programming. For the HN27C256 (CPU emulated EPROM) the manufacturer ID is 07, Device code is 31. This will confirm that basic communication is working between the programmer and CPU.

Brian
by shadowmask
Sun Jan 13, 2019 11:13 am
Forum: Yamaha SY85 Forum - Covers the SY85 Keyboard and TG500 Module
Topic: Yamaha SY85 No Sounds and Broken Floppy Drive
Replies: 7
Views: 322

Re: Yamaha SY85 No Sounds and Broken Floppy Drive

The onboard battery in my SY85 (and TG500) was the bigger CR2450 type. I think they went for that one as it is used as the backup power for the SYEMB06 modules as well as the onboard memory.

Brian
by shadowmask
Sun Jan 13, 2019 11:10 am
Forum: Yamaha SY77 Forum - Covers the Sy77 Keyboard and TG77 Module
Topic: SY77 booting in a loop
Replies: 122
Views: 8111

Re: SY77 booting in a loop

I've been looking forever for the CPU code for the SY85 V1.34 but came up with nothing except the option of buying the CPU pre-programmed for much more than the SY85 is worth. I do have the EPROM V1.34 but no luck running that with the Sub 1.30 CPU code. The H8/532 appears to address the memory map ...

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