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Old 10-02-2018, 06:01 PM   #81
dkneyle
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Default Re: Yamaha Electric Piano CLP550 no keyboard output

If, as it appears, your ROMs have rotted over time, then there is hardly any point trying to pull them and read the codes. That's what I did; sent them off to an enthusiast in the UK who read them and confirmed they were corrupt. Unless someone manages to get a good read of all three ROMs you (and anyone else with the same issue) have no chance to get things going again. With the correct ROM code it is simply a matter of burning to compatible EPROMs. But we need the good code first.

Sorry my friend, but you have gone up the same dry gulch as many before.
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Old 11-22-2018, 09:24 AM   #82
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Smile Re: Yamaha Electric Piano CLP550 no keyboard output

Hello friends, Thanks for the lot of effort made on the clavinova 550 so far. me too now having a unit to repair with NO sound or some strange distortions on certain key puches. so i follow the whole thread and learn alot.

i had gone through my case before read this thread and refering the circuit diagram and i was end up with decision to change the DAC chip first. but it seems i have more things to consider.

i noted the circuit of my case had not done any repair so far and problem occurred after idle for year or so. so im quite convince the fault will not cure after replacement of DAC and few other digital chips support mux n chip enables(Hex inverters). anyway im trying my luck in coming few days if i was able to procure the DAC locally or i have to wait 3~4 weeks to arrive it from Ebay. in the same time im planning to remove ROMs carefully to read them and make a dump. fortunately i have all the stuff to do so with me already. if the luck is in our side n if we able to read ROM-A, we have have whole lot with collection of your previous efforts.

i had checked the availability of 27C040 ROMS( or even AT27C040 from ATMEL from more recent era) and those are available to order and my EPROM reader\programmer well supporting those. so hope for the best!

Thanks guys for your endless effort from 2014, long way back!, will update you the progress!

by the way: let me introduce my-self, im PMD from Sri Lanka, Engineer and experienced Repairman(as part of the job and as a hobby) for many years. experience in Electronics, component level repairs in analog and digital systems, embedded system design and programming, Electrical Engineering...

PMD.
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Old 11-22-2018, 04:00 PM   #83
dkneyle
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Default Re: Yamaha Electric Piano CLP550 no keyboard output

It certainly appears that if the piano is not used for a period of time then the ROMs fail. Reading this thread, that appears to be a common theme. I too changed the DAC but of course that didn't fix the problem. So if you are able to recover good code from the final ROM then perhaps there is a pathway to reflash some ROMs and get it going? Even though I no longer have the piano (actually I could still access it if I hear that anyone succeeds with this strategy) then it would be a great conclusion to this thread.
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Old 12-10-2018, 01:36 AM   #84
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Default Re: Yamaha Electric Piano CLP550 no keyboard output

I was working on my CLP550 and got replacement EPROM AM27C040 and had read my existing chips. two were readable quite well and files attached here. basically the missing image from previous attempt also recovered. but only one rom we both recovered by seems some slight differences in some areas. pls refer attached images if any one interest to some forensics. i manged to read rom A & C. third ROM was just reading first 2 or three bytes but from that point nothing readout. i dont have control over reading pulse time of data settling time after address latch. so might get better results with slower clocks. my reader took around 7500ms to read the whole memory, 14us per byte, might be ok.

will update after while the developments.
Attached Files
File Type: rar Wave Rom Images.rar (404.9 KB, 10 views)
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Old 12-10-2018, 04:25 PM   #85
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Default Re: Yamaha Electric Piano CLP550 no keyboard output

STJ is the expert here who knows about ROM chips. He might be in a position to understand the discrepancy in the code recovered from those two chips. What we really need now is someone with a defective piano to burn the code to new EEPROMs, install and see if it brings the piano back to life.
We have never categorically determined the ROMs to be the problem, although STJ did confirm that the code in my ROMs was garbage or unable to be recovered.
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Old 12-11-2018, 06:38 PM   #86
eccerr0r
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Default Re: Yamaha Electric Piano CLP550 no keyboard output

The 27C040 4Mb/512KB 32-pin EPROM is an asynchronous read unit, and the only sequenced section is reading the deviceID and manufacturerID. These typically have less than 100ns read times so 14s/byte is reasonable.

These are wavetable ROMs? What happens if they get interchanged?

What do you mean by "nothing readout" and "first 2 or three bytes"? What are you reading out on the "bad" one, as they are asynchronous they shouldn't give much information about read failures, just returns bad information.
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Old 12-12-2018, 05:14 AM   #87
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Default Re: Yamaha Electric Piano CLP550 no keyboard output

Yes, it is our understanding they are wavetables. Not sure if they are interchangeable or not? The circuit diagram certainly shows some logic goes on concerning the chip select (CS) line, which might suggest they are intended to only go in the dedicated slot they are intended for?
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Old 12-15-2018, 10:04 PM   #88
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Default Re: Yamaha Electric Piano CLP550 no keyboard output

hi, i were managed to check the CLP 550 with 27C040 ROMs burn with given images. and piano is working!!. i checked the DA converter as well but it working fine. i think previous conclusion of wave ROMs are rotten is correct. even i read the two ROMs just after remove from the board but does not respond to reader few days afterward(i just wanted to read again and compare few reads to see how much consistent the contents of ROMs). but no chance now.

Quote eccerr0r:
"What do you mean by "nothing readout" and "first 2 or three bytes"? What are you reading out on the "bad" one, as they are asynchronous they shouldn't give much information about read failures, just returns bad information. "
I try to read the 3rd chip but after first 2 or 3 address, all remaining adress readsout "FF" or yeilds no output so my output window just shows 1F, 03, A2 then FF, FF, FF till the end. seems chip have error in address decoder area.

with ROM B and C unit is working almost. only the default tone(Grand piano-1) chord area working and reaming keys giving no output but all other 7 tones working. with given ROM A, remaining areas also working, but in my case some noices are added witch i cant eliminate(to all the tones with or without ROM A). i suspect two reasons. one is some data bytes of the roms are incorrectly reads and that causes the issue. also i notices IC15 & IC16 getting some decoding pulses from IC12 and it does the stereo decoding and having some voltage issue in SH3 pin(only 0V - no change over any tone or any function). im further checking on changing these digital chips and let you know in due course. i found all the voltages in remaining areas correct. any suggestions and guide lines are mostly welcome. my CLP550 tones getting slight distortion and at the end of the tone the distortion can here quite well and once toning period end, all noises vanished.
Attached Images
File Type: jpg 1.jpg (558.7 KB, 7 views)
File Type: jpg 2.jpg (500.1 KB, 6 views)
Attached Files
File Type: rar clp 550 CLAVINOVA.rar (751.4 KB, 2 views)
File Type: rar CLP550_OA_C.rar (563.6 KB, 2 views)
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Old 12-18-2018, 11:25 PM   #89
dkneyle
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Default Re: Yamaha Electric Piano CLP550 no keyboard output

Great to know. You have proven it is the ROMs which are at fault. Well done, and now we have a copy of Yamaha's ROM code available in the world wide web!
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Old 12-21-2018, 06:26 AM   #90
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Default Re: Yamaha Electric Piano CLP550 no keyboard output

Quote:
Originally Posted by PMD View Post
hi, i were managed to check the CLP 550 with 27C040 ROMs burn with given images. and piano is working!!. i checked the DA converter as well but it working fine. i think previous conclusion of wave ROMs are rotten is correct. even i read the two ROMs just after remove from the board but does not respond to reader few days afterward(i just wanted to read again and compare few reads to see how much consistent the contents of ROMs). but no chance now.

Quote eccerr0r:
"What do you mean by "nothing readout" and "first 2 or three bytes"? What are you reading out on the "bad" one, as they are asynchronous they shouldn't give much information about read failures, just returns bad information. "
I try to read the 3rd chip but after first 2 or 3 address, all remaining adress readsout "FF" or yeilds no output so my output window just shows 1F, 03, A2 then FF, FF, FF till the end. seems chip have error in address decoder area.

with ROM B and C unit is working almost. only the default tone(Grand piano-1) chord area working and reaming keys giving no output but all other 7 tones working. with given ROM A, remaining areas also working, but in my case some noices are added witch i cant eliminate(to all the tones with or without ROM A). i suspect two reasons. one is some data bytes of the roms are incorrectly reads and that causes the issue. also i notices IC15 & IC16 getting some decoding pulses from IC12 and it does the stereo decoding and having some voltage issue in SH3 pin(only 0V - no change over any tone or any function). im further checking on changing these digital chips and let you know in due course. i found all the voltages in remaining areas correct. any suggestions and guide lines are mostly welcome. my CLP550 tones getting slight distortion and at the end of the tone the distortion can here quite well and once toning period end, all noises vanished.
Dear PMP

Could you please describe in detail how you read the chip. How did you manage to unsolder them or somehow did you connect to them on the board? what application did you use. In short the whole setting.

I am not bad a diy and electronics but reading damage chip on a board would be a first for me.

I have a "dead" clp 550. I would like to extract whatever rom possible so we could compare them and make an educated choice for flashing them onto the 27040 chip

Thank you in advance for your help
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