Help with small issues and Diagnostic Mode of SY77

Yamaha SY77 is a 16 voice multitimbral music workstation first produced by Yamaha Corporation in 1989. The SY77 is a synthesizer whose architecture combines AFM (Advanced Frequency Modulation) synthesis, AWM2 (Advanced Wave Memory 2) for ROM-borne sample-based synthesis, and the combination of these two methods christened Realtime Convolution and Modulation Synthesis (RCM).

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Zanna1983
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Help with small issues and Diagnostic Mode of SY77

Unread post by Zanna1983 » Mon Feb 05, 2018 9:58 pm

Hi guys,

First of all, since i'm new to this forum, congratulations to all for the great contents of this site!

I just purchased a used SY77 in very good conditions for about € 220,00 and now i'm carefully checking if everything is working fine.

The floppy disk, at first, didn't work but after a cleaning of the rubber belt, now it seems to be fine.

Another issue i'm facing is related to 2 slow keys (D3 and F#3); the return in position of the key after pressing it seems to be slower than the rest of the keyboard. Today I purchased five leaf springs and i'm about to replace the existing ones. Do you think I can solve the problem this way or the reason may be another one ? (Just for information... which is the correct way of disconnecting the smaller connectors on the motherboards ?)

Finally i performed all the test in diagnostic mode and everything seems ok. I performed test 31 to 40 with my oscilloscope (input resistance is 540K ohm) with the following results :

31 to 37 :
L1/L2/R1/R2 : sin wave at 1KHz with peak to peak amplitude 2,42V (expected 1KHz with -1 db on 10K ohm)
Phones: sin wave at 1KHz peak to peak amplitude 5,60V (expected 1KHz with 5 db on 150 ohm)

38
L1 : sin wave at 1KHz with peak to peak amplitude 9,68V (expected 1KHz with 11 db on 10K ohm)

39
L1 : sin wave at 1KHz with peak to peak amplitude 9,52V (expected 1KHz with 11 db on 10K ohm)

40
L1 : sin wave at 1KHz with peak to peak amplitude 8,64V (expected 1KHz with 10 db on 10K ohm)

Since it's a long time i'm not using decibel anymore, i'm having some difficulties checking this data to be correct. Can anyone help me ?

Thank you for all in advance!
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by Sonus » Wed Feb 07, 2018 8:34 am

Hi, voltage gain in dB = 20 x log (V2/V1), doubling the voltage equates to +6dB

Image

Update :!: This is a more accurate table with reference value 0 dBV = 1 Vrms

Image
Last edited by Sonus on Sun Feb 11, 2018 7:34 pm, edited 2 times in total.
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by Zanna1983 » Wed Feb 07, 2018 1:40 pm

Sonus wrote:
Wed Feb 07, 2018 8:34 am
Hi, voltage gain in dB = 20 x log (V2/V1), doubling the voltage equates to +6dB

Image
Thank you very much! It sounds right to me!

My only question is... how do you assumed that 2,42V corresponds to -1db ?
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by MdMax » Wed Feb 07, 2018 10:04 pm

Zanna1983 wrote:
Mon Feb 05, 2018 9:58 pm
Another issue i'm facing is related to 2 slow keys (D3 and F#3); the return in position of the key after pressing it seems to be slower than the rest of the keyboard. Today I purchased five leaf springs and i'm about to replace the existing ones. Do you think I can solve the problem this way or the reason may be another one ?
Hello,

I also had 2 slow keys (A#2 and C#3). A few weeks ago, I checked several leaf springs, I noticed they are not straight like on eBay pictures of similar springs but bent. I decided to flip over the springs on these keys, it solved my problem, and they felt better, so I decided to apply this on all the keys.

Image

I bought my SY77 new, 26 years ago, so I guess the metal got used to this shape and got tired. :wink:
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by Miks » Wed Feb 07, 2018 11:02 pm

MdMax wrote:
Wed Feb 07, 2018 10:04 pm
Zanna1983 wrote:
Mon Feb 05, 2018 9:58 pm
Another issue i'm facing is related to 2 slow keys (D3 and F#3); the return in position of the key after pressing it seems to be slower than the rest of the keyboard. Today I purchased five leaf springs and i'm about to replace the existing ones. Do you think I can solve the problem this way or the reason may be another one ?
Hello,

I also had 2 slow keys (A#2 and C#3). A few weeks ago, I checked several leaf springs, I noticed they are not straight like on eBay pictures of similar springs but bent. I decided to flip over the springs on these keys, it solved my problem, and they felt better, so I decided to apply this on all the keys.

Image

I bought my SY77 new, 26 years ago, so I guess the metal got used to this shape and got tired. :wink:
Please see the last picture on this website (scroll down to the end):
http://bustedgear.com/repair_Yamaha_Korg_keys_3.html

It shows a bent key guide - those key guides can be adjusted with a regular, slip-joint pliers. Maybe this helps...?

P.S. as far as I'm aware those leaf springs are designedly 'pre-bent' a little by manufacturing - it's not because they're 'aging' :wink:
My (key related) gear (in alphabetical order):
Ferrofish: B4000+
Kawai: K1 II
Korg: M1 (up'd to EX, w/ 'Cool Blue'), M1REX (w/ 'Cool Blue'), Poly-800
Roland: D-50, D-110, D-550, PG-1000
Yamaha: AW1600, DX7IID (w/ 'Cool Blue'), EX5R, RM50, RX5, SY99 (w/ 'Cool Blue'), TG500, TX-802, YMM2
Sector101: SYEMB05 (5x), SYEMB06 (3x), EXFLM2 (1kit), MCD Sweet16 (1x), WaveBlade 8MB Card (1x) & 1x Programmer Unit for WaveBlade
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by Zanna1983 » Thu Feb 08, 2018 9:25 am

Thank you guys! Both of you!

I was missing this tutorial regarding removing keys and fixing the springs. It seems to me a very good idea to flip the spring upside-down... hoping that no previous user did the same in the past 30 years :lol:. My only doubt is if it's safe to dismount and remount the whole keyboard... will I face any risk of altering the velocity response or the homogeneity of the aftertouch along the keyboard? (Just wondering...)
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by parametric » Thu Feb 08, 2018 2:14 pm

Probably the best advice is (which you already know . . . :wink: ) is to go SLOWLY and GENTLY . . . .

You have the method now - so just bear in mind that keys especially have tiny plastic appendages that are easily broken.

I don't have an SY77, but a while back, I successfully repaired a badly fitted key contact in my Fusion 6HD . . .

Take time to check everything is bedded down exactly where is should be, and importantly, don't force anything.

Just re-try, even backtrack a little - 'til it fits . . . .

When you are finished - you will know more about the SY than you did before 8)

parametric
Alesis Fusion 8SSD AND 6SSD - BOTH are 384Mb/120Gb SSD/Akai ADVANCE61/Yamaha MOXF6/1024Mb Flash Ram/Yamaha SY85/8.5mb vol/1024k non-vol/DX21/Roland MT32/Bachmann double overstrung Baby Grand Piano/Win10 Pro/Ubuntu MATE 15.0.4/iBook G4/Mac OS 10.4.6/ProTools 7.4/MBox2/M-Audio MicroTrack 24/96

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BRAND NEW DSDD (720k) FLOPPY DISKS FOR SALE - http://www.yamahaforums.co.uk/forum/vie ... =22&t=9217

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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by Zanna1983 » Fri Feb 09, 2018 9:50 pm

This evening i dismounted my SY77; it took me one our to get the keybed out and another half an hour to get all the keys/springs out.

I've got a couple of questions:
- Under the springs there is a small horizontal line, the color is different.. some of them are black, other ones are red...blue... green.. what does it mean ?
- What can i use to clean the plastic of the keys ? Alchool maybe ? And to clean the springs?

Tomorrow i will place the springs back (flipped upside-down) and I will put the keys inside the bed one octave by one.

Thank you for your help and support!
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by parametric » Fri Feb 09, 2018 10:54 pm

Zanna1983 wrote:
Fri Feb 09, 2018 9:50 pm
What can i use to clean the plastic of the keys ? Alchool maybe ? And to clean the springs?
If you are removing all the keys, I would wash them gently in a bowl of warm water with some washing-up liquid.

Do take care, as the keys may have small lugs and protrusions on them that must NOT be broken off.

I would not recommend alcohol for the keys - warm water and detergent should be sufficient.

Gentle use of an old toothbrush may help with hard to reach places or more stubborn dirt.

Rinse with plain water afterwards.

Dry off with absorbent kitchen paper or a new towel, taking great care not to break any small lugs etc . . .

Alcohol will be fine for the springs.

Make sure everything is dry before reassembling . . .

parametric
Alesis Fusion 8SSD AND 6SSD - BOTH are 384Mb/120Gb SSD/Akai ADVANCE61/Yamaha MOXF6/1024Mb Flash Ram/Yamaha SY85/8.5mb vol/1024k non-vol/DX21/Roland MT32/Bachmann double overstrung Baby Grand Piano/Win10 Pro/Ubuntu MATE 15.0.4/iBook G4/Mac OS 10.4.6/ProTools 7.4/MBox2/M-Audio MicroTrack 24/96

NI Komplete11 Ultimate

Sector101 2x SYEMB06 / 4 x EXM-E3 128MB DRAM Module

BRAND NEW DSDD (720k) FLOPPY DISKS FOR SALE - http://www.yamahaforums.co.uk/forum/vie ... =22&t=9217

Watch out now! take care, BEWARE of the greedy leaders! They'll take you where you should not go - (George Harrison)

IT'S TRUE - "MONEY TALKS" - TO ME, IT MOSTLY SAYS "GOODBYE" ;-)
http://www.chrisnmiller.co.uk/Chris
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by Miks » Sat Feb 10, 2018 12:58 am

Para's advices are spot on (Y)
My (key related) gear (in alphabetical order):
Ferrofish: B4000+
Kawai: K1 II
Korg: M1 (up'd to EX, w/ 'Cool Blue'), M1REX (w/ 'Cool Blue'), Poly-800
Roland: D-50, D-110, D-550, PG-1000
Yamaha: AW1600, DX7IID (w/ 'Cool Blue'), EX5R, RM50, RX5, SY99 (w/ 'Cool Blue'), TG500, TX-802, YMM2
Sector101: SYEMB05 (5x), SYEMB06 (3x), EXFLM2 (1kit), MCD Sweet16 (1x), WaveBlade 8MB Card (1x) & 1x Programmer Unit for WaveBlade
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by Zanna1983 » Sat Feb 10, 2018 8:48 am

parametric wrote:
Fri Feb 09, 2018 10:54 pm
Zanna1983 wrote:
Fri Feb 09, 2018 9:50 pm
What can i use to clean the plastic of the keys ? Alchool maybe ? And to clean the springs?
If you are removing all the keys, I would wash them gently in a bowl of warm water with some washing-up liquid.

Do take care, as the keys may have small lugs and protrusions on them that must NOT be broken off.

I would not recommend alcohol for the keys - warm water and detergent should be sufficient.

Gentle use of an old toothbrush may help with hard to reach places or more stubborn dirt.

Rinse with plain water afterwards.

Dry off with absorbent kitchen paper or a new towel, taking great care not to break any small lugs etc . . .

Alcohol will be fine for the springs.

Make sure everything is dry before reassembling . . .

parametric

Well, what can i say.... thank you again man! This afternoon there will be warm water for them! (Y)

Regarding the coloured lines, I will probably ignore them (i think that after washing the springs in alchool they will disappear!)
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by MdMax » Sat Feb 10, 2018 10:21 am

Zanna1983 wrote:
Thu Feb 08, 2018 9:25 am
My only doubt is if it's safe to dismount and remount the whole keyboard... will I face any risk of altering the velocity response or the homogeneity of the aftertouch along the keyboard? (Just wondering...)
Velocity response can be altered if you bend the contacts under the keyboard. The link posted by Miks with the Korg repair tutorial is very good, but I would add one tip here: "The contact pusher also has a cutout. Then hold down the back of the key and push it rearward so the leaf spring slides into its slot, then downward so the back of the key hooks into its cutout."

When you hold down the back of the key to push it rearward for the spring, don't hold the front of the key too low. The contact pusher could bend the contact under the keybed. If it happens, you can easily fix this (straighten the contact very carefully) once you flip the keyboard upside down:

Image

Checking all the key guides is also a very good advice. When I had the problem with 2 slow keys (only sometimes slow), I first thought it must be the keyguide or the grease between the keyguide and the key. I bought white lithium grease is case I would need some before unmounting the keyboard. But I didn't use it. In my case, no real contact with the keyguide when using the keys, original grease was still in place, and the flip of the spring did the work.

You can find nice videos here with a DX7 makeover (it's the same keybed): https://www.youtube.com/watch?v=S3kbhMVSPH4
Zanna1983 wrote:
Sat Feb 10, 2018 8:48 am
Regarding the coloured lines, I will probably ignore them (i think that after washing the springs in alchool they will disappear!)
I guess this must have been a logo or markings on the metal plate before the leaf springs have been cut out. But I really don't know. Most of my springs didn't have any coloured lines.
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by Zanna1983 » Sat Feb 10, 2018 6:15 pm

MdMax wrote:
Sat Feb 10, 2018 10:21 am

Velocity response can be altered if you bend the contacts under the keyboard. The link posted by Miks with the Korg repair tutorial is very good, but I would add one tip here: "The contact pusher also has a cutout. Then hold down the back of the key and push it rearward so the leaf spring slides into its slot, then downward so the back of the key hooks into its cutout."

Checking all the key guides is also a very good advice. When I had the problem with 2 slow keys (only sometimes slow), I first thought it must be the keyguide or the grease between the keyguide and the key. I bought white lithium grease is case I would need some before unmounting the keyboard. But I didn't use it. In my case, no real contact with the keyguide when using the keys, original grease was still in place, and the flip of the spring did the work.
Thank you so much for your help!

I've got three questions at this point...

- Where the lithium grease is supposed to be ?

- How can i straigthen up the springs? ...and which is the correct bending in loose position?

- I noticed that some of the panels of the key contact are not centered in the hole where the hammer strikes... i suppose it's something normal within fabrication tolerances but i prefer to ask to you! Any problem with this ? (no bended contacts till now, i will check carefully after the re-mounting of the keys.
IMG_1617.jpg
Consider that, except 3 slow keys the keyboard was working fine!
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by MdMax » Sat Feb 10, 2018 7:58 pm

Zanna1983 wrote:
Sat Feb 10, 2018 6:15 pm
I've got three questions at this point...

- Where the lithium grease is supposed to be ?

- How can i straigthen up the springs? ...and which is the correct bending in loose position?

- I noticed that some of the panels of the key contact are not centered in the hole where the hammer strikes... i suppose it's something normal within fabrication tolerances but i prefer to ask to you! Any problem with this ? (no bended contacts till now, i will check carefully after the re-mounting of the keys.
The grease is supposed to be on top of the keyguides where the keys could touch the guides:

Image

You can learn more about this here: https://www.justanswer.com/electronic-m ... sizer.html

Don't straighten up the springs. Only straighten up the contacts under the keybed if they are bent when you mount the keys. You'll see this once you'll return the keyboard but if all the keys are working fine, you don't need to change anything. Also don't care about the fact that some of them are not centred.
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Re: Help with small issues and Diagnostic Mode of SY77

Unread post by Zanna1983 » Mon Feb 12, 2018 10:41 am

MdMax wrote:
Sat Feb 10, 2018 7:58 pm
The grease is supposed to be on top of the keyguides where the keys could touch the guides:

Image

You can learn more about this here: https://www.justanswer.com/electronic-m ... sizer.html

Don't straighten up the springs. Only straighten up the contacts under the keybed if they are bent when you mount the keys. You'll see this once you'll return the keyboard but if all the keys are working fine, you don't need to change anything. Also don't care about the fact that some of them are not centred.
Thank you!

I noticed that on the low notes grease condition is ok while in the rest of the keyboard I think it's too "dry". To be sure of the result i'm actually degreasing all the guides (long and boring job :cry:) with a general pourpose degreaser which is not aggressive on plastics. I ordered a White Lithium Grease bottle and tomorrow i will start to put the grease back (i suppose it shall be placed on top and sides..).
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