Yamaha CS80

hi guys, wondering if you may be able to help.

upon further research into am M-board VCF envelope issue both myself and scott are sharing, i found that the problem is the once the envelope opens, it NEVER closes. i realized that when first powered up, the problem voice card envelope opens properly. it just stays open. so when the voice rotation comes back to it, its still open, hence it sounding like the sustain level is set to an astronomical amount. more specs:

-almost definitely not IG00152. tried with new working chip, and same problem.
-almost definitely not VR 15,18, or 19. replaced VR18(sustain level), and checked impedance of VR 15 and 19. both working.

this leads me to believe that there is failure of another part on the m-board. does anyone know these well enough to take an educated guess here? thanks guys!




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hi guys, wondering if you may be able to help.upon further research into am M-board VCF envelope issue both myself and scott are sharing, i found that the problem is the once the envelope opens, it NEVER closes. i realized that when first powered up, the problem voice card envelope opens properly. it just stays open. so when the voice rotation comes back to it, its still open, hence it sounding like the sustain level is set to an astronomical amount. more specs:-almost definitely not IG00152. tried with new working chip, and same problem.-almost definitely not VR 15,18, or 19. replaced VR18(sustain level), and checked impedance of VR 15 and 19. both working.this leads me to believe that there is failure of another part on the m-board. does anyone know these well enough to take an educated guess here? thanks guys!
I don't see any obvious cause. The sustain level on the filter EG is always zero - the pin is tied to ground - so I don't know how how the EG could be stuck open. Since this is a static/stuck problem, you should be able to trace this with just a voltmeter. I'd pop out the bad board and the same voice card in the other set of eight, set the panel to the same settings and compare voltages. I'd check the control inputs to the EG (AF, DF, RF, AL, IL), the output off the EG (IC 12, pin 3 = TP1). See http://www.therogoffs.com/cs80/pics/page%2041%20-%20M%20Circuit%20Diagram.jpg and http://www.therogoffs.com/cs80/pics/page%2044%20-%20M11-12%20Circuit%20Board%20&%20Wiring.jpg).

It would also be handy if you and Scott could record an audio sample of a good and bad note and put them up in the Files section of the website.

David



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david, thanks a TON for these pointers. just the kind of thing i need, as a newbie to the word of cs80's. here's how the specs shake out:

GOOD VOICE 3: BAD VOICE 3:
AF 1.12V .8V
DF 3.93V 4.5V; 4.42 at trigger, 4.7 at release
RF 8.46V 4.5V; 4.42 at trigger, 4.7 at release
AL 2.54V 2.54V
IL 2.63V 3.3V; drops to 2.84 at trigger
TP1 -.66V;0V at trigger -.66V; .87V at trigger

obviously, there is some discrepancies here, especially at RF.

being a total cs80 newbie, i am still at a loss as to what this means. i will try to record some audio samples and post up later. thanks as always for any help-you guys are brilliant!


David Rogoff <david@...> wrote:
hi guys, wondering if you may be able to help.upon further research into am M-board VCF envelope issue both myself and scott are sharing, i found that the problem is the once the envelope opens, it NEVER closes. i realized that when first powered up, the problem voice card envelope opens properly. it just stays open. so when the voice rotation comes back to it, its still open, hence it sounding like the sustain level is set to an astronomical amount. more specs:-almost definitely not IG00152. tried with new working chip, and same problem.-almost definitely not VR 15,18, or 19. replaced VR18(sustain level), and checked impedance of VR 15 and 19. both working.this leads me to believe that there is failure of another part on the m-board. does anyone know these well enough to take an educated guess here? thanks guys!
I don't see any obvious cause. The sustain level on the filter EG is always zero - the pin is tied to ground - so I don't know how how the EG could be stuck open. Since this is a static/stuck problem, you should be able to trace this with just a voltmeter. I'd pop out the bad board and the same voice card in the other set of eight, set the panel to the same settings and compare voltages. I'd check the control inputs to the EG (AF, DF, RF, AL, IL), the output off the EG (IC 12, pin 3 = TP1). See http://www.therogoffs.com/cs80/pics/page%2041%20-%20M%20Circuit%20Diagram.jpg and http://www.therogoffs.com/cs80/pics/page%2044%20-%20M11-12%20Circuit%20Board%20&%20Wiring.jpg).

It would also be handy if you and Scott could record an audio sample of a good and bad note and put them up in the Files section of the website.

David

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Hi guy's,

Just a guess here but try swapping out the VCF EG's VCA (151)

i knew i was getting a little doughy......but you can see it through my emails? wow. the internet is truly a wonder.

but seriously, did yahoo mess up your reply accidentally? or do i shed the pounds, and THEN gain access to the info that will fix this m-board? if so, you are a genius of richard simmons caliber. im hitting the gym now! i promise!

kent spong <kent_spong@...> wrote: Shed those extra pounds with MSN and The Biggest Loser!
http://biggestloser.msn.com/

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--- In yamahacs80@yahoogroups.com, rj krohn <r_j_d_2.phila@...> wrote:

> TP1 -.66V;0V at trigger -.66V; .87V at trigger

Well, that's the cutoff voltage to the filters, so there is the problem.

--- In yamahacs80@yahoogroups.com, "kent_spong" <kent_spong@...> wrote:
> Just a guess here but try swapping out the VCF EG's VCA (151)

Yeah - I think that's the most likely. You can swap the suspect 151
(IC1) with IC3, which controls the sine-wave level. Luckily, assuming
it fixes it, the CS80 has about a billion of these chips, along with
the other CS and SK synths and many Electone organs from the era, so
it shouldn't be too hard to find a replacement.

Make sure you put it in the right way!

David

thanks a ton, guys. i'll report back with results.



David Rogoff <david@...> wrote: --- In yamahacs80@yahoogroups.com, rj krohn <r_j_d_2.phila@...> wrote:

> TP1 -.66V;0V at trigger -.66V; .87V at trigger

Well, that's the cutoff voltage to the filters, so there is the problem.

--- In yamahacs80@yahoogroups.com, "kent_spong" <kent_spong@...> wrote:
> Just a guess here but try swapping out the VCF EG's VCA (151)

Yeah - I think that's the most likely. You can swap the suspect 151
(IC1) with IC3, which controls the sine-wave level. Luckily, assuming
it fixes it, the CS80 has about a billion of these chips, along with
the other CS and SK synths and many Electone organs from the era, so
it shouldn't be too hard to find a replacement.

Make sure you put it in the right way!

David






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thanks so much for your advice, here guys-you were right! i dropped a new 151 into IC1, and now the envelope is opening and closing properly. the only other issue i have now is that i can now hear the range of the card better, and yet the LPF will not tune into the range of the rest of the voices.

i have 2 more good 00151 chips at my disposal. is there another 151 that possibly drives the 00156 for the LPF? if so, worth a shot? the trim pot isnt shot, as i get some play on both of the VR's that control LPF, it just wont get into a "proper range".

scott-it looks like a new 151 chip at IC1 may solve your issue. give it a whirl....


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Where can I buy this chip you talk about? And David, does this take long to replace?

-Scott



To: yamahacs80@yahoogroups.com
From: r_j_d_2.phila@...
Date: Wed, 5 Mar 2008 17:49:06 -0800
Subject: Re: [yamahacs80] Re: what failed part...you were right! 1/2 way there...




















thanks so much for your advice, here guys-you were right! i dropped a new 151 into IC1, and now the envelope is opening and closing properly. the only other issue i have now is that i can now hear the range of the card better, and yet the LPF will not tune into the range of the rest of the voices.



i have 2 more good 00151 chips at my disposal. is there another 151 that possibly drives the 00156 for the LPF? if so, worth a shot? the trim pot isnt shot, as i get some play on both of the VR's that control LPF, it just wont get into a "proper range".



scott-it looks like a new 151 chip at IC1 may solve your issue. give it a whirl....



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the chip is IG 00151. IC 1 is labeled on the m-board. its a 1-sided
chip. id look around on ebay and such-david says they also were in the
electones, so they should be knocking around here and there.

if you feel comfortable desoldering 7 or 8 pins from a pcb, its easy
as pie. if you havent desoldered chips from a pcb before, i would not
make a cs80 m-board your maiden voyage.(my new hakko desoldering gun
is AMAZING!!! already 1/2 way thru the 4000 series cmos chips in an
hour or two.)

and scott, while my VCF EG is now opening and closing, it did not
solve all my problems. so there is the possibility that IC1 is not
your culprit. if youre sure that your VCF EG is not opening and
closing, this sounds like the best bet, along with replacing the
actual VCF EG chip(00152?)



--- In yamahacs80@yahoogroups.com, Scott Metzger <scottmetzger3d@...>
wrote:

>
> Where can I buy this chip you talk about? And David, does this take

long to replace?

>
> -Scott
>
>
>
> To: yamahacs80@yahoogroups.com
> From: r_j_d_2.phila@...
> Date: Wed, 5 Mar 2008 17:49:06 -0800
> Subject: Re: [yamahacs80] Re: what failed part...you were right! 1/2

way there...

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> thanks so much for your advice, here guys-you were

right! i dropped a new 151 into IC1, and now the envelope is opening
and closing properly. the only other issue i have now is that i can
now hear the range of the card better, and yet the LPF will not tune
into the range of the rest of the voices.

>
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> i have 2 more good 00151 chips at my disposal. is there another 151

that possibly drives the 00156 for the LPF? if so, worth a shot? the
trim pot isnt shot, as i get some play on both of the VR's that
control LPF, it just wont get into a "proper range".

>
>
>
> scott-it looks like a new 151 chip at IC1 may solve your issue. give

it a whirl....

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> Be a better friend, newshound, and know-it-all with Yahoo! Mobile.

Try it now.

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anyone ever compiled or seen a list of other yamahas (the electones
for instance) that use the same ICs as the CS series?

might be a good resource for those of us with CS80 etc..we could find
those gawdy home organs for cheap and harvest the parts rather then
tear up a repairable CS50 or 60.

i know some of those electones use similar (if not the same) pots and
switches as the CS series.

I think I'd feel less bad tearing up a home organ then a synthesizer