Re: Dead CS80 - finding a short
Extremely sympathetic regarding the failure! This is just a thought, as more investigation is very likely needed. When you did your PSU rebuild, did you replace this transistor here, and the one in front of it?
|
Dead CS80 - finding a short
So my beloved CS80 died on me after calibration and tuning. To resume: 1. After calibrating BA, KAS and M-boards, 4th M Board 1-channel did not play funky3, memory 1,3 and panel presets (last 4). 2. After inspecting BA board for the possible cause of this the PSU died (played a low note for the few seconds first). 3.Rebuild and calibrated PSU - Died again after power on (also low note first). 4. The upper GND and lower 15V rails are shorted! 5. I?ve tried to find a short isolating -6,5 and 8,5V terminals on the KAS, S/H, KBC 1 and 2 boards - no success (desoldered the wires and the ground and checked with my DVM for continuity - there were no shorts).
I am out of ideas. If the rails for GND and 15v are shorted does that mean that I should repeat the point 5 but between +15v and E terminals on every possible board? Seems logical. I would appreciate any help.
|
Re: Tuning..again - Transposition gate zeroing?
Changing 4558 IC on the PSU cured it again...All the voltages are back - phew! I won?t turn it again until I find out what is killing my PSU. Could it be the BA board?
|
Re: Tuning..again - Transposition gate zeroing?
A little update: 1. Recapped the PSU. - still bad - showing 7,4V instead of 15V for example. 2. Changed the two 1ohm ceramic resistors - helped ! I could calibrate the PSU now. 3. Calibrated PSU - reinstalled. 4. Should I try it out? Yes. I`have tried. 5. Turned the synth on - lights did not come up, same low single note played. Turned it off quickly.. 6. PSU is bad again (showing 0,2V on 15,0 terminal)....resistors seem not burned this time, caps seem intact. 7. Back to square one....I have no idea what is causing this...
|
Re: Tuning..again - Transposition gate zeroing?
Well, it got even better. I?ve tried to fond a possible short and the only board except of M boards I have removed was the BA board (4.0V adjustment). I've inspected it and it seemed fine. After I put it back in and power up the synth it played a low note and died. There was a smell of something burned so I?ve turned it off immediately. Now the PSU is dead. No power. All the fuses intact.. I will recap it and see if it will help but I am pretty mad cause I took extra care while handling this synth and even the fuses did not save the day.? Visually nothing is wrong with the PSU. No leaking or signs of burned components. The only thing that smells is the micron 78 resistor on the heat sink. I will try to change that too. Honestly...lot of fun :(
|
Re: Tuning..again - Transposition gate zeroing?
The issue you're describing is rather strange. It only impacts master board I-4. But what is really weird is that it only happens when one of the last four preset selectors is pressed.
The trigger wire is certainly not the problem since the other presets work with this board.
Did you try modifying the panel settings while playing board I-4, just to see if it's bound to a specific parameter of the synthesis line ? The first idea that comes to mind is that you inadvertently modified an other variable resistor while applying the tuning procedure. You could also make a thorough comparison with board I-3 for instance.
|
|
|
Which "resonator" is this?
|
Here is another vid I made the other day. This time the 'Resonator' is on my recently repaired and 'arpeggiating' Korg Polysix with the CS80 doing lead-line.
Cheerz,
Tom
|
Re: Another one of my videos...
Hi Phil,
It is a: Freeform Analogue Technologies (FAT) THC-00 "Resinator"
Cheers, Tom
|
Re: Tuning..again - Transposition gate zeroing?
Thanks Joachim. I have managed to make the adjustments on the KAS a little better (still few cents out tough..) Now I have finished the complete tuning procedure and it seems to be pretty neat. I have found out that after completing the step 8 it is important do repeat the 7 and 8 again until it?s within the specs. After finishing the procedure a strange problem manifested itself...the board 4 channel 1 is mute ?at the panel, memory 1,2 and funky 3 buttons (it is like there is no trigger). Other presets work fine on it but it seems to be louder that the others..
|
Re: Tuning..again - Transposition gate zeroing?
step 1 - ok 4,00VThis is the expected voltage for C6.
step 2 - 125,7mV instead 125,0mV potentiometer to the max
This means that when you play C1, the pitch will be too high (roughly by 10 cents).
The manual says you should not go above 0.1 %, that is 125,12 mV (corresponding roughly to 1.4 cents).
If this variable resistor is damaged, you should perhaps consider changing it.
You could first check it: once unsoldered, its total resistance should be 20 ohms.
step 3 - 125,1mV instead 125,1mV
If you meant 125,1 mV instead of 125,0 mV, that's within the tolerances.
step 4 - 131,4mV instead 132,4mV potentiometer to the max
This is 15 cents too low.
Increasing the voltage on TU to around 4,04V helps for step 4 but the others go south. That's obviously not the way to go ;-) Keep TU to 4 V.
Anyway, fix the issues in the order of the steps.
|
Re: Tuning..again - Transposition gate zeroing?
Thank you Joachim for the complete and patient answer! You?re always there for us. I am aware of all the steps but I never did the 7 (transposition gate zeroing). It seems that all my M boards are off (none of them are close to zero).
My PSU is calibrated and solid, but I have problems getting accurate voltages on the KAS board (page 3).. step 1 -ok 4,00V step 2 - 125,7mV instead 125,0mV potentiometer to the max step 3 - ?125,1mV instead 125,1mV step 4 - 131,4mV instead 132,4mV potentiometer to the max Increasing the voltage on TU to around 4,04V helps for step 4 but the others go south. step 5 and 6 ok.
|
Re: Tuning..again - Transposition gate zeroing?
Hi,
1. What does really the transposition gate zeroing do? It does precisely what its name says: it insures the voltage used? to determine the frequency of the VCO is zero, or reasonably close to zero.
?? Can it effect tuning between two channels on one voice? If you modify VR1 without modifying anything else, yes. But tuning the M-board requires several settings which should all be done. (As explained on page 5 of the CS-80 adjustment procedure)
2.
?It says I should measure the voltage between CP6 and EK terminals.
Does that mean I should put a minus probe on CP6 and plus on EK ?(or
vice-versa)? It does not matter. Since the measure will vary around 0, you should expect negative as well as positive values, depending on the setting of each variable resistor. With a DVM this should not be a problem.
3.
It says I should read .120mV. at 2?.
Not exactly: it says you should set the voltage to 0, plus or minus at most 0.120 mv. The closest to 0 the better.
My DVM is very basic and the max
resolution I get is 200m. Depending on the board i read 0.28 to 0.40! I
have no clue is that normal every board is way off? The idea is to set VR1 so that you measure a voltage between CP6 and EK as close to 0 as possible. But remember that the tuning of a board is a process that requires all steps 7 to 12 to be performed.
Joachim
|
Re: Another one of my videos...
Very nice. And what model & brand is that?three band Resonator module ?
On 4 February 2017 at 23:29, noddyspuncture@... [yamahacs80] <yamahacs80@...> wrote:
?
Hi folks,
Here is one I made today. I put my CS80's string presets through a 3 band resonator. Hope you like...:)
Cheers, Tom
|
Tuning..again - Transposition gate zeroing?
So I am chasing the dragon yet again... What I am after is this steady ultraslow sweep between the channels and some of them are banging to quickly. I have never adjusted transposition gate zeroing before and here is my question (I?d like to know do I read the manual right..).? 1. What does really the transposition gate zeroing do? Can it effect tuning between two channels on one voice? 2. ?It says I should measure the voltage between CP6 and EK terminals. Does that mean I should put a minus probe on CP6 and plus on EK ?(or vice-versa)? 3. It says I should read .120mV. at 2?. My DVM is very basic and the max resolution I get is 200m. Depending on the board i read 0.28 to 0.40! I have no clue is that normal every board is way off?
Thanks in advance for your patient answers.
|
Re: Another one of my videos...
thanks... I should fix my channel 1 / M1 voice card one of these days.... sigh
toggle quoted message
Show quoted text
? Hi folks,
Here is one I made today. I put my CS80's string presets through a 3 band resonator. Hope you like...:)
Cheers, Tom
|
Another one of my videos...
Hi folks,
Here is one I made today. I put my CS80's string presets through a 3 band resonator. Hope you like...:)
Cheers, Tom
|
The NICE's 'Country Pie' on CS80...!
Here is my latest...:) Cheerz, Tom?
| | | | | | I had actually worked all this out many years ago... but then I just completely left it and only just revisited it recently. Funny how you forget... I had to... | | | | Preview by Yahoo | | |
|
Re: Clean CS-80 Overall Circuit Diagram
Whoa! That is incredible background info. So if we've never replaced those caps, would our?CS-80s have these minerals of conflict? If so, it would be my only keyboard that has a scandalous reputation, ha!?
Well, I have no background history on it when Roy Orbison owned it, Who knows the things that might've gone on around it when he had it in his studio!
toggle quoted message
Show quoted text
On Jan 9, 2017, at 7:13 PM, David Rogoff david@... [yamahacs80] < yamahacs80@...> wrote:
?
Speaking of replacing caps. ?For years, I’ve replaced tantalums whenever working on old gear because of their problems like exploding. ?There’s one-per-note on the TSB boards. ?I just read in ?that there’s another important reason:
I had no idea they were connected with conflict minerals!
And I also didn’t realized what this did to the price when companies switched to non-conflict sources a few years ago:
?David
Hi Tom,Thanks for pointing these issues.You're right concerning the 100uF capacitors. There are 4 decoupling capacitors; two between ground and +15V, and two between ground and -15V. I changed the 33uF one near the IC1 to a 100uF, and I added a new 100uF one near the IC3 (which corresponds roughly to where it really lies on the board).As for the 4.7uF capacitors, those on my boards are in compliance with the schematics. Two are polarized and are yet other decoupling capacitors (between -15V and +15V, this time). The other two are non polarized and are located near IC8 and IC9.I updated the overall circuit diagram to reflect these. It is available?.I also put in the photo gallery of the CS80 group a copy of the M-board schematic (p44 of the service manual) where I highlighted the 42 capacitors, and also fixed a couple of missing components and a label inversion (fixed in red). You can find it?.Joachim?
|
pyjamagroove