The No.1 Website for Pro Audio
 Search This Thread  Search This Forum  Search Reviews  Search Gear Database  Search Synths for sale  Search Gearslutz Go Advanced
Need advice on calibration Keyboard Synthesizers
Old 8th September 2011
  #1
Gear Nut
 
OL303's Avatar
 

Need advice on calibration

Hi, I have a JP6 and a Juno-60, they seem to need calibration, I checked the service manual and it says I need a volt meter and an oscilloscope, I got the multimeter, but no scope. I never used a scope so can someone tell me what kind of machine will do the work? I saw they can be really expensive and I ain't got the cash, will the software scope be good?
Please let me know what I need.

Thanks,
OL.
Old 8th September 2011
  #2
Gear Guru
 
Yoozer's Avatar
Are you sure you want to take on calibration if you've never used a scope?

Scopes -can- be expensive; older CRT ones which are bulky and only do waveform display (no signal analysis at stupidly high frequencies) aren't that expensive, however. Though it may be hard to get the probes if they didn't come with the unit.

For what you want to do you don't need accuracy in the MHz levels, so software scopes should do the job just fine, too.
Old 8th September 2011
  #3
Gear Nut
 
OL303's Avatar
 

Ok great, I am willing to take the risk. My guess is it shouldn't too hard,
So what's the best software scope?
I have an iPhone too if that matters.

Thanks.
OL
Old 8th September 2011
  #4
Lives for gear
Just out of interest, what on your synths are out of calibration?

Personally, I'd take a hardware scope over computer one any day.

Hands on and immediate.. (where have I heard those terms being used in reference to analogue vs digital software??)

See if you can borrow one? It does not need to be fancy.. 1Mhz or more.
I'd also learn how to use it, and calibrate it..

Also, many of the important synth calibrations don't need a scope, so hence my first question.
Old 8th September 2011
  #5
Gear Nut
 
OL303's Avatar
 

Well, the jp6 is way out of tune, and I never had it calibrated before hence why I want to give it the full procedure. The Juno too never been calibrated, I suspect the Lfo is not at it's correct rate and maybe the resonance is too strong. I have seen people say it can improve the sound if you go through calibration.
I admit I know very little about electronics theory but I don't see why I wouldn't be able to DIY it If I follow the service manual instructions.
All I need to do is find the right scope and learn enough to know what the SM says to do. Do you see any way I can get my self in trouble or damage the synths?
Old 8th September 2011
  #6
nms
Lives for gear
 
nms's Avatar
For most things you can get away without the scope. In one or two places you can use a VST scope. Get your hands on a multimeter and do all you can with that.
Old 8th September 2011
  #7
Gear Nut
 
OL303's Avatar
 

How does one use the VST scope for checking audio signal? I thought you need a probe or something to touch the test points, is there a different way yo do it? Sorry for being so uneducated on this matter.
Old 8th September 2011
  #8
Gear Head
 
Roboticefx's Avatar
 

If you're going to do a proper calibration, you'll need to get a calibrated o-scope. HP and Agilent make very good ones. If you want to do a fly-by-night calibration, use whatever you want. If you don't want to buy the right test equipment and still want the job done properly, it's best to just pay somebody else to do it for you.

It's ok that you want to do some DIY, but I don't see why you'd want to jump in and do this when there are others who have gone to school to study electronics and have years of experience. If you're looking at calibrating the synth because something sounds wrong, it might not be as easy as tweaking a few variable resistors. There could be a component that is either broken or performing inadequately that you might miss. An experienced person could spot it and save you time, or even identify a future problem. There is much more to troubleshooting than simply following steps in a service manual. That's when theory and experience come into play.

On the bright side, I seriously doubt that you'll damage anything on the synth unless you're completely careless and short something. The most common problems are going to be user error...whether it's a calculation error, or you simply eye the wrong component and tweak it accidentally and don't know what value to return it to. Again if it's a simple cal, it shouldn't give you too much trouble. Happy hunting.
Old 8th September 2011
  #9
Lives for gear
 
Dave Peck's Avatar
 

If you are only trying to calibrate the V/oct oscillator pitch tracking you don't need any test equipment. A second synth that can drone on one pitch while you play octaves on the synth you are calibrating will work fine. Set them to play the same pitch, play an octave up on the synth you are calibrating, if it's sharp or flat you adjust the cal trim pot a bit, then play the unison note again and retune them using the front panel fine tune, repeat until they track correctly. I calibrate all my analog oscs this way a couple of times a year and it's pretty easy.
Old 8th September 2011
  #10
Gear Head
 

I'd search for for a 2-channel B&K oscilloscope on eBay. You should be able to pick one up for under $100 shipped with a return policy. It will be enough to get your synth within the specs you need it to be. Very handy to have around...
Old 9th September 2011
  #11
Gear Nut
 
OL303's Avatar
 

I'll check out eBay, 100$ is a good investment. Anything I need to make sure before ordering?
Old 9th September 2011
  #12
Lives for gear
 
oldgearguy's Avatar
 

Quote:
Originally Posted by OL303 View Post
Well, the jp6 is way out of tune, and I never had it calibrated before hence why I want to give it the full procedure. The Juno too never been calibrated, I suspect the Lfo is not at it's correct rate and maybe the resonance is too strong. I have seen people say it can improve the sound if you go through calibration.
I admit I know very little about electronics theory but I don't see why I wouldn't be able to DIY it If I follow the service manual instructions.
All I need to do is find the right scope and learn enough to know what the SM says to do. Do you see any way I can get my self in trouble or damage the synths?
Note that every JP-6 I've had needs to have the 'Tune' button pressed after power on, otherwise it sounds way off. Even after a full calibration, for some reason, the JP-6 does not power up anywhere close to in tune for all 6 voices.

Does that match other JP-6 owner's findings?
Old 9th September 2011
  #13
Gear Nut
 
OL303's Avatar
 

Mine is out of tune generally, and much worse than what the tune button range can fix. Thats why I want to go through the calibration.
It is known though that the analog chips of the jp6 get out of tune a little and need to warm up before the get to be steady, thats the reason they put the tune button there from the start.
Old 9th September 2011
  #14
Lives for gear
 
dougt's Avatar
 

To calibrate the VCOs you can just use your ears, no need for a scope. You should have a voltmeter to adjust the power supply voltages though.
Old 10th September 2011
  #15
Gear Nut
 
OL303's Avatar
 

Quote:
Originally Posted by dougt View Post
To calibrate the VCOs you can just use your ears, no need for a scope. You should have a voltmeter to adjust the power supply voltages though.
How do you do that?
I thought that if you change this parameter you might influence some other measurements out of their axis, I remember reading that in order to get it right you need do go through the process by a specific order. Am I wrong here?
Old 10th September 2011
  #16
Gear Addict
 
JEBEQ's Avatar
 

I have used this software Oscilloscope many times and it has worked for me. It's worth a shot.
Oh, and it's free

Soundcard Scope



Old 10th September 2011
  #17
Lives for gear
 

Quote:
Originally Posted by OL303 View Post
How do you do that?
I thought that if you change this parameter you might influence some other measurements out of their axis, I remember reading that in order to get it right you need do go through the process by a specific order. Am I wrong here?

yes and no...

the first thing you should tune is the power supply rails if they have that ability.

after that the oscs should be done dry starting with osc 1 and track the keyboard properly, then move on to 2 and make sure it also tracks correctly and in tune with 1 and all voices are the same tune if they have individual tuning capabilities.

once the oscs are tuned you can go in pretty much any order for the lfos and envelopes and filters and amp stages.

and no you won't need a scope to tune it. it just makes the tuning process faster and more accurate, and if you have a problem with the waveshapes you can see it easily. other than for actual troubleshooting of real issues you won't need a scope. tuning it can be done with a guitar tuner, your ears and another stable tuned source, a software scope etc... any of those would work to tune it if it tracks the keybed properly. if you have a voice that's off and won't go no matter what or drifts in and out then you have an issue that will be beyond you and need to see a tech at that point.
Old 10th September 2011
  #18
Gear Nut
 
OL303's Avatar
 

Quote:
Originally Posted by W-W-Int View Post
yes and no...

the first thing you should tune is the power supply rails if they have that ability.

after that the oscs should be done dry starting with osc 1 and track the keyboard properly, then move on to 2 and make sure it also tracks correctly and in tune with 1 and all voices are the same tune if they have individual tuning capabilities.

once the oscs are tuned you can go in pretty much any order for the lfos and envelopes and filters and amp stages.

and no you won't need a scope to tune it. it just makes the tuning process faster and more accurate, and if you have a problem with the waveshapes you can see it easily. other than for actual troubleshooting of real issues you won't need a scope. tuning it can be done with a guitar tuner, your ears and another stable tuned source, a software scope etc... any of those would work to tune it if it tracks the keybed properly. if you have a voice that's off and won't go no matter what or drifts in and out then you have an issue that will be beyond you and need to see a tech at that point.
This info is very helpful, I think I get it more now.
All I need to do is learn how to measure the power suply, never did it before so i hope it's not to chalanging, I got myself a decent digital multimeter.
can you give me a simple guidline on how to do it or is it to much to ask from this forum?
Or if someone has a good video on how to do it please link it here.
Thanks.
Old 10th September 2011
  #19
Gear Head
 
Roboticefx's Avatar
 

Taking a voltage check is very easy. Your red lead will be your positive, and black will be your ground. If you have a service manual with schematics it will be very easy to check voltages. Odds are, you will have a number of test points on the circuit board to make it easier. You will simply ground the black lead, and touch the test point you want to check. Everything is rectified from VAC to VDC in the circuit, so you really shouldn't be doing any AC measurements. Your multimeter will probably have ranges like mVDC, VDC, etc. When you test a voltage in either range, just switch to that range, and test it. It's very easy. Happy Hunting.
Old 10th September 2011
  #20
Gear Nut
 
OL303's Avatar
 

Quote:
Originally Posted by Roboticefx View Post
Taking a voltage check is very easy. Your red lead will be your positive, and black will be your ground. If you have a service manual with schematics it will be very easy to check voltages. Odds are, you will have a number of test points on the circuit board to make it easier. You will simply ground the black lead, and touch the test point you want to check. Everything is rectified from VAC to VDC in the circuit, so you really shouldn't be doing any AC measurements. Your multimeter will probably have ranges like mVDC, VDC, etc. When you test a voltage in either range, just switch to that range, and test it. It's very easy. Happy Hunting.

OK so lets say i start with this Yamaha CS10, I got the VCO Scematic here, it doesn't say anything about the ground point, so where do i find it here?
Also the TP are not marked on the PCB, I guess it's these litle silver squers spread all over the PCB but they are unmarked: and
Old 11th September 2011
  #21
Gear Head
 
Roboticefx's Avatar
 

The ground symbols in that schematic are marked as chassis ground, judging by all the ones I see. You can clip your black lead to the chassis of the synth. Normally a screw post with a wire leading from the circuit board will do. If it's not clean or a good connection you'll get improper readings. The best choice is to look at the schematic, and attach it to a ground that you can see there. Closer to the circuit will give you a better measurement.

As for the test points, sometimes they're solder pads, eyelets, or posts. If you can't figure out which test point is which, you can look at the schematic and follow it to the nearest point. It's best to follow it to a component where you can identify which side you are connecting. For example, you normally won't know what side of a resistor to check unless you chase the solder run to another component. However, an IC chip is much easier to follow. So, for example, I saw that they mention TP1. If you look at the schematic, this is electrically the same point as IC1 pin 25. Test that pin if you can't find the TP.
Old 11th September 2011
  #22
Gear Nut
 
OL303's Avatar
 

Ok I am going to try it tomorrow, I think I am getting the hang of it, I'll post the test results as soon as I get it right.
ThNks my friends.
Old 1st November 2011
  #23
Lives for gear
Sorry to bump a dated thread but I'm wondering if OL303 had positive results. I'm in about the same boat he is and I want to try a little tune up on two of my old keyboards. I have a JP6 and Polysix that need the voices tuned for pitch, at the very least.

Am I doing myself a disservice if I DIY and only tune the voices? From reading this thread that sounds like a relatively painless process. I'm not sure where I would go to have something professionally serviced in my area...

Thanks for any advice!
Old 7th November 2011
  #24
Gear Nut
 
OL303's Avatar
 

Quote:
Originally Posted by slippast View Post
Sorry to bump a dated thread but I'm wondering if OL303 had positive results. I'm in about the same boat he is and I want to try a little tune up on two of my old keyboards. I have a JP6 and Polysix that need the voices tuned for pitch, at the very least.

Am I doing myself a disservice if I DIY and only tune the voices? From reading this thread that sounds like a relatively painless process. I'm not sure where I would go to have something professionally serviced in my area...

Thanks for any advice!
Hi,
I am sorry but I did not get to mess with the JP6 yet.
I hope I will get to it this week. I'll let you know the results when It's done.
Meanwhile you can describe your problem In a more detailed way.
Old 7th November 2011
  #25
Lives for gear
 
ttown23's Avatar
I don't know, but I'm all for DIY calibration. It's how I learned to maintain all of my analogue synths, a rather lengthy list of 15 or so.

... and I don't own a scope, never had the need for one, just use my multimeter and a service manual, which is good for most things; and use your ears for OSC tuning (go for zero beats and you're good to go...).

Good luck, and welcome to the world of DIY analogue keyboard maintenance
Old 7th November 2011
  #26
Lives for gear
 

Quote:
Originally Posted by nms View Post
For most things you can get away without the scope. In one or two places you can use a VST scope. Get your hands on a multimeter and do all you can with that.
there is no jupiter 6 callibration without a scope..

why you dont leave that to people that are experianced with that?

you know..the setup procedure by roland is just the plain minimal standard setting. The jupiters have left roland with a way finer tuning than just the basic setup. the tollerances roland mentions in their setup are ment to be dealt with by ear.
Old 8th November 2011
  #27
Lives for gear
Quote:
Originally Posted by OL303 View Post
Hi,
I am sorry but I did not get to mess with the JP6 yet.
I hope I will get to it this week. I'll let you know the results when It's done.
Meanwhile you can describe your problem In a more detailed way.
Well, I think my problems are the same as yours; not really problems. The voices are a little out of tune. Not enough to be a major distraction, but if my guitar were out this much every time I played it it would drive me nuts. I'm more forgiving of a synth because the tone typically has a lot of modulations going on and the oscillators are usually intentionally detained a little.

Still, each voice in the JP6 and the Polysix is a little out, landing a little bit to either side of the desired pitch. Perhaps that's just part of the magic and I should leave it alone?
Old 27th August 2012
  #28
Here for the gear
 

Hello and sorry for bumping such an old thread. I am currently pitch-calibrating a Kawai 100F for the first time and I was wondering what pots I should use. There is:
a Tune pot.
"+10.00v" pot,
Range Slope pot,
K. CV Adj,
Key Slope Adj
and finally a Filter ADJ.

There is also an unmarked Pot, bigger than the others next to the External Audio Input cable on the PCB ( I guess a volume trimpot for the external audio? it was turned to max)

Any hints?

thankyou very much.
Old 27th August 2012
  #29
Here for the gear
 

nm, I managed by using the +10.00v and K CV adj together with the tuner on the frontboard. phew thanks anyways!
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump