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Kurzweil K2000 Query

Kurzweil K2000 Query

2009-07-13 by soundcrafter

I'm taking a look at a K2000 for a friend. 

We were playing, and suddenly the K2000 lost volume...  It wasn't a dramatic loss, the patch was still audible, but there was *definitely* a loss in volume.  The patch wasn't changed or edited, mixer settings weren't changed, etc.  It just got quieter all of a sudden.

At first we thought it might be some sort of mechanical failure in the
output jack... A solder joint on the way out, or a worn out center
connection.  However, that doesn't seem to be the case.  The problem
persists on the L, R, and Headphone jacks, and on different patches as well.

There's no noticeable difference in the audio quality. However, as time has passed we've noticed the volume loss seems to be slowly getting worse.  I'm thinking maybe something is going out in the final output stages, but I've no idea where to look.

A user on another list suggested checking the batteries, but there are no batteries in this particular unit, and there haven't been for quite some time.  The owner just uses it for the stock sounds, and as a controller.

Anyone have any thoughts?  Suggestions? I'm going to see if I can google up a schematic, any pointers there would be welcome also.

Thanks for any insights you may have...

DTK

Re: [vintagesynthrepair] Kurzweil K2000 Query

2009-07-14 by Stephen Jones

It is not uncommon for failures of the J109 FET's on each output of the K2000 to fail. They are there to prevent turn-on thumps through your speakers.

You can also put the synth into diagnostic mode and run the relevant tests. Or, you can save your patches to floppy and hard reset the machine as a first step in case it is a software issue..

Show quoted textHide quoted text

From: soundcrafter
To: vintagesynthrepair@yahoogroups.com
Sent: Tuesday, July 14, 2009 9:16:43 AM
Subject: [vintagesynthrepair] Kurzweil K2000 Query

I'm taking a look at a K2000 for a friend.

We were playing, and suddenly the K2000 lost volume... It wasn't a dramatic loss, the patch was still audible, but there was *definitely* a loss in volume. The patch wasn't changed or edited, mixer settings weren't changed, etc. It just got quieter all of a sudden.

At first we thought it might be some sort of mechanical failure in the
output jack... A solder joint on the way out, or a worn out center
connection. However, that doesn't seem to be the case. The problem
persists on the L, R, and Headphone jacks, and on different patches as well.

There's no noticeable difference in the audio quality. However, as time has passed we've noticed the volume loss seems to be slowly getting worse. I'm thinking maybe something is going out in the final output stages, but I've no idea where to look.

A user on another list suggested checking the batteries, but there are no batteries in this particular unit, and there haven't been for quite some time. The owner just uses it for the stock sounds, and as a controller.

Anyone have any thoughts? Suggestions? I'm going to see if I can google up a schematic, any pointers there would be welcome also.

Thanks for any insights you may have...

DTK

Re: Kurzweil K2000 Query

2009-07-28 by soundcrafter

Some others had suggested this as well, so I think I will start my checks here.  

There is one of these on each output?  If so, it seems unlikely they would both fail at the same time, in the same way.  Is there some common control circuitry?  If so, what should I be looking for?  Voltage, or lack thereof, on one of the legs of the FET?

Any help is appreciated, as I'm flying blind without the schematics

DTK

Show quoted textHide quoted text

>
> It is not uncommon for failures of the J109 FET's on each output of the K2000 to fail. They are there to prevent turn-on thumps through your speakers.
> You can also put the synth into diagnostic mode and run the relevant tests. Or, you can save your patches to floppy and hard reset the machine as a first step in case it is a software issue.
>

Re: [vintagesynthrepair] Re: Kurzweil K2000 Query

2009-07-28 by GB

If memory serves you can even remove them. Like an appendix or tonsils.

GB

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----- Original Message -----

From: soundcrafter

To: vintagesynthrepair@yahoogroups.com

Sent: Monday, July 27, 2009 7:13 PM

Subject: [vintagesynthrepair] Re: Kurzweil K2000 Query

Some others had suggested this as well, so I think I will start my checks here.

There is one of these on each output? If so, it seems unlikely they would both fail at the same time, in the same way. Is there some common control circuitry? If so, what should I be looking for? Voltage, or lack thereof, on one of the legs of the FET?

Any help is appreciated, as I'm flying blind without the schematics

DTK

>
> It is not uncommon for failures of the J109 FET's on each output of the K2000 to fail. They are there to prevent turn-on thumps through your speakers.
> You can also put the synth into diagnostic mode and run the relevant tests. Or, you can save your patches to floppy and hard reset the machine as a first step in case it is a software issue.
>

Re: Kurzweil K2000 Query

2009-07-28 by soundcrafter

Interesting... can anyone confirm this?  Or would it be a bad idea?

Show quoted textHide quoted text

> If memory serves you can even remove them.  Like an appendix or tonsils.
> 
> GB
> 
>   ----- Original Message ----- 
>   From: soundcrafter 
>   To: vintagesynthrepair@yahoogroups.com 
>   Sent: Monday, July 27, 2009 7:13 PM
>   Subject: [vintagesynthrepair] Re: Kurzweil K2000 Query
> 
> 
>     Some others had suggested this as well, so I think I will start my checks here. 
> 
>   There is one of these on each output? If so, it seems unlikely they would both fail at the same time, in the same way. Is there some common control circuitry? If so, what should I be looking for? Voltage, or lack thereof, on one of the legs of the FET?
> 
>   Any help is appreciated, as I'm flying blind without the schematics
> 
>   DTK
> 
>   >
>   > It is not uncommon for failures of the J109 FET's on each output of the K2000 to fail. They are there to prevent turn-on thumps through your speakers.
>   > You can also put the synth into diagnostic mode and run the relevant tests. Or, you can save your patches to floppy and hard reset the machine as a first step in case it is a software issue.
>   >
>

Re: [vintagesynthrepair] Re: Kurzweil K2000 Query

2009-07-28 by Stephen Jones

They do tend to fail in groups, usually if there is a floating earth potential in the equipment that you connect the K2000 to via the audio jack. It is a bit if a job to get the board out and replace the FET's, most people just clip them off altogether and put up with turn-on thumps.

________________________________
From: soundcrafter <aurastar@...>
To: vintagesynthrepair@yahoogroups.com
Sent: Tuesday, July 28, 2009 2:12:31 PM
Subject: [vintagesynthrepair] Re: Kurzweil K2000 Query

Interesting. .. can anyone confirm this?  Or would it be a bad idea?

Show quoted textHide quoted text

> If memory serves you can even remove them.  Like an appendix or tonsils.
> 
> GB
> 
>   ----- Original Message ----- 
>   From: soundcrafter 
>   To: vintagesynthrepair@ yahoogroups. com 
>   Sent: Monday, July 27, 2009 7:13 PM
>   Subject: [vintagesynthrepair ] Re: Kurzweil K2000 Query
> 
> 
>     Some others had suggested this as well, so I think I will start my checks here. 
> 
>   There is one of these on each output? If so, it seems unlikely they would both fail at the same time, in the same way. Is there some common control circuitry? If so, what should I be looking for? Voltage, or lack thereof, on one of the legs of the FET?
> 
>   Any help is appreciated, as I'm flying blind without the schematics
> 
>   DTK
> 
>   >
>   > It is not uncommon for failures of the J109 FET's on each output of the K2000 to fail. They are there to prevent turn-on thumps through your speakers.
>   > You can also put the synth into diagnostic mode and run the relevant tests. Or, you can save your patches to floppy and hard reset the machine as a first step in case it is a software issue.
>   >
>

Re: Kurzweil K2000 Query

2009-08-02 by soundcrafter

Alright, I got a chance to try this out, and it seems to have made things better, but I'm not sure its completely fixed just yet.

I clipped the FETs located behind the L and R jacks.  The output definitely got louder from both jacks, and the headphone jack, but it seems (and I've now confirmed with my mixer) that the L output is considerably quieter than R.  I *may* have heard a bit of crackling there also, I'm not sure... I have to play a bit more and see.

Anyway, it seems like progress, which is good! Thanks for the assistance... Any suggestions going forward?

Thanks

Show quoted textHide quoted text

> It is not uncommon for failures of the J109 FET's on each output of the K2000 to fail. They are there to prevent turn-on thumps through your speakers.
> You can also put the synth into diagnostic mode and run the relevant tests. Or, you can save your patches to floppy and hard reset the machine as a first step in case it is a software issue.
> 
> 
> ________________________________
> From: soundcrafter <aurastar@...>
> To: vintagesynthrepair@yahoogroups.com
> Sent: Tuesday, July 14, 2009 9:16:43 AM
> Subject: [vintagesynthrepair] Kurzweil K2000 Query
> 
> 
> 
> 
> 
> I'm taking a look at a K2000 for a friend. 
> 
> We were playing, and suddenly the K2000 lost volume...  It wasn't a dramatic loss, the patch was still audible, but there was *definitely* a loss in volume.  The patch wasn't changed or edited, mixer settings weren't changed, etc.  It just got quieter all of a sudden.
>

Re: [vintagesynthrepair] Re: Kurzweil K2000 Query

2009-08-07 by Stephen Jones

From memory I think that it is normal for one output to be louder than the other if you only insert one plug, as there is a switching jack to sum one of the outputs to mono of both channels, so don't try and test by putting a jack in one side at a time, check by connecting BOTH outputs to a mixer and see if the level is the same between both channels, if so then the machine is fine. 

________________________________
From: soundcrafter <aurastar@...>
To: vintagesynthrepair@yahoogroups.com
Sent: Sunday, August 2, 2009 2:37:00 PM
Subject: [vintagesynthrepair] Re: Kurzweil K2000 Query

Alright, I got a chance to try this out, and it seems to have made things better, but I'm not sure its completely fixed just yet.

I clipped the FETs located behind the L and R jacks.  The output definitely got louder from both jacks, and the headphone jack, but it seems (and I've now confirmed with my mixer) that the L output is considerably quieter than R.  I *may* have heard a bit of crackling there also, I'm not sure... I have to play a bit more and see.

Anyway, it seems like progress, which is good! Thanks for the assistance.. . Any suggestions going forward?

Thanks

Show quoted textHide quoted text

> It is not uncommon for failures of the J109 FET's on each output of the K2000 to fail. They are there to prevent turn-on thumps through your speakers.
> You can also put the synth into diagnostic mode and run the relevant tests. Or, you can save your patches to floppy and hard reset the machine as a first step in case it is a software issue.
> 
> 
> ____________ _________ _________ __
> From: soundcrafter <aurastar@.. .>
> To: vintagesynthrepair@ yahoogroups. com
> Sent: Tuesday, July 14, 2009 9:16:43 AM
> Subject: [vintagesynthrepair ] Kurzweil K2000 Query
> 
> 
> 
> 
> 
> I'm taking a look at a K2000 for a friend. 
> 
> We were playing, and suddenly the K2000 lost volume...  It wasn't a dramatic loss, the patch was still audible, but there was *definitely* a loss in volume.  The patch wasn't changed or edited, mixer settings weren't changed, etc.  It just got quieter all of a sudden.
>