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Clone - MG always on by default

Clone - MG always on by default

2014-10-11 by f115@rocketmail.com

Hey everyone!

Well at long last I revisited my KLM clone build and finally got it up and running... almost!

Calibration went smoothly but I have one last piece to tackle. The MG seems to be on in some way no matter what patch is chosen. I uploaded the Factory A banks so that's the point of reference. Patch A1 should just be a clean brass with a delayed MG. I even swapped out T1/Q1 with an original from my old board but that didn't seem to make any difference.

I scoured the message archive but didn't find anything. I thought that was a fairly common issue for all Polysixes. Perhaps I was mistaken.

Thanks!


Re: [PolySix] Clone - MG always on by default

2014-10-11 by Chris Horsten

A Polysix clone is a great idea! Do you have pictures? I've wondered why Korg doesn't re-release it, clearly it's become a desirable KB again.

Do you have any plans to release a plans set? 

Regards
C

Sent from my iPlane. 

On Oct 10, 2014, at 8:46 PM, "f115@rocketmail.com [PolySix]" <PolySix@yahoogroups.com> wrote:

 

Hey everyone!

Well at long last I revisited my KLM clone build and finally got it up and running... almost!

Calibration went smoothly but I have one last piece to tackle. The MG seems to be on in some way no matter what patch is chosen. I uploaded the Factory A banks so that's the point of reference. Patch A1 should just be a clean brass with a delayed MG. I even swapped out T1/Q1 with an original from my old board but that didn't seem to make any difference.

I scoured the message archive but didn't find anything. I thought that was a fairly common issue for all Polysixes. Perhaps I was mistaken.

Thanks!


Re: [PolySix] Clone - MG always on by default

2014-10-11 by Dennis Matana

Dude he is talking about the KLM376 Clone board which replaces the old KLM board....not a total clone of the P6 :)
 

 
                           


On Saturday, October 11, 2014 2:48 PM, "Chris Horsten cphorsten@yahoo.ca [PolySix]" <PolySix@yahoogroups.com> wrote:


 
A Polysix clone is a great idea! Do you have pictures? I've wondered why Korg doesn't re-release it, clearly it's become a desirable KB again.

Do you have any plans to release a plans set? 

Regards
C

Sent from my iPlane. 

On Oct 10, 2014, at 8:46 PM, "f115@rocketmail.com [PolySix]" <PolySix@yahoogroups.com> wrote:

 
Hey everyone!

Well at long last I revisited my KLM clone build and finally got it up and running... almost!

Calibration went smoothly but I have one last piece to tackle. The MG seems to be on in some way no matter what patch is chosen. I uploaded the Factory A banks so that's the point of reference. Patch A1 should just be a clean brass with a delayed MG. I even swapped out T1/Q1 with an original from my old board but that didn't seem to make any difference.

I scoured the message archive but didn't find anything. I thought that was a fairly common issue for all Polysixes. Perhaps I was mistaken.

Thanks!




Re: [PolySix] Clone - MG always on by default

2014-10-11 by Chris Horsten

Lol. Thanks - leapt too soon! Wishful thinking.... Still looking to add one to my "studio" if anyone has one for sale.

C

From: "Dennis Matana denderdj@yahoo.com [PolySix]" <PolySix@yahoogroups.com>
To: "PolySix@yahoogroups.com" <PolySix@yahoogroups.com>
Sent: Saturday, October 11, 2014 10:08 AM
Subject: Re: [PolySix] Clone - MG always on by default

 
Dude he is talking about the KLM376 Clone board which replaces the old KLM board....not a total clone of the P6 :)
 

 
                           


On Saturday, October 11, 2014 2:48 PM, "Chris Horsten cphorsten@yahoo.ca [PolySix]" <PolySix@yahoogroups.com> wrote:


 
A Polysix clone is a great idea! Do you have pictures? I've wondered why Korg doesn't re-release it, clearly it's become a desirable KB again.

Do you have any plans to release a plans set? 

Regards
C

Sent from my iPlane. 

On Oct 10, 2014, at 8:46 PM, "f115@rocketmail.com [PolySix]" <PolySix@yahoogroups.com> wrote:

 
Hey everyone!

Well at long last I revisited my KLM clone build and finally got it up and running... almost!

Calibration went smoothly but I have one last piece to tackle. The MG seems to be on in some way no matter what patch is chosen. I uploaded the Factory A banks so that's the point of reference. Patch A1 should just be a clean brass with a delayed MG. I even swapped out T1/Q1 with an original from my old board but that didn't seem to make any difference.

I scoured the message archive but didn't find anything. I thought that was a fairly common issue for all Polysixes. Perhaps I was mistaken.

Thanks!






Re: [PolySix] Clone - MG always on by default

2014-10-11 by Jed Jorgensen

Did you fix the two pcb mistakes described here: https://sites.google.com/site/jedjorgensen/klm367a/images/pcb-bugs-errors

The second one is the mg delay...

On Oct 10, 2014 5:46 PM, "f115@rocketmail.com [PolySix]" <PolySix@yahoogroups.com> wrote:
 

Hey everyone!

Well at long last I revisited my KLM clone build and finally got it up and running... almost!

Calibration went smoothly but I have one last piece to tackle. The MG seems to be on in some way no matter what patch is chosen. I uploaded the Factory A banks so that's the point of reference. Patch A1 should just be a clean brass with a delayed MG. I even swapped out T1/Q1 with an original from my old board but that didn't seem to make any difference.

I scoured the message archive but didn't find anything. I thought that was a fairly common issue for all Polysixes. Perhaps I was mistaken.

Thanks!


Re: [PolySix] Re: Clone - MG always on by default

2014-10-14 by f115@rocketmail.com

My rebuild followed the BOM or pulled an original so all the transistors are matched up and should be on par. If there's anything specific that I should check let me know. Cheers!

Re: [PolySix] Re: Clone - MG always on by default

2014-10-15 by Jed Jorgensen

If you used original transistors some of the points could be different than for the new replacements. Check the transistors you used and report back.

On Oct 14, 2014 4:42 PM, "f115@rocketmail.com [PolySix]" <PolySix@yahoogroups.com> wrote:
 

My rebuild followed the BOM or pulled an original so all the transistors are matched up and should be on par. If there's anything specific that I should check let me know. Cheers!

Re: [PolySix] Re: Clone - MG always on by default

2014-10-15 by f115@rocketmail.com

Thanks Jed! Here's what I have:

t1 SK30A-GR original
pin1: fluctuating voltages
pin2: fluctuating voltages
pin3: 14.97V

t2: 2N3906 new
*: left side after r76 14.98V
pin1: 2.665V
pin2: 2.115V
pin3: -4.99V

t3: 2SA798 original
pin1:4.99V
pin2:-13.19V
pin3: 5.54V
pin4: 4.99V
pin5: 4.90V

t4: 2N3906 new
pin1: -4.40V
pin2: -4.99V
pin3: -12.69V

t5: 2N3904 new
pin1: -4.99V
pin2: - 4.90V
pin3: - -14V draining to -13V and lower




Re: [PolySix] Re: Clone - MG always on by default

2014-10-16 by <backshall1@bellsouth.net>

Have you understood what Jed said about pins being different between the clone board and the original? The clone board is designed for 2N3819 in T1 position, not SK30A. The 2N transistor pins are Drain, Gate, Source, while the SK transistors are Source, Gate, Drain, so you have to bend the pins over to the correct hole if you are using the old original transistor.
 
Don Backshall.
 
Sent: Wednesday, October 15, 2014 5:29 PM
Subject: Re: [PolySix] Re: Clone - MG always on by default
 
 

Thanks Jed! Here's what I have:

t1 SK30A-GR original
pin1: fluctuating voltages
pin2: fluctuating voltages
pin3: 14.97V

t2: 2N3906 new
*: left side after r76 14.98V
pin1: 2.665V
pin2: 2.115V
pin3: -4.99V

t3: 2SA798 original
pin1:4.99V
pin2:-13.19V
pin3: 5.54V
pin4: 4.99V
pin5: 4.90V

t4: 2N3906 new
pin1: -4.40V
pin2: -4.99V
pin3: -12.69V

t5: 2N3904 new
pin1: -4.99V
pin2: - 4.90V
pin3: - -14V draining to -13V and lower



 

Re: [PolySix] Re: Clone - MG always on by default

2014-10-16 by Jed Jorgensen

Thanks, Don. That is it exactly. You have transistor leg in the wrong hole. Look up the data sheet for the 2N3819 vs the SK30A if you are not following what Don said.

On Thu, Oct 16, 2014 at 7:37 AM, backshall1@bellsouth.net [PolySix] <PolySix@yahoogroups.com> wrote:
 

Have you understood what Jed said about pins being different between the clone board and the original? The clone board is designed for 2N3819 in T1 position, not SK30A. The 2N transistor pins are Drain, Gate, Source, while the SK transistors are Source, Gate, Drain, so you have to bend the pins over to the correct hole if you are using the old original transistor.
 
Don Backshall.
 
Sent: Wednesday, October 15, 2014 5:29 PM
Subject: Re: [PolySix] Re: Clone - MG always on by default
 
 

Thanks Jed! Here's what I have:

t1 SK30A-GR original
pin1: fluctuating voltages
pin2: fluctuating voltages
pin3: 14.97V

t2: 2N3906 new
*: left side after r76 14.98V
pin1: 2.665V
pin2: 2.115V
pin3: -4.99V

t3: 2SA798 original
pin1:4.99V
pin2:-13.19V
pin3: 5.54V
pin4: 4.99V
pin5: 4.90V

t4: 2N3906 new
pin1: -4.40V
pin2: -4.99V
pin3: -12.69V

t5: 2N3904 new
pin1: -4.99V
pin2: - 4.90V
pin3: - -14V draining to -13V and lower



 


Re: [PolySix] Re: Clone - MG always on by default

2014-10-17 by f115@rocketmail.com

My apologies, guys. I completely misread the reply.

I switched the SK30A pins around. Still no change. I should mention that originally I had a 2N3819 installed but it didn't appear to make any difference for this issue. That's why I switched to an original and mistakenly installed it in reverse.

As a side issue, Cutoff doesn't work either but that's another matter.

Re: [PolySix] Re: Clone - MG always on by default

2014-10-17 by Jed Jorgensen

Hmm. Okay.

A couple questions:
1) How are your soldering skills? (Don't take this question personally, it's a big board and a lot of work.) On my own board a drop of solder bridged a connection underneath an IC and it took me ages to figure out what was going on. So...did you do a good job on the build? Any photos?

2) Have you checked the continuity between the connectors that lead to the front panel? I've seen acid damage the wires in the connectors (ugly and a pain to fix) so be sure that you have good continuity to your front panel.

j

On Fri, Oct 17, 2014 at 5:41 AM, f115@rocketmail.com [PolySix] <PolySix@yahoogroups.com> wrote:
 

My apologies, guys. I completely misread the reply.

I switched the SK30A pins around. Still no change. I should mention that originally I had a 2N3819 installed but it didn't appear to make any difference for this issue. That's why I switched to an original and mistakenly installed it in reverse.

As a side issue, Cutoff doesn't work either but that's another matter.


Re: [PolySix] Re: Clone - MG always on by default

2014-10-17 by f115@rocketmail.com

No offence taken, Jed!

Yeah I've been doing this for a little while. I haven't ever tackled a board like this but I have quite a few synth restorations and repairs under my belt. I have two other KLM's here to compare to. Both work fine in this test unit so I know that the connections are good.

These are kind of lousy photos but it may be a start. Flickr was having trouble uploading the whole pack of pictures I had so I have to it in batches.

Here's the album so far:

https://www.flickr.com/photos/metro_electro/sets/72157648405206117/

Thanks again!

Re: [PolySix] Re: Clone - MG always on by default

2014-10-17 by Jed Jorgensen

From what I can see it looks like a clean build. Are those old capacitors?

So from your previous emails my understanding is that the MG is always on and does not respond and the Cutoff does not work. Are there any other issues you have identified? And are there any parts that you reused that could be dodgy? 

This is going to quickly escape my trouble shooting skills but others on here will undoubtedly chime in.

On Fri, Oct 17, 2014 at 1:46 PM, f115@rocketmail.com [PolySix] <PolySix@yahoogroups.com> wrote:
 

No offence taken, Jed!

Yeah I've been doing this for a little while. I haven't ever tackled a board like this but I have quite a few synth restorations and repairs under my belt. I have two other KLM's here to compare to. Both work fine in this test unit so I know that the connections are good.

These are kind of lousy photos but it may be a start. Flickr was having trouble uploading the whole pack of pictures I had so I have to it in batches.

Here's the album so far:

https://www.flickr.com/photos/metro_electro/sets/72157648405206117/

Thanks again!


Re: [PolySix] Re: Clone - MG always on by default

2014-10-19 by f115@rocketmail.com

Hey Jed! I didn't want to leave this thread hanging. Family commitments. Yeah, the nearly all the parts are new. I reused the usual parts like the headers and CPU, then pulled the 798 13600s. Although not likely relevant here, I used a NOS 4560D for IC27 (instead of a Tl072). Memory was also NOS and sourced from our group here.

I'll have mot time with the board today and report back. The problem must be staring me in the face.

Re: [PolySix] Re: Clone - MG always on by default

2014-10-24 by f115@rocketmail.com

Well I'm afraid I haven't quite got the build right after all. I could really use the help.

- MG is on for sure
- Cutoff not working
- I can't write to patch either.  I tried saving patch A1 as a clean non modulated patch and it didn't pick it up.

I'm baffled. These seem to be somewhat unrelated! Cutoff certainly connects with the MG I/O on CN05 but then tape enable is on CN08.

Re: [PolySix] Re: Clone - MG always on by default

2014-10-24 by Bob Grieb

Does the op amp on the klm367 that buffers the cutoff voltage from the S&H change when you change the front panel control?

From: f115@rocketmail.com [PolySix] <PolySix@yahoogroups.com>;
To: <PolySix@yahoogroups.com>;
Subject: Re: [PolySix] Re: Clone - MG always on by default
Sent: Fri, Oct 24, 2014 4:17:12 PM

 

Well I'm afraid I haven't quite got the build right after all. I could really use the help.

- MG is on for sure
- Cutoff not working
- I can't write to patch either.  I tried saving patch A1 as a clean non modulated patch and it didn't pick it up.

I'm baffled. These seem to be somewhat unrelated! Cutoff certainly connects with the MG I/O on CN05 but then tape enable is on CN08.

Re: [PolySix] Re: Clone - MG always on by default

2014-10-24 by Bob Grieb

In manual mode you should be able to control the op amp buffer outputs by changing the front panel control. If that works, the the cpu is reading the cutoff pot correctly and selecting the right sample and hold channel to send out the voltage.

From: f115@rocketmail.com [PolySix] <PolySix@yahoogroups.com>;
To: <PolySix@yahoogroups.com>;
Subject: Re: [PolySix] Re: Clone - MG always on by default
Sent: Fri, Oct 24, 2014 4:17:12 PM

 

Well I'm afraid I haven't quite got the build right after all. I could really use the help.

- MG is on for sure
- Cutoff not working
- I can't write to patch either.  I tried saving patch A1 as a clean non modulated patch and it didn't pick it up.

I'm baffled. These seem to be somewhat unrelated! Cutoff certainly connects with the MG I/O on CN05 but then tape enable is on CN08.

Re: [PolySix] Re: Clone - MG always on by default

2014-11-01 by f115@rocketmail.com

Hi everyone -

Monumental update! It's all resolved.

I found and repaired the cutoff issue. It was simply trace damage in the PCB right at C26. I bridged it there and it worked. Bob, I tested it in manual mode as well and it check out. Incidentally I was able to calibrate the 367 all the way through each test procedure.

Most importantly the TC memory chip was faulty! That was the cause of the patch issues. I swapped it out with another one I had here and all was well.

I swear I thought I was going mad. I didn't think my build was that bad!

As always, thanks for all the help everyone. It's greatly appreciated. (And thanks for the repair offer Johannes! Another time!)

Have a great day!

Re: [PolySix] Re: Clone - MG always on by default

2014-11-01 by Jed Jorgensen

Great job!

On Nov 1, 2014 8:32 AM, "f115@rocketmail.com [PolySix]" <PolySix@yahoogroups.com> wrote:
 

Hi everyone -

Monumental update! It's all resolved.

I found and repaired the cutoff issue. It was simply trace damage in the PCB right at C26. I bridged it there and it worked. Bob, I tested it in manual mode as well and it check out. Incidentally I was able to calibrate the 367 all the way through each test procedure.

Most importantly the TC memory chip was faulty! That was the cause of the patch issues. I swapped it out with another one I had here and all was well.

I swear I thought I was going mad. I didn't think my build was that bad!

As always, thanks for all the help everyone. It's greatly appreciated. (And thanks for the repair offer Johannes! Another time!)

Have a great day!

Re: [PolySix] Re: Clone - MG always on by default

2014-11-03 by Dennis Matana

cool thnx for sharing the solution!

 
 
                           
On Saturday, November 1, 2014 5:23 PM, "Jed Jorgensen jed.jorgensen@gmail.com [PolySix]" <PolySix@yahoogroups.com> wrote:


 

Great job!

On Nov 1, 2014 8:32 AM, "f115@rocketmail.com [PolySix]" <PolySix@yahoogroups.com> wrote:
 

Hi everyone -

Monumental update! It's all resolved.

I found and repaired the cutoff issue. It was simply trace damage in the PCB right at C26. I bridged it there and it worked. Bob, I tested it in manual mode as well and it check out. Incidentally I was able to calibrate the 367 all the way through each test procedure.

Most importantly the TC memory chip was faulty! That was the cause of the patch issues. I swapped it out with another one I had here and all was well.

I swear I thought I was going mad. I didn't think my build was that bad!

As always, thanks for all the help everyone. It's greatly appreciated. (And thanks for the repair offer Johannes! Another time!)

Have a great day!