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Kronos 88 multiple keys above Middle C suddenly not working
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gilianamsterdam



Joined: 08 Jul 2017
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PostPosted: Sat Jul 08, 2017 9:27 pm    Post subject: Kronos 88 multiple keys above Middle C suddenly not working Reply with quote

Hi all,

I had a bizarre experience with my first generation Kronos 88 during a gig yesterday - in the middle of a performance all F keys above middle C stopped working. At first I was able to play around it Shocked but a song later all A's and C#'s above C4 ceased to work as well.

Does anyone know what the problem could be? I am located on the island of Ibiza in Spain and the closed service center is 600 kilometers away.

- I've tried opening up my Kronos and pushed some datacable connectors here and there to see if it was a loose cable connection but to no effect.

- I've tried running diagnostics mode and the Kronos passes all available tests.

- I've held the unit on its side (no easy feat with an 88 haha) as I read somewhere that that can work, but no.

- I've upgraded the firmware to latest version, 3.1.2.

It seems to me the problem has to be in the data connection located halfway on the RH3 keyboard (visible when removing the wooden underplate on the Kronos?

Any comments would be greatly appreciated, thanks!

Greetings from Ibiza,
Gil
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GregC
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PostPosted: Sun Jul 09, 2017 12:40 am    Post subject: Re: Kronos 88 multiple keys above Middle C suddenly not work Reply with quote

gilianamsterdam wrote:
Hi all,

I had a bizarre experience with my first generation Kronos 88 during a gig yesterday - in the middle of a performance all F keys above middle C stopped working. At first I was able to play around it Shocked but a song later all A's and C#'s above C4 ceased to work as well.


Gil


you don;t say what mode you are working in. That might be relevant
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AntonySharmman
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PostPosted: Sun Jul 09, 2017 12:55 am    Post subject: Re: Kronos 88 multiple keys above Middle C suddenly not work Reply with quote

gilianamsterdam wrote:
all F keys above middle C stopped working. At first I was able to play around it Shocked but a song later all A's and C#'s above C4 ceased to work as well.

This seems to be a hardware issue , symptoms of sequential muting of same notes usually shows either keybed board discontinued
connector cables nor key carbon switches that need maintenance !
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alland
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PostPosted: Sun Jul 09, 2017 8:15 am    Post subject: Reply with quote

Most probably connector between keyboard lower (CN9) and upper (CN7) PCB and particularly pins 1 and 2 that carry scan codes for keys you mention.
Keyboard lower PCB (keys A0-E4) is connected to scan controller board and needed scan lines are extended from lower keyboard PCB to upper PCB (keys F4-CCool.
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gilianamsterdam



Joined: 08 Jul 2017
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PostPosted: Sun Jul 09, 2017 5:32 pm    Post subject: Reply with quote

alland wrote:
Most probably connector between keyboard lower (CN9) and upper (CN7) PCB and particularly pins 1 and 2 that carry scan codes for keys you mention.
Keyboard lower PCB (keys A0-E4) is connected to scan controller board and needed scan lines are extended from lower keyboard PCB to upper PCB (keys F4-CCool.


Thanks for the quick response guys

@alland I will first try to confirm that that specific connector is well connected. Just to be sure, do you mean the one in the picture attached? There is one datacable style connector that can be disconnected, and one white structure underneath that seems to be permanent. Did you mean pin 1 and 2 in the datacable?

[img]http://imgur.com/a/F7Epo[/img]
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Derek Cook
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PostPosted: Sun Jul 09, 2017 6:05 pm    Post subject: Reply with quote

Hi.

The first thing I would do in this instance is open the Kronos up and check all of the connectors between the keyboard and the circuit boards. In fact check all connectors and (might not be relevant for the Kronos) any chips that are socketed, I would give them a firm push as well.

I would actually pull connectors out and reconnect them, as connectors can tarnish and oxidise as well as slowly "creep" due to heating and cooling, which can all lead to marginal connections.

The fact that all Fs stopped working first implies a bad connection or fault somewhere in the key scanning path.
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gilianamsterdam



Joined: 08 Jul 2017
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PostPosted: Sun Jul 09, 2017 6:15 pm    Post subject: Reply with quote

Derek Cook wrote:
Hi.

The first thing I would do in this instance is open the Kronos up and check all of the connectors between the keyboard and the circuit boards. In fact check all connectors and (might not be relevant for the Kronos) any chips that are socketed, I would give them a firm push as well.

I would actually pull connectors out and reconnect them, as connectors can tarnish and oxidise as well as slowly "creep" due to heating and cooling, which can all lead to marginal connections.

The fact that all Fs stopped working first implies a bad connection or fault somewhere in the key scanning path.


Thanks Derek I will do this!
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alland
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PostPosted: Sun Jul 09, 2017 6:30 pm    Post subject: Reply with quote

gilianamsterdam wrote:
@alland I will first try to confirm that that specific connector is well connected. Just to be sure, do you mean the one in the picture attached? There is one datacable style connector that can be disconnected, and one white structure underneath that seems to be permanent. Did you mean pin 1 and 2 in the datacable?
[img]http://imgur.com/a/F7Epo[/img]


Yes, connections on picture are under suspicion Smile . I cannot see any markings on image (too low resolution), but schematics says, that there are two connections between keyboard PCBs - CN7<->CN9 where most probably is fault (pin1-2) and CN4<->CN8 (that should be OK). Permanent (soldered) connections are most probably OK, but who knows.
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gilianamsterdam



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PostPosted: Thu Aug 03, 2017 3:33 pm    Post subject: Reply with quote

alland wrote:


Yes, connections on picture are under suspicion Smile . I cannot see any markings on image (too low resolution), but schematics says, that there are two connections between keyboard PCBs - CN7<->CN9 where most probably is fault (pin1-2) and CN4<->CN8 (that should be OK). Permanent (soldered) connections are most probably OK, but who knows.


Hi it took me a while due to busy summer schedule but I've finally gotten down with the Kronos and unfortunately have to report I couldn't fix it.

Of the two connections between keyboard PCBs indeed only one can be disconnected, which I did numerous times. I don't know exactly which one is CN7<->CN9 and which one is CN4<->CN8. All the connectors look fine and not oxidated.

Alland would you (or anyone else with Kronos skills) be up for assisting me with fixing this? Perhaps over Skype? I am located on Ibiza and traveling to a repair center would be quite expensive. I would be willing to pay you. I would love to play my Kronos again ;(

Many thanks for your help so far, take care, Gil
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KK
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PostPosted: Thu Aug 03, 2017 9:10 pm    Post subject: Reply with quote

Hi there,

To be able to fix this yourself, you need to have some basic experience with soldering tiny connections on PCBs, and also you need decent tools (iron with tiny tip, soldering with resin center, ohmmeter/multimeter, etc.). You also need to know about basic precautions like how to avoid any ESD, otherwise there's a risk to damage your Kronos way beyond this problem.

If you are OK with that, then next step would be to take a close and in focus pic of the two connectors. Your problem is likely in the wire group which has 8 conductors, not the one which has 12.

From there, it is likely to be what alland mentioned. It also is logical, since the broken connection(s) (T00 and/or T01) is/are on one side of a connector, which means something gave up after being under stress. Solution will simply be to resolder the thing correctly or create new jumper(s) if the part is unavailable or PCB trace which accommodates the connector is broken, etc. It all depends what you can see and/or measure with meter, etc.
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gilianamsterdam



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PostPosted: Mon Aug 07, 2017 9:13 am    Post subject: Reply with quote

KK wrote:
Hi there,

To be able to fix this yourself, you need to have some basic experience with soldering tiny connections on PCBs, and also you need decent tools (iron with tiny tip, soldering with resin center, ohmmeter/multimeter, etc.). You also need to know about basic precautions like how to avoid any ESD, otherwise there's a risk to damage your Kronos way beyond this problem.

If you are OK with that, then next step would be to take a close and in focus pic of the two connectors. Your problem is likely in the wire group which has 8 conductors, not the one which has 12.

From there, it is likely to be what alland mentioned. It also is logical, since the broken connection(s) (T00 and/or T01) is/are on one side of a connector, which means something gave up after being under stress. Solution will simply be to resolder the thing correctly or create new jumper(s) if the part is unavailable or PCB trace which accommodates the connector is broken, etc. It all depends what you can see and/or measure with meter, etc.


Hi KK, thanks for your quick reply!

I am willing to do the soldering myself and have a multimeter at hand.

The strange thing is, from what I can tell both connectors seem spotless. There is no corrosion or oxidation visible. I have uploaded some pictures to imgur to illustrate: http://imgur.com/a/RmpGm
What do you think would need soldering here?

Could it be that the damage is on the other side of the PCBs? I suppose I would need to remove the RH3 keyboard to inspect that part. What is the procedure for doing this?

Many thanks for your help,

Kind regards,

Gilian
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AntonySharmman
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PostPosted: Mon Aug 07, 2017 9:50 am    Post subject: Reply with quote

According to pictures , you're searching the wrong PCB connectors , inspection should be at the global one
that leads to controller board !
It might not be the PCB connectors , if not violently tighten at chassis and not oxidized , soldering is a very
rare solution there that might make things worst !
Disassemble relative keybed board , clean (even replace) all carbon contack key switches and try again !
I've already written that in my initial post and it's the fundamental maintenance for an old keybed !
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gilianamsterdam



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PostPosted: Mon Aug 07, 2017 10:09 am    Post subject: Reply with quote

AntonySharmman wrote:
According to pictures , you're searching the wrong PCB connectors , inspection should be at the global one
that leads to controller board !
It might not be the PCB connectors , if not violently tighten at chassis and not oxidized , soldering is a very
rare solution there that might make things worst !
Disassemble relative keybed board , clean (even replace) all carbon contack key switches and try again !
I've already written that in my initial post and it's the fundamental maintenance for an old keybed !


Hi Antony, thanks for your reply. The pictures are of the connector between keyboard lower (CN9) and upper (CN7) PCB based on KK and alland's instructions. Thanks, I will check the global one again as well.

What do you mean exactly by violently tighten at chassis?

What is the procedure for disassembling the keybed board? I am in possession of a few pages of the service manual but not those explaining keyboard removal.

Thanks for your help,
Gilian
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AntonySharmman
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PostPosted: Mon Aug 07, 2017 10:18 am    Post subject: Reply with quote

- I've noticed in some Kronos (in my lab) that global connector was tightly fastened in chassis borders with straps
and sometimes traveling vibrations could violate it or just slightly be removed from socket !
- You do not disassemble the whole keybed ... You just remove carefully PCB screws and every keybed board is
easily released for maintance !
Note that you must never tightly fasten these screws while assembling !!!
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KK
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PostPosted: Mon Aug 07, 2017 9:10 pm    Post subject: Reply with quote

gilianamsterdam wrote:
Hi KK, thanks for your quick reply!

I am willing to do the soldering myself and have a multimeter at hand.

The strange thing is, from what I can tell both connectors seem spotless. There is no corrosion or oxidation visible. I have uploaded some pictures to imgur to illustrate: http://imgur.com/a/RmpGm
What do you think would need soldering here?

Could it be that the damage is on the other side of the PCBs? I suppose I would need to remove the RH3 keyboard to inspect that part. What is the procedure for doing this?

Many thanks for your help,

Kind regards,

Gilian

Hi there,

The connectors seem indeed just fine on the pics, even though it doesn't prove they are. Of course, the problem could be elsewhere, but from the info you mentioned, it looks like this bridge could be the cause. I could help you by opening my Kronos, but it's still under warranty until November. But by then I plan to open it to do a few simple mods. Wink

If it would be my problem, I would now check the continuity (ohmmeter) between the 8-pin female connector first and second pins (which correspond to T00 and T01 - which are on one of the sides) up to the PCB trace that goes to the next point where you can place a probe. Same on the other PCB which makes the bridge, I would check the continuity between the male "wire" connector's T00 and T01 pins on the other PCB up to the individual next trace points where they go so you can place your probe. Of course for this you will have to unscrew the PCB to go under them. A lack of continuity would confirm where is the problem. There could also be something somewhere around there causing a short on one of those pins, causing the malfunction.

Again, this from the info supplied. I can only offer limited help, but that is what I would check next.
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