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Sound path
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mkeschinger



Joined: 07 Oct 2021
Posts: 21

PostPosted: Tue Oct 19, 2021 6:04 am    Post subject: Sound path Reply with quote

Hey guys, time to get technical and geeky.
My kronos 2 88 was hit by lightning while playing. Now in order to hear it, I need to have the volume max and the PA max. So, it's getting signal, but not volume.
Turns on fine and all functions seem to work EXCEPT the sound... Does the audio jack board control that or is that all done on the main board? OR am I missing a board to look at?
I appreciate the help!

M K
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voip
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PostPosted: Tue Oct 19, 2021 9:12 am    Post subject: Reply with quote

Did the lightning bolt actually strike the keyboard itself?? In which case you're lucky to be alive!!

In common with just about all audio and consumer gear, the Kronos is not "hardened" against such events. What else was connected to the Kronos when the lightning strike occurred?

One thing worth trying is to route the audio to the other outputs, 1 to 4, and see what happens.

.
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mkeschinger



Joined: 07 Oct 2021
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PostPosted: Wed Oct 20, 2021 10:28 pm    Post subject: Reply with quote

voip wrote:
Did the lightning bolt actually strike the keyboard itself?? In which case you're lucky to be alive!!

In common with just about all audio and consumer gear, the Kronos is not "hardened" against such events. What else was connected to the Kronos when the lightning strike occurred?

One thing worth trying is to route the audio to the other outputs, 1 to 4, and see what happens.

.

Hit the house while it was on and I was playing it. Fried something in it.
Tried all outputs. Nothing more than minimal sound.
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alland
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PostPosted: Thu Oct 21, 2021 4:40 am    Post subject: Reply with quote

If ALL outputs behave similarly (including headphones, L/R, Individual 1-4) then issue is probably on Jack board (KLM 3005).
This can be related to "Mute All" functionality that mutes (kind a shorts) all outputs until Power is Good when turning Kronos on - to avoid pops and noise.
Mute All functionality depends directly on two signals from Power Unit - that could be also easily checked - "Standby +5" and "Power Good" - standard ATX power unit signals.
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mkeschinger



Joined: 07 Oct 2021
Posts: 21

PostPosted: Thu Oct 21, 2021 4:52 am    Post subject: Reply with quote

alland wrote:
If ALL outputs behave similarly (including headphones, L/R, Individual 1-4) then issue is probably on Jack board (KLM 3005).
This can be related to "Mute All" functionality that mutes (kind a shorts) all outputs until Power is Good when turning Kronos on - to avoid pops and noise.
Mute All functionality depends directly on two signals from Power Unit - that could be also easily checked - "Standby +5" and "Power Good" - standard ATX power unit signals.


How do I check that?
Is it possible that the power unit inside the board is just not putting out enough juice?
Sorry, still learning. Smile

M
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alland
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PostPosted: Thu Oct 21, 2021 6:36 am    Post subject: Reply with quote

1) You cannot check that without opening keyboard. If you have valid warranty and reasonable ways to get your board repaired under warranty, go there.
2) If you want do it yourself and on your own responsibility then
a) Download Korg Kronos Service manual, easily found with Google
b) Open your Kronos, study Kronos schematic and determine where to measure voltages - there are two versions on Audio Jack boards, one of them having additronal "Mute buffer" unit. Audio Jack module to study is KLM-3005. There should be special two wire bundle coming from Power unit (PSU) with +5VSTB and PowerGood signals.
c) Have voltmeter with you and check, if signals from PSU are correct (Rewer generic ATX power supply reference for correct values but +5Vstb shluld be +5V all times when Power unit plugged in, Power Good must go from 0 to +5 when Power Supply swiched on and all output voltages are at their respective levels.
d) If PSU is not giving correct signals, repair/order new
e) If PSU gives correct signals then investigate Mute All chain on KLM-3005. If it has special Mute Buffer (KLM 3167) check its functioning (purpose is just to repeat and amplify Power OK signal)
f) Check Mute All switching transistor (Q606). In standby (Kronos not switched on) its collector (also called signal "Mute_A") must have positive voltage (that opens all muting trasistors that will short all audio signal output paths). Iw Power OK signal comes to +5 after switching Kronos on, the mute switch transistor Q606 closes, its collector (and Mute_A signal) comes to zero and even negative that closes all shorting mute transistors. Possible reason with your problem is that Mute_A is not getting zero/negative enough causing "partial muting" of your sound in all channels.
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geoelectro
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PostPosted: Thu Oct 21, 2021 12:47 pm    Post subject: Reply with quote

alland wrote:
1) You cannot check that without opening keyboard. If you have valid warranty and reasonable ways to get your board repaired under warranty, go there.

Warranty does not cover damage caused externally. Lightning, floods, dropped etc. would not be covered by a warranty. Insurance may cover it if you have a policy in place.

Geo
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mkeschinger



Joined: 07 Oct 2021
Posts: 21

PostPosted: Thu Oct 21, 2021 3:40 pm    Post subject: Reply with quote

alland wrote:
1) You cannot check that without opening keyboard. If you have valid warranty and reasonable ways to get your board repaired under warranty, go there.
2) If you want do it yourself and on your own responsibility then
a) Download Korg Kronos Service manual, easily found with Google
b) Open your Kronos, study Kronos schematic and determine where to measure voltages - there are two versions on Audio Jack boards, one of them having additronal "Mute buffer" unit. Audio Jack module to study is KLM-3005. There should be special two wire bundle coming from Power unit (PSU) with +5VSTB and PowerGood signals.
c) Have voltmeter with you and check, if signals from PSU are correct (Rewer generic ATX power supply reference for correct values but +5Vstb shluld be +5V all times when Power unit plugged in, Power Good must go from 0 to +5 when Power Supply swiched on and all output voltages are at their respective levels.
d) If PSU is not giving correct signals, repair/order new
e) If PSU gives correct signals then investigate Mute All chain on KLM-3005. If it has special Mute Buffer (KLM 3167) check its functioning (purpose is just to repeat and amplify Power OK signal)
f) Check Mute All switching transistor (Q606). In standby (Kronos not switched on) its collector (also called signal "Mute_A") must have positive voltage (that opens all muting trasistors that will short all audio signal output paths). Iw Power OK signal comes to +5 after switching Kronos on, the mute switch transistor Q606 closes, its collector (and Mute_A signal) comes to zero and even negative that closes all shorting mute transistors. Possible reason with your problem is that Mute_A is not getting zero/negative enough causing "partial muting" of your sound in all channels.




You mentioned the 3005. That is the digital out board. The audio jack is 3006. Is that a typo or does the digital out transmit to the audio out? Which I suppose would make sense.. Just want to clarify. There is no warranty left on the keyboard and the insurance is covering a new one. BUT I don't mind the idea of fixing this one on my own. The repair place couldn't do it, because they need to use new parts and there aren't any. But I can use used parts or replace transistors, if they are available. Wink
Thanks you!
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alland
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PostPosted: Thu Oct 21, 2021 6:16 pm    Post subject: Reply with quote

mkeschinger wrote:
You mentioned the 3005. That is the digital out board. The audio jack is 3006. Is that a typo or does the digital out transmit to the audio out? Which I suppose would make sense.. Just want to clarify. There is no warranty left on the keyboard and the insurance is covering a new one. BUT I don't mind the idea of fixing this one on my own. The repair place couldn't do it, because they need to use new parts and there aren't any. But I can use used parts or replace transistors, if they are available. Wink
Thanks you!


My Kronos and Kronos Service manual v2.0 (can be downloaded from https://www.synthxl.com/korg-kronos/) says:
1) KLM-3005 is analog output (pages 20/21) that has Mute_All circuitry.
2) KLM-3006 is digital output and is not relevant in this topic (controls MIDI, SP/DIF, keybed and other I/O)
3) Both KLM-3005 and KLM-3006 gets their data from KLM-3002 (refer to block diagram on page Cool
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mkeschinger



Joined: 07 Oct 2021
Posts: 21

PostPosted: Sun Oct 24, 2021 4:24 pm    Post subject: Reply with quote

alland wrote:
mkeschinger wrote:
You mentioned the 3005. That is the digital out board. The audio jack is 3006. Is that a typo or does the digital out transmit to the audio out? Which I suppose would make sense.. Just want to clarify. There is no warranty left on the keyboard and the insurance is covering a new one. BUT I don't mind the idea of fixing this one on my own. The repair place couldn't do it, because they need to use new parts and there aren't any. But I can use used parts or replace transistors, if they are available. Wink
Thanks you!


My Kronos and Kronos Service manual v2.0 (can be downloaded from https://www.synthxl.com/korg-kronos/) says:
1) KLM-3005 is analog output (pages 20/21) that has Mute_All circuitry.
2) KLM-3006 is digital output and is not relevant in this topic (controls MIDI, SP/DIF, keybed and other I/O)
3) Both KLM-3005 and KLM-3006 gets their data from KLM-3002 (refer to block diagram on page Cool


Weird. ok. The manual I was looking at had 3005 (d-Jack) on page 7- the parts list page. SOrry about that. I will check out page 8 right now! Smile Thanks again!
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mkeschinger



Joined: 07 Oct 2021
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PostPosted: Sun Oct 24, 2021 5:12 pm    Post subject: Reply with quote

mkeschinger wrote:
alland wrote:
mkeschinger wrote:
You mentioned the 3005. That is the digital out board. The audio jack is 3006. Is that a typo or does the digital out transmit to the audio out? Which I suppose would make sense.. Just want to clarify. There is no warranty left on the keyboard and the insurance is covering a new one. BUT I don't mind the idea of fixing this one on my own. The repair place couldn't do it, because they need to use new parts and there aren't any. But I can use used parts or replace transistors, if they are available. Wink
Thanks you!


My Kronos and Kronos Service manual v2.0 (can be downloaded from https://www.synthxl.com/korg-kronos/) says:
1) KLM-3005 is analog output (pages 20/21) that has Mute_All circuitry.
2) KLM-3006 is digital output and is not relevant in this topic (controls MIDI, SP/DIF, keybed and other I/O)
3) Both KLM-3005 and KLM-3006 gets their data from KLM-3002 (refer to block diagram on page Cool


Weird. ok. The manual I was looking at had 3005 (d-Jack) on page 7- the parts list page. SOrry about that. I will check out page 8 right now! Smile Thanks again!

ok
Looks like we have 0 when plugged in but not turned on and then +5.03 like we should and it goes to 11.99 for the 12v at the 12v connection on 3005. Is there enough of a tolerance for that? I will check out the mute chain next. At least the haystack is getting smaller right? Wink Thanks!
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KK
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PostPosted: Mon Oct 25, 2021 12:30 am    Post subject: Reply with quote

Another important thing to consider is that the PCB part numbers in a K2 are NOT the same as the ones listed in the service manual (which were for earlier Kronos models). So you won't find a KLM-3305 in a K2. Instead the K2 PCMs are numbered like KLM-3360, KLM-3361, etc. This so that you don't order or buy a PCB that might not work in your unit.
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mkeschinger



Joined: 07 Oct 2021
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PostPosted: Mon Oct 25, 2021 3:31 am    Post subject: Reply with quote

KK wrote:
Another important thing to consider is that the PCB part numbers in a K2 are NOT the same as the ones listed in the service manual (which were for earlier Kronos models). So you won't find a KLM-3305 in a K2. Instead the K2 PCMs are numbered like KLM-3360, KLM-3361, etc. This so that you don't order or buy a PCB that might not work in your unit.

Yeah, saw that right away. Same with the circuit boards. Quick question on that though, will the older boards work in a k2? For example 3005 in a K2?
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KK
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PostPosted: Mon Oct 25, 2021 5:46 am    Post subject: Reply with quote

IMHO I think it would be asking for more problems. Wink
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alland
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PostPosted: Mon Oct 25, 2021 6:54 am    Post subject: Reply with quote

mkeschinger wrote:
Looks like we have 0 when plugged in but not turned on and then +5.03 like we should and it goes to 11.99 for the 12v at the 12v connection on 3005. Is there enough of a tolerance for that? I will check out the mute chain next. At least the haystack is getting smaller right? Wink Thanks!


I do not understand, what signals you are describing - just +5 and +12? If so, then those voltages seem to be good.
Rather interesting would be what does MUTE_A (on board KLM-3005, see page 20/21 on Korg maintenance manual)?
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