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PA600 MotherBoard Reference Number(s)

 
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sridharar
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Joined: 29 Apr 2013
Posts: 130
Location: Nashua, NH

PostPosted: Fri Apr 27, 2018 5:36 pm    Post subject: PA600 MotherBoard Reference Number(s) Reply with quote

I am wondering if anyone has the PA600 service manual or even without it can provide the reference number for its Mother Boards for ordering.

I am considering replacing the board where the harness from the Joystick plugs in and manages Pitch bend and Modulation.

A service technician replaced one of the inductors (R19) that is on the Pitch Bend path, with some approximate component, and now the Pitch takes a long time to get back to neutral -- though the physical joystick returns fast. For some reason, the service technician does not respond to my mails(s).

If some one has a the part number for that inductor it would be great help as well, so I do not have to change the board but just that inductor.

Thanks in advance Sri.
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musiccankill
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Location: Greece

PostPosted: Tue May 01, 2018 4:25 pm    Post subject: Reply with quote

Hello.
Here is the diagram of this specific area..
As you can see there is no written value to it..Check for continuity and resistance (it should be the same as the other 2 inductors)..
https://imgur.com/a/NqbOuca
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sridharar
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Joined: 29 Apr 2013
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Location: Nashua, NH

PostPosted: Wed May 02, 2018 9:41 pm    Post subject: Reply with quote

Thanks very much for the Schematic MuisicCanKill.

Wonder whether you have the picture of the actual Motherboard that maps to this schematic. (Would save me from dismantling the keyboard to see that board - and I vividly which was changed with an approximate component). I might have taken some pictures on my iPad while at the Service shop and will also check.

br Sri.
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sridharar
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Joined: 29 Apr 2013
Posts: 130
Location: Nashua, NH

PostPosted: Wed May 02, 2018 10:25 pm    Post subject: Reply with quote

MusicCanKill

I had taken one picture and found it. Here is a link to it.

https://drive.google.com/file/d/1Nd9KMgxgfsafJUw-ErcEXsaqCreChjHy/view?usp=sharing

L19 is the one, in the picture, that was changed with an approximate one, causing the pitch lag problem now.

My recall is, service technician saying, that it was on the Pitch Bend (i.e X axis of Joystick) pathway. May be was wrong on that -- though that component was the one which was charred and shot.

But your schematic shows that pitch bend inductor as L17 which is much more to the left in my picture above. That was not changed.

But your schematic does have L17, L18, L19.

Unfortunately there are no values indicated for them for me to get from an Electronic Store.

Debating whether to replace the whole board or just the L17, 18, 19 elements. (latter would be ideal if I can manage it).

br Sri.
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musiccankill
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PostPosted: Wed May 02, 2018 10:57 pm    Post subject: Reply with quote

If you have some basic soldering skills i would say that you should try to measure the Ohms across the 3 inductors...It should be something really close to 0 Ohms for the 3 of them (which means they are there for filtering noise from power supply and may not even be necessary).In that case remove the changed component and short circuit it to test ..
I doubt this is the source of your problem though as it seems to affect both X and Y axis so both should have latency...
I d say check the rest of the components for correct values..
If these don't solve your issue upload a sound sample or better a video of the latency problem if you wish cause it may not be related to this area at all...
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sridharar
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Location: Nashua, NH

PostPosted: Thu May 03, 2018 2:14 am    Post subject: Reply with quote

Musiccankill

Thanks for the follow-on.

Service Technician did measure the component after it was taken off - and it was open. Similar ones on the board measures almost zero - ignoring that there may be other paths - that was expected.

As an inductor, I would think it was trying to keep out high frequencies - and not the lows. I sort of opined with him that it was cutting off high frequency pulses coming off the Joystick movements.

In terms of what is happening:

a) Y axis which is set for modulation works fine
b) X axis: (with Pitch bend range to set to 1)

right side (increasing the pitch) movements are working fine, I cannot observe any difference

left side (decreasing pitch bend) it bends down fine. But returning back to original pitch has an unacceptable lag -- destroys the music


(so my guess is that the inductor value is probably much higher preventing fast ramp of the pitch).

c) So essentially I set Pitch Bend range to zero, nowadays, when I play.

Back..

To your comment, Yes I can try shorting that inductor and check what happens. I would assume designers would have had some very valid reason for the inline inductor.

I will try to do this over the weekend.. as dismantling and assembling back takes a few hours.

Incidentally...

I do not face Pitch bend problems when I am using Midi for input and my iPad(Geoshred) as the midi controller. I set the PB range to the max i.e 12 and iPad app is also set to the same. All my expressions on the multi touch surface play fine. Geoshred uses only Pitch Bend for all shakes, glides etc.
So I am thinking that rest of the board is working fine.

Appreciate your taking the time for these exchanges.

If I can figure out the spec for L17-L19 it would be perfect. Unlike resistors, I do not know a way to measure inductance (certainly not with my multimeter).

br Sri.
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sridharar
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Location: Nashua, NH

PostPosted: Thu May 03, 2018 1:32 pm    Post subject: Reply with quote

Musiccankill

Any chance you have the reference number of the part number for the board on which this circuitry resides. If I had already asked appreciate your indulgence.

To your other suggestion, I will try to create a video to share the issue.

br sri.
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musiccankill
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PostPosted: Sun May 06, 2018 10:22 am    Post subject: Reply with quote

GRA0002179 PA600 PANEL BOARD
The readings of the pitch bend /modulation are happening on this board i m sure you don't need to change it.It can be fixed...
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sridharar
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Joined: 29 Apr 2013
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Location: Nashua, NH

PostPosted: Mon May 07, 2018 7:26 pm    Post subject: Reply with quote

Musiccankill

Thanks so much for the reference details.
I truly appreciate your strong direction that the existing board can be repaired and need not be replaced. I am going to give it my best try.
Will have to find out the specs for those three inductors.
(I am quite comfortable playing with electronic things, my first degree is in Electrical Engineering).

regards Sri.
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musiccankill
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PostPosted: Wed May 09, 2018 7:47 am    Post subject: Reply with quote

You can get an LCR meter and put one in to see its value but i recommend to first measure across one with an ohm meter.. if it appears like a short circuit i would short the pads that the one the repair guy had changed and most probably it would fix it...
Are you sure no other components have been changed?
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sridharar
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Joined: 29 Apr 2013
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Location: Nashua, NH

PostPosted: Thu May 10, 2018 2:04 pm    Post subject: Reply with quote

Thanks for the tip Musiccankill.
I will probably get an LCR meter which I do not have.
But I can certainly do a temporary jumper to check how it behaves - and if it works, I think it should - as the service technician also suggested that and I was afraid of reducing that inductor value to zero. I wish he had tried this while the keyboard was open, and also before putting another approximate component.

I will give this a go this weekend.

br Sri.
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musiccankill
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PostPosted: Thu May 10, 2018 5:38 pm    Post subject: Reply with quote

The inductor there is just a filter (to filter out high frequency noise that may be present for no specific reason) so there is no problem removing it other than it may behave a bit strange some times if the high frequency signals nearby are too high...
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