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Korg SV1 malfunction: freezes while playing! need help, pls

 
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gosus



Joined: 05 Nov 2017
Posts: 12

PostPosted: Mon Nov 27, 2017 10:49 am    Post subject: Korg SV1 malfunction: freezes while playing! need help, pls Reply with quote

hi everyone!
my Korg SV1 freezes while i playing on it (with notes sounding enlessly, and no button responding). more notes played simultaneously - more chances it will freeze. more complicated the synthesis of a voice chosen - more chances for failure. After power off and on in works ok again, and then again gets stuck.
Here is the video: https://youtu.be/gKyeByDYdDc
it is running under OS v1.3 now (i have upgraded from v1.2, but the problem remains the same). I've opened it's case and checked all boards connections and wires - found nothing suspicious.
what else can i do to fix it?
many thanks
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voip
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Joined: 27 Nov 2014
Posts: 3758

PostPosted: Mon Nov 27, 2017 9:23 pm    Post subject: Reply with quote

Difficult to be sure of exactly where the problem lies but, since it seems to be polyphony-related, and the more complex the sound the sooner the problem arises, a possible cuplrit might be be the memory; either a fault in the memory itself, or in the memory address or data lines. As such, it will probably require the main board to be replaced, which is unfortunately not cheap; $880.50 from:

https://www.guitar-parts.com/catalog/korg-sv173-sv188-main-board-gra0002143

Replacing the memory devices is an option, but there's no guarantee of success, so a bit of a gamble, but certainly a lot cheaper than a new main board.

The chips are: K4S641632K-UC75 for the effects SDRAM and V54C3256164VDI7PC for the main processor SDRAM.
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gosus



Joined: 05 Nov 2017
Posts: 12

PostPosted: Tue Nov 28, 2017 9:55 am    Post subject: Reply with quote

Thank you for information!
Of course, i'll try to replace memory.
How many chips do i need?
Where can i buy them?
thank you so much!
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voip
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Joined: 27 Nov 2014
Posts: 3758

PostPosted: Tue Nov 28, 2017 7:25 pm    Post subject: Reply with quote

One of each memory device type is fitted to the SV-1 main board.

As for sourcing the parts, use a search engine, and/or go to sites like Mouser, or Digikey, or Farnell, or the bay of thieves. The decision on where to buy from may be influenced by your location.

.
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gosus



Joined: 05 Nov 2017
Posts: 12

PostPosted: Thu Nov 30, 2017 5:08 pm    Post subject: Reply with quote

voip wrote:

The chips are: K4S641632K-UC75 for the effects SDRAM and V54C3256164VDI7PC for the main processor SDRAM.


i am very sorry, but where did you find V54C3256164VDI7PC?

i am reading the service manual right now and see
"SDRAM 64MB 16B K4S641632K-UC75
SDRAM256Mb MT48LC16M16A2P-75:D"
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voip
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Joined: 27 Nov 2014
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PostPosted: Thu Nov 30, 2017 10:12 pm    Post subject: Reply with quote

Hmm, yes, it seems the schematic gives V54C3256164VDI7PC for the 256MB SDRAM and the parts list shows the SDRAM part as: MT48LC16M16A2P-75:D.

May I suggest looking at the part actually fitted to the mainboard to get the definitive answer.
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gosus



Joined: 05 Nov 2017
Posts: 12

PostPosted: Sat Dec 02, 2017 9:34 am    Post subject: Reply with quote

voip wrote:
May I suggest looking at the part actually fitted to the mainboard to get the definitive answer.


thanks, will go this way.
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gosus



Joined: 05 Nov 2017
Posts: 12

PostPosted: Thu Apr 05, 2018 3:52 am    Post subject: Reply with quote

voip wrote:
Hmm, yes, it seems the schematic gives V54C3256164VDI7PC for the 256MB SDRAM and the parts list shows the SDRAM part as: MT48LC16M16A2P-75:D.

May I suggest looking at the part actually fitted to the mainboard to get the definitive answer.


Both memory modules replacement made a fix!
my SV1 works perfectly!
thanks a lot!
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gosus



Joined: 05 Nov 2017
Posts: 12

PostPosted: Mon Sep 10, 2018 9:27 pm    Post subject: Reply with quote

hi!
will sell motherboard for $400
onanko@mail.ru
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