Vintage Synth Repair

I don't know if anyone can throw any suggestions on this one as VFD's are not exactly my area.

I have just got hold of an MKS70 but the display is almost impossible to read as all segments are lit with the ones that are supposed to be lit just a litle bit brighter (stick a red filter in front and you can make out some of it)

I have popped the display board out and had a look but apart from some residue of spider occupation which has now been cleaned off there is nothing visually amiss, my initial thoughts were that grid voltage is off for some reason but there is no indication of what it should be in the service notes, so on the basis that this display configuration seems to be used on a number of Roland synths, I thought it might be quicker to ask if anyone has encountered a similar problem in the past, I am just waiting for some replacement electrolytics (higher voltage than the ones I have in) for the inverter as a safe guard, but I am not fully inclined towards the caps as I would expect the display to dim if it were these.

So any suggestions greatly welcome.

Thanks

John

From: vintagesynthrepair@yahoogroups.com
[mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Adrian Corston
Sent: 28 February 2013 00:00
To: vintagesynthrepair@yahoogroups.com
Cc: johnhenryrose
Subject: Re: [vintagesynthrepair] Roland MKS70 Display problem

 

  

No complete answer for you, sorry, but here are some leads.  You are
certainly not alone.  Good luck!

http://www.facebook.com/pages/Noritake-VFD/208763672482987
http://www.gearslutz.com/board/electronic-music-instruments-electronic-music
-production/700306-screen-roland-mks70.html
http://www.youtube.com/watch?v=nHoD-DdgK9Y

Cheers,
A.


On 28/02/13 10:18 AM, johnhenryrose wrote:

  

I don't know if anyone can throw any suggestions on this one as VFD's are
not exactly my area.

I have just got hold of an MKS70 but the display is almost impossible to
read as all segments are lit with the ones that are supposed to be lit just
a litle bit brighter (stick a red filter in front and you can make out some
of it)

I have popped the display board out and had a look but apart from some
residue of spider occupation which has now been cleaned off there is nothing
visually amiss, my initial thoughts were that grid voltage is off for some
reason but there is no indication of what it should be in the service notes,
so on the basis that this display configuration seems to be used on a number
of Roland synths, I thought it might be quicker to ask if anyone has
encountered a similar problem in the past, I am just waiting for some
replacement electrolytics (higher voltage than the ones I have in) for the
inverter as a safe guard, but I am not fully inclined towards the caps as I
would expect the display to dim if it were these.

So any suggestions greatly welcome.

Thanks

John

----- Original Message -----

From: John Rose

To: vintagesynthrepair@yahoogroups.com

Sent: Thursday, February 28, 2013 12:12 AM

Subject: RE: [vintagesynthrepair] Roland MKS70 Display problem

Thanks Adrian,

I had seen some of that, but it all relates to the VFD becoming dim with age, the actual problem I have is the other way round, all the segments are on and quite bright making the display unreadable, a bit like if you have the contrast on an LCD cranked right up, this tends to suggest the VFD is probably OK but some bias voltage is causing all the segments to light up, I am convinced that it is probably a single voltage that is wrong that is causing the problem but it is just a case of finding the offender.

Many thanks

John Rose

(www.astrodevelopments.com)

From: vintagesynthrepair@yahoogroups.com [mailto:vintagesynthrepair@yahoogroups.com] On Behalf Of Adrian Corston
Sent: 28 February 2013 00:00
To: vintagesynthrepair@yahoogroups.com
Cc: johnhenryrose
Subject: Re: [vintagesynthrepair] Roland MKS70 Display problem

No complete answer for you, sorry, but here are some leads. You are certainly not alone. Good luck!

http://www.facebook.com/pages/Noritake-VFD/208763672482987
http://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/700306-screen-roland-mks70.html
http://www.youtube.com/watch?v=nHoD-DdgK9Y

Cheers,
A.


On 28/02/13 10:18 AM, johnhenryrose wrote:

I don't know if anyone can throw any suggestions on this one as VFD's are not exactly my area.

I have just got hold of an MKS70 but the display is almost impossible to read as all segments are lit with the ones that are supposed to be lit just a litle bit brighter (stick a red filter in front and you can make out some of it)

I have popped the display board out and had a look but apart from some residue of spider occupation which has now been cleaned off there is nothing visually amiss, my initial thoughts were that grid voltage is off for some reason but there is no indication of what it should be in the service notes, so on the basis that this display configuration seems to be used on a number of Roland synths, I thought it might be quicker to ask if anyone has encountered a similar problem in the past, I am just waiting for some replacement electrolytics (higher voltage than the ones I have in) for the inverter as a safe guard, but I am not fully inclined towards the caps as I would expect the display to dim if it were these.

So any suggestions greatly welcome.

Thanks

John

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