KR-4500 Schematics

Everything else from Roland that doesn't fit elsewhere
phil__
Posts: 2
Joined: 13:29, 21 January 2010
Location: Nice, France

Re: KR-4500 Schematics

Post by phil__ »

Hi Sharon and Anton, I am new on this forum and have the same problem with my KR 4500.
Could you forward me the diagram, I will try to change the capacitors with the help of a friend who know how to do it?

Thanks in advance,

Phil

(there was a mistake in my email, I corrected that)
gcrocker
Posts: 3
Joined: 22:48, 4 May 2010

Re: KR-4500 Schematics

Post by gcrocker »

Anton,

Very cool that you got your KR working again! Did you replace the regular capacitors or the surface mount ones? I notice on my main board that the surface mount caps have holes nearby for standard replacements.

Seems like a heat gun is the easiest way to remove the old surface mount ones. Is that what you did?

Thanks!

-glenn
Uncle_Victor
Posts: 2
Joined: 15:57, 5 July 2010

Re: KR-4500 Schematics

Post by Uncle_Victor »

Be very very carefull with that heatgun...
I really suggest you find someone with the knowledge of pcb repair and who has the proper equipment.
It 's not difficult to damage a pcb in such a way that it is unrepairable.

If you wish I'll keep you informed on how to do it; my son just reported that his KR4500 has the same problem, so I will replace the leaky capacitors when it arrives in the lab.
virnan
Posts: 1
Joined: 22:28, 21 July 2010

Re: KR-4500 Schematics

Post by virnan »

Hi Anton,
My KR 4500 has started to snap and crackle along with outgassing an amine odor. I would be very pleased if you could send me the schematics.
Thanks, Virgil
virnan@charter.net
Beaver
Posts: 2
Joined: 15:24, 27 August 2010

Re: KR-4500 Schematics

Post by Beaver »

Hello Anton
I too have a problem with a KR 4500 main board. Crackling , bad small. I have found smoke from C48.
I have where I cab buy smd electrolytic caps but none of the ones available are marked like the ones on the board.
20 are marked 26 10 16V
6 are marked 26 3.3 50V
4 are marked 23 10 25
and 1 is marked 24 1 50V
How do I read the correct capacitance. Or if someone has a schematic what are the values of C1, C11,C47 and C62.
Thank You
The Beaver
Uncle_Victor
Posts: 2
Joined: 15:57, 5 July 2010

Re: KR-4500 Schematics

Post by Uncle_Victor »

Hello Beaver,

I finally got the KR4500 here for repair.
Some cap's are leaky, that's visible.
You can ignore the first line of digits - might be a type indication or production date.
I noticed 3 different types:
A bunch of (you conted them as 20) of 10µF 16V Case B elco's
I found 8x 3.3µF 50V case B elco's in the D/A section
4x 10µF 25V Case C elco's
and 1x 1µF 50V Case B type.
Most of the 3.3µF's are visable leaking - also a few 10µF 25V
I desoldered them and measured them: the 3.3µF are at the best some 10nF with a lousy Q, so they are definitely dead.
The 10µF 16V I tested were all OK, but anyway, while you are busy, replace them.
By the way, in addition to my previous post: don't use a heat gun to desolder them. This are old pcb's, still soldered with the now forbidden lead/tin alloy and quite easy to desolder with a good soldering iron.
I myself use a desoldering tweezer but that might be too expensive for occasional use.
The pcb has signs of corrosion on several places nearby the leaky cap's, but in my case the copper was nowhere completely gone.
Anyway, remove any sign of corrsion - I use a glass fiber pencil for it, you find it at RS under number 514-868 - and measure the corroded track's and especially the via's near them (for those unfamiliar with pcb's, a via is a small hole drilled in the pcb to pass the track to the other side - during pcb production they are metalised so never drill them out)
I ordered the replacement cap's at RS Electronics. I took Panasonic ones; they might be a bit better, in any case they are more expensive.
For those interrested this are the numbers:
3.3µF 50V 536-9966 You need 2 packs of 5
10µF 16V 536-9859 4 packs of 5 needed
10µF 25V 536-9887 1 pack is fine
1µF 50V 536-9922 1 pack
This cost me 11.19€ shipping included (but you need an RS account)

As these eleco's were mostly dead, I'll think it's wise to have a look at the power supply/amplifier module too - I'll do that tomorrow and keep you informed.

Anton, if you are reading this: could you send me a copy of the schematics - might be handy to have in case of trouble.

All the best
Uncle Victor
luc@e2t.eu
Beaver
Posts: 2
Joined: 15:24, 27 August 2010

Re: KR-4500 Schematics

Post by Beaver »

Thank you for the information.
The Beaver
vorschoter
Posts: 1
Joined: 19:53, 8 October 2010

Re: KR-4500 Schematics

Post by vorschoter »

Hello there,

I´ve got the same problem on a KR4500 as Foosy posted in Aug. 2008:

(1. Doing a factory reset (Load + save + Write) reloads factory defaults, but does not solve the problem.
2. The "Tune" and "Oct shift" buttons are always lit and can not be turned off.
3. Pressing the "Tune" button shows: Master Tune 4y3.5Hz. This is not a 'y' but a garbled character.
4. Pressing "Oct shift" shows: Octave Shift
B:_ 11_-2_11_2_11. Some of these are gibberish and pressing the inc/dec buttons do not change anything.)

but what was the result/solution for Foosy? I still changed all Elcos, but no change,
hope someone has an idea...
Vorschoter
xrayjim
Posts: 1
Joined: 15:13, 16 October 2010

Re: KR-4500 Schematics

Post by xrayjim »

I have a friend with the same problem, crackling on the KR4500.
Could someone send me the schematics for reference as I replace the caps?
Thanks,
Jim
Hugoo
Posts: 2
Joined: 22:09, 15 December 2010

Re: KR-4500 Schematics

Post by Hugoo »

I've a KR4500 as well, with the hum-problem (sounds like the lowest frequency of every note is sounding softly, regardless how hard you hit the key, so it is more audible when playing softly). Shortly after the tone is decayed the hum stops as well. The hum is always in the same pitch as the tone you play, so at first I thought it would be a problem in the digital processor or the AD-converter. But it might be the capacitors, so I want to replace them. Since the Elko’s are the most likely to be damaged these are the first I'm going to replace. Other type's cap's won't go bad so easily, so I'll leave them in place.
Jaunnas
Posts: 1
Joined: 20:18, 28 December 2010

Re: KR-4500 Schematics

Post by Jaunnas »

Hi there. Mine 4500 is doing the same. Where can I get a drawing? jaunnas@yahoo.co.uk
Lucille
Posts: 1
Joined: 20:46, 6 February 2011

Re: KR-4500 Schematics

Post by Lucille »

I am experiencing the same problem as Foosey as well. The octaves are way too low and cannot be adjusted. The tune light and octave light are lit and cannot be turned off. I have completed the steps for a factory reset several times with no success. When adjusting the octave, I can use my cursors but the only change is to -2. Roland will no longer support this product and there are no repairmen that have any knowledge of this piano. Please help.
bnuttall
Posts: 1
Joined: 19:31, 11 February 2011

Re: KR-4500 Schematics

Post by bnuttall »

Hello out there
I have a KR-4500 with the right speaker channel dead. After utilizing a signal injector/tracer, I have diagnosed the problem to the main board. I did find a few electrolytic capacitors that were defective so I went ahead and replaced them all. Unfortunately, even after replacing all the capacitors I still have a dead right speaker. Would someone be able to send me or point me to where I can obtain the schematic of this main board?

Much appreciated
Bill
majoday
Posts: 1
Joined: 04:25, 8 March 2011

Re: KR-4500 Schematics

Post by majoday »

I am also new. My wife brought home a KR-4500 and it has bad capacators. I sure could use some schematic and a source for new capacators.

Gary O'Day
majoday@juno.com
huladaddy
Posts: 3
Joined: 07:53, 6 March 2012

Re: KR 4500 behaving strangely (more details)

Post by huladaddy »

Foosy wrote:I wanted to add these additional details:
1. Doing a factory reset (Load + save + Write) reloads factory defaults, but does not solve the problem.
2. The "Tune" and "Oct shift" buttons are always lit and can not be turned off.
3. Pressing the "Tune" button shows: Master Tune 4y3.5Hz. This is not a 'y' but a garbled character.
4. Pressing "Oct shift" shows: Octave Shift
B:_ 11_-2_11_2_11. Some of these are gibberish and pressing the inc/dec buttons do not change anything.

Hope this helps...
I just bought a KR-4500, and unfortunately, it has this exact problem. Seems like a few people have this problem, but I haven't been able to find a remedy anywhere.

I have taken a look at the motherboard, and it looks like the surface mount capacitors have been replaced with electrolytic caps.

Does anyone have a solution to this problem?
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