PA800 Samplign RAM Replacement

mike123333 · Post by **mike123333** » Thu Mar 08, 2018 4:05 am

Hello - I have my Korg for about a year now and several months ago I started to get a mild distortion of my styles. I have read that the RAM goes bad on this unit. I cannot find a replacement RAM unless I pay allot of money. Has anyone replaced the chips on the memory slot? I know I can get the chips but wanted to know if it is feasible , not feasible from soldering but it working without external programming.

The second question if it can be done, can I just add all the chips to get 256MB? where would I be able to get the software to get the thing o work?

Thanks
MJ

musiccankill · Post by **musiccankill** » Thu Mar 08, 2018 11:33 am

Hello,
Are you getting distortion only on user samples or factory styles have distortion too?
If factory styles have distortion too , it is not the sample ram that is faulty , it is the CPU board..

mike123333 · Post by **mike123333** » Fri Mar 09, 2018 1:27 am

Hello . Thanks for the response. The sound change seems to happen in both the styles that I download and the styles with factory. it seems that the style changes its beat sound, is this what is considered as sound distortion? I play some music with a selected style if I press on a few keys then the style goes to this so called distorted sound, or it happens after 10-15 minutes of playing without keying down several keys.

This is only happening on the styles and not the performance/styles ( piano, sax, violin etc..). if I stop the style from playing after a minute or so if comes back once I hit start, the style plays normal.

Is there a reset button or something I can test t make sure I am diagnosing the issue correctly?

If the CPU board is the issue, is this the Ram chips on the CPU board or a resistor related issues?

Thanks for any help.

mike123333 · Post by **mike123333** » Fri Mar 09, 2018 1:27 am

Hello . Thanks for the response. The sound change seems to happen in both the styles that I download and the styles with factory. it seems that the style changes its beat sound, is this what is considered as sound distortion? I play some music with a selected style if I press on a few keys then the style goes to this so called distorted sound, or it happens after 10-15 minutes of playing without keying down several keys.

This is only happening on the styles and not the performance/styles ( piano, sax, violin etc..). if I stop the style from playing after a minute or so if comes back once I hit start, the style plays normal.

Is there a reset button or something I can test t make sure I am diagnosing the issue correctly?

If the CPU board is the issue, is this the Ram chips on the CPU board or a resistor related issues?

Thanks for any help.

mike123333 · Post by **mike123333** » Sun Mar 11, 2018 2:36 pm

I disassembled the keyboard and tested the resistance of the resistors across the entire board I did fund several resistors that were off by quite a bit my main question is for the array resistor :

the resistor array is the RA123 or 126, the resistance I am getting across the pins is 2.841,6.63,6.61,6.64,3.220 when I switch the leads around I get the reading at the same points of 3.231,6.63,6.61,6.64,2.826. My questions is two fold, first is the resistance out of tolerance , and it could be worse under load, and what would this resistor be called if I need to order another one? I know the marking 332 is a 3.3 Kohm but it is doubling after the first resistor. is the doubling based on the leads layout at tho they are in serires?

I do have several of these resistors on the board, some read good ( around 3.3k Ohms) both way and others have similar reading to what I posted above.

musiccankill · Post by **musiccankill** » Tue Mar 13, 2018 12:43 pm

I have never seen these 3.3K resistor arrays failing.
I thought one time one was wrong but it wasn't.
Most of the times this happen the TG01 needs reflow too (or better , reballing).Not always needed though.Some times its even the communication between the cpu and the TG01...

mike123333 · Post by **mike123333** » Wed Mar 14, 2018 2:42 am

I combed over both the mother and CPU boards. I only found two resistors that did not give good measurements. R12 which is supposed to be 200K I measure 100K, the other is R73 which is supposed to be 10K it measures 4.5K. I need to replace them.

what about the electrolytic capacitors on the CPU board, I was thinking of replacing them, they test fine as to ESR I get 0.14-0.8 on them.

in my previous post on RA123 and RA126 pins 5 and 10- are common so the resistance checks out fine.

Any other thoughts?

musiccankill · Post by **musiccankill** » Wed Mar 14, 2018 8:27 pm

Haven't yet seen any motherboard failing.And motherboard has nothing to do with sound distortion.
Check in service menu what is the error it gives you to have a better idea of what you are searching for to fix...

mike123333 · Post by **mike123333** » Thu Mar 15, 2018 1:05 am

I do not have any errors, its after playing for a while my styles sound get distorted. This is not the main sounds like the piano, or organ, flute etc.., its the styles with drums or chimes etc..

Hope that makes sense. I am going to change those resistors I mentioned on the CPU board R12 and R73.

This could be all in the software acting up, after I change the resistors I will only load the factory styles and see what happens.

I asked if the CPU electrolytic capacitors are a good idea to change since I have it apart, this board sees allot of abuse so the capacitors can be under a lot of loading and temperature rise.

Thanks for your help.

musiccankill · Post by **musiccankill** » Thu Mar 15, 2018 5:03 pm

I wouldn't change the capacitors , except if you suspect them!
Well if after the 2 resistors it is still not working you should be able to see the error by restarting into test mode after it starts distorting the sounds..
Also it could be efx doing it so try disabling them after it starts to check..!

mike123333 · Post by **mike123333** » Fri Mar 16, 2018 12:12 am

Thanks for your response, how do I enter test mode, I did not find anything about it in searches on internet. Also, what is EFX?

Many Thanks,

MJ

musiccankill · Post by **musiccankill** » Fri Mar 16, 2018 4:53 pm

Unfortunately the rules in the forum don't allow sharing of inside info like how to enter the service mode in public.
By EFX i mean EFFECTS!Sorry for not clearing this up earlier.