broken 500

hi yall 500'ers i just purchased a broken (lol) mpc500 off ebay,,,the dude said one day it just quit workin,,he says its dam near new,no marks,no blemishes, and he also says "if you can figure it out its a good deal",,,he only wanted 75 bux for it so i bounced on it,,,,,i noticed he had a 2gig card in it,and i noticed that sometimes the mpc trys to boot from the cf,,ive also noticed that sometimes this is the problem with it "turning on",,either way i spent 2 weeks completely restoring a 2000xl so this shouldnt be too much of a task,,,,,,

but what im wanting to know is if anybody has had the same problem or any problems for that matter,that could point me in a direction of where to begin,,,,,

i have enough knowledge to open it up and look at all wires,curcuit boards,connections,the soldering and all that type stuff,,but is there any factory defaults i might need to know about? or common faults?

thanx in advance for all replies!!

it wotn try to boot from the card, but your best bet is to remove the cf card, remove any extra memory and hold the erase/undo key when you power on to reset the machine (this resets it to facotry), if it comes up then try to upgrade the firmware

good luck

phono wrote:it wotn try to boot from the card, but your best bet is to remove the cf card, remove any extra memory and hold the erase/undo key when you power on to reset the machine (this resets it to facotry), if it comes up then try to upgrade the firmware

nice,thanx a lot man..

i look at it like: if it worked once it can work again...just depends on how much i have to invest to get it going..

inflict3 wrote:good luck

thanx,i will definetly let ya know how it goes..

he says the contrst button seemed to be the problem to everything,,,the dude seems super cool he wrote me a frigin essay on how it all happened,,,,but to sum it up,,,he said he tried adjusting the contrast and the screw broke,,,and he says it was while it wasnt plugged in because he didnt want anything to happen,,,then he said he tried to open it up but it looked to complicating to him so he closed it and put it on ebay..

any help with the contrast issue would be well appreciated!!!

How is the screw broken? Can you take a picture of it? I imagining that he stripped out the adjustment pot I guess? Does the screen currently light up or no?
Funny that that would scramble the brains of it.
Did you try to reinstall the os yet from a verified working CF?

yea, you know i adjusted my contrast screw, and it is hella weak, i think its not really a screw head at all, cause it got all dis shaped, and i almost shit my pants,. any info on this would be great, i managed to get it back adjusted where i can see the screen, but i thought i f*cked mine up too, so be careful if you mess with it..

if its jsut the contrast trim pot thats pretty simple

the akai service manual says its this

AL0-20-1103 POT TRIM SMD 10KB SING-TURN RH03ADC14X 1.000 VR1

thats just a 10k trimpot, it looks pretty small, theres a few ways you can do this, either try to find the original part, or find a substitute. I've no idea if thats a linear or log pot but they are so damn cheap you coudl jsut buy both, as long as you can find mini parts.

There is another way to quick fix this, just jumper it with a resistor, you could try a 5k resistor, which would give you about 50% on the dial if it was a liner pot. This woudl be the simplest way since you could just solder the resistor across the legs of the broken trimpot and you wouldnt need to remove the broken part. Of coruse you'd have a fixed contrast but it would work. Resistors are mad cheap, maybe 3 cents each, so you could get a bunch of sizes to find what works best.


Of course i wouldnt attempt any of this unless you have at least basic understanding of soldering etc

hey thanx for all the help people,,and yes,he says its the "pod",,,i havent recieved it yet,it was just sent out this morning,so i should have it by the end of the week,,i will try everything mentioned..my soldering skills are up to par so im not worried about having to solder anything,,,and im also not worried about having a fixed contrast,,to be able to adjust it would be nice,but lets face it,as long as i can see it i can use it,,,as soon as it arrives i will post pics of what he did to it..but you guys were right,he says the pod is broke,,,

here you guys go,,this is the actual letter..

Hey Jason, I can actually tell you exactly what happened.

I actually purchased it only about a week ago from the original owner who hadn't used it much, and it worked fine.

The frustrating thing about the design is the LCD contrast adjustment. It is normally on the back or in a sub menu with every synth I've owned, on the 500 it is located in the battery compartment (weird!)and it's not even a knob, it is a tiny tiny screw adjustment. The screw is really! small, like eyeglass size.

I was careless and used a larger screwdriver than the size required (didn't have one that small). The screw actually broke off.

It's not a pot like you see on other machines, it's something I've never seen before, AKAI was obviously trying to make the machine as cheap as possible and made a pretty horrible descision using the component they did. I tried to open it and get to the board to see if I could unsolder it, I couldn't figure out how to take it apart without being forceful so I decided to screw it back together. Before taking it apart, the screen worked you just couldn't read anything on it because the screw broke off where the contrast was all the way down. After screwing it back together it just would not power on. I have know idea what I did when taking it apart, I literally just opened it and screwed it back together. I might have losened something that just needs to be re-soldered? The board is literally under another board which is under another board; hard to get to and I don't want to make things worse. Since it just stopped working altogether after opening it I think it might be something lose and I don't have enough knowledge about electronics to figure out what it might be. If you can figure it out and get to the bottom board, and find a loose connection, it looks like you might be able to solder in a small plastic pot to replace the one on it, maybe even track down the part that was originally there.
Sorry, ran out of room to type ... anyway, if it's a loosed conection and just the pot you should be able to get it back up and running. The screen should be working just perfectly and I didn't "fry" anything because it was unpowered when I took it apart.

As I said, I just opened it, realized it was tricky to get to the board screwed it back together and it all of a sudden didn't power on. It seems almost certain that I just loosened something and you can re-attach it, replace the pot an get it working.

Hope this helps! I really do hope you get it up and running, it'd be nice to see something positive come out of a frustrating situation for me.

I should be able to get it out Tuesday, Wednesday at the latest, I'll let you know.

Cheers...

Justin


- dnbhallifax

inflict3 wrote:yea, you know i adjusted my contrast screw, and it is hella weak, i think its not really a screw head at all, cause it got all dis shaped, and i almost **** my pants,. any info on this would be great, i managed to get it back adjusted where i can see the screen, but i thought i f*cked mine up too, so be careful if you mess with it..

sorry if i almost made you lose your screen but this helps me out heaps man so thanx,,cause this makes me believe thats all it is,,,and i only paid 75 bucks for the 500,so if this is all it is,thats a hella deal..thanx for the help and sorry if i made you nervous!!

robthom wrote:How is the screw broken? Can you take a picture of it? I imagining that he stripped out the adjustment pot I guess? Does the screen currently light up or no?
Funny that that would scramble the brains of it.
Did you try to reinstall the os yet from a verified working CF?

i cant take paic as i dont have in my possesion until around wednsday,but that is exactly what he said "stripped the pot"
do you know where i could find a replacement for this part?

sonseelye wrote:...,but that is exactly what he said "stripped the pot"
do you know where i could find a replacement for this part?

Probably any electronics joint like radioshack or its analogue wherever your located. Or also mail order from the web, maybe even ebay. Although a storefront would be best IMO so that you could walk in or call and talk to somebody to make sure you get what your looking for.

Phono's suggestions above sound like most of your best options and some good ideas for a home remedy. Personally I'd try the jumper solution first, it sounds much easier and with less chance of doing additional damage. Just grab a few resisters from 3-7k and you can probably even hold them in place with the machine on to figure out which one lands you at the most legible resistance.

One thing that did sound suspicious to me though is that it sounded like he said he opened it up and handled the board and then put it back together and it didn't work. On a PC you can static fry a board if you dont ground yourself before touching it. I certainly hope that didn't happen but it could be something to keep in mind.

Make sure to give us more details after you get a chance to fiddle with it when it arrives.

^^thanx a lot man,lol,now im nervous its fried,i will definetly post up as soon as it arrives because i might need a little guidance,wish the frigin thing was here right now..

if the boards fried,is there a way to tell??

and if thats the case,is it toast??

either way im not to worried,its full of spare parts..thanx again

by the way im in virginia beach,so i have access to radio shack or guitar center(lol)...so i'll take it into radio shack when it gets here..thanx again!!