Reviews and questions about the entry-level MPC500
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By First Last Thu Jun 08, 2017 9:21 pm
I'm using 3.5mm headphone jack to quarter inch. Same exact setup works perfectly on my 1000 and sound card so I know it's something up with the 500's jack. On the 500 it's super low volume and kinda pops and cracks when I try and find a louder angle - very distorted.

It's always been a little wonky overall and when I opened it up to replace some sketchy buttons I found the last owner had spilled something on it. I'm not good at soldering and don't even have a setup of my own to do it so what can I do to go about fixing this or at least a temp. fix so I can work with the 500.

mpcstuff repairs reliable?
By still_awake Tue Jun 20, 2017 10:54 pm
Ok, first of, fixing this without a basic knowledge of electronics and good soldering experience won't be easy.

The first thing you'll have to do is identify the problem. If the jack you are inserting is good as you mention then you have to figure out what part of the hardware is damaged. The easiest fixes would also be the most probable and are the stereo jack on the mpc or the volume pot. You'll have to check if the main out of the mpc works as expected so you can exclude the potentiometer. In my experience female jacks are rarely prone to failure, but if I had the suspicion of a non working one I would just change it .Generally though, you can always tap into the jack leads and solder a some wires there to check. If I remember correctly the jacks on the 500 are standard Jalco stereo female jacks but you can always use whatever fits inside.

Well after ruling all those out and you still have a non working headphone output, then it is a problem on the pcb. The headphone amp circuit is really simple and easy to debug. there are 4 caps that you should check for leakage, a pair of 220uf electrolitics and a pair of 4700pf. If these are ok then the only thing left would be the tlc084, a TI amplifier which is readily available by mouser for example.

As I said without some knowledge of electronics and good soldering this is kinda impossible.
I hope this was helpful enough. :)