MPC 3000 keeps blowing fuses

I blew the F4 and F2 fuses recently (the ones that came in it from the factory) and I bought new fuses with the same amps. I replaced them all except the F1 fuse and they've all blown, not matter where I put them. The original F1 fuse is the only one that hasn't blown and the MPC will power on, but because of the other blown fuses the machine won't display text or respond to button pressing.
This is a new one on me, never seen this problem before and I haven't been able to find a solution here. Anyone here up on this?

well something is causing them to blow.... dont try shunting past the fuse what ever you do...

you are going to have to go over the components and internals to find out why it's popping fuses. Get that multimeter and the service manual out...

The part that's tripping me out is this: every fuse I've bought and put in it, they blow, but the originals that were in it don't blow at all and I only need one other good fuse.
the voltage and everything is the same. In my 15 years of repairing electronics I've never seen this before and I've never had this issue with my MPC before. 13 yrs without changing fuses is a good lick, though.

KkonEl wrote:I blew the F4 and F2 fuses recently (the ones that came in it from the factory) and I bought new fuses with the same amps. I replaced them all except the F1 fuse and they've all blown, not matter where I put them. The original F1 fuse is the only one that hasn't blown and the MPC will power on, but because of the other blown fuses the machine won't display text or respond to button pressing.

Are you sure it is F4 and F2 that are blowing?

What is F3 doing?

What amps and volts are the fuses that you are using in each fuse position?

You say that the MPC will power on, how do you know it is powered on, what is lighting up or whatever to indicate it is on?

get that service manual... double check the fure model numbers... and dont by those knock off fuses

If the destination country code on the rear of your MPC is A C, then the service manual says you need these ratings for the fuses...

F1 = 1A 125V
F2 = 4A 125V
F3 = 800mA 125V
F4 = 800mA 125V

Are you using these exact ratings for each fuse?

Can you confirm what the indications are that it is actually powering up, and exactly which fuses are blowing?

SimonInAustralia wrote:If the destination country code on the rear of your MPC is A C, then the service manual says you need these ratings for the fuses...

F1 = 1A 125V
F2 = 4A 125V
F3 = 800mA 125V
F4 = 800mA 125V

Are you using these exact ratings for each fuse?

Can you confirm what the indications are that it is actually powering up, and exactly which fuses are blowing?

The lights power on and the backlight powers up, the disk drive boots as well. But no text is on the screen and the buttons don't respond. The F3 blew first and then the rest blew one by one.
I think this issue is, after researching, the F1 has a 8oo mA 125 instead of the 1A it needs. That would explain why that fuse kept blowing on me. I have to get a few 4As and see how that goes.
I tested the hardware and everything else checked out before I went down to one fuse. No burn stains or remnants on anything. Tested all the fuses beforehand as well.

mr_debauch wrote:get that service manual... double check the fure model numbers... and dont by those knock off fuses

LOL Oh naw my man, the place I get them from is a licensed dealer of Bussman fuses, amongst others. no way I'd put bootleg fuses in my LE

Okay I've replaced all the fuses, with the proper ampage. I put 800mA/250 V fuses in the last two spots on the top board and they keep blowing.
This time the screen came on momentarily as the fuses blew (slow blow fuses) and once they went the screen text was gone again.

yeah, you will need to figure out what is shorting or causing the fuses to blow... thank god the machine takes fuses.

I think you probably need someone with some tech skills to troubleshoot it in person.

Seems that something must have failed or shorted out, possibly in the rectifier or regulator in the +/- 12V section of the Power PCB somewhere. If not, then something has failed further within the MPC circuitry, which is drawing too much current from the power supply.

Maybe try disconnecting the thin 2-wire cable from the CPU PCB to the Filter PCB (to remove power from the backlight inverter circuit), and disconnecting power to the floppy disk drive, and turning it on without those connected, in case one of those is faulty and causing the fuses to blow.

Maybe you could try powering it up with the cable from the Power PCB to the CPU PCB disconnected. The MPC would not work at all, but if it is still blowing fuses then there would most probably be a fault with regulator/rectifier section.

Not sure if there is much more troubleshooting that you can do yourself without some electronics fault finding skills and gear, and some circuit level diagnosis.

Also, not sure that they should be slow blow fuses, I think it only shows slow blow for the European voltage versions, not the US voltage version.

Yeah, What simon says... you maybe could narrow down where the issue is.. that is key right there.

Yeah I'm taking it to my electronics guy to have him troubleshoot it. He fixes a lot of vintage amps and receivers so he'll know which way to go with it.

Download the complete MPC3000 service manual, the version with the circuit diagrams, and take it with you, so he has something to work from.

It might make the process quicker and easier for him, and cheaper for you.

I sent it to him as an attachment a few days ago, but I took the liberty of printing it out for him anyhow.