MP2, lights are on but nobody's home

[Version_6]

Well I bought an MP2 with a data error and checked the battery and it was dead. Replaced the battery, powered it back up and got the 'tubes warming up' screen and it got to default user preset 2. Now there's no output and i can't access the menu or anything as the membrane keys don't do anything.

It was in storage for a few years in what seems to be a damp place with some corrosion across the place. Went through and cleared most of it off with a de-oxit pen.

Any ideas where I should start? Hopefully I can get this thing working by myself before shelling out money to get it working.

[rnolan]

Bummer. So was there output initially before changing the battery ? Normal default user preset would be 1 (Marshall patch) after battery change (as all presets are lost when RAM power removed). Normal operation it powers up with the last patch selected (e.g. in may case 112). Do you have any midi pedal for it ? (they shipped/came with an ADA MXC, 1 expression CC pedal and a quad switch). So does the system edit button (far right) not work either ? (i.e. none of the front panel buttons work at all, and did they work at all before battery change ?).
MJMP may have some ideas to check (he's our "under the hood" guru), and there are some other members also with good tech skills and experience.

One thing to try is remove, check/clean, reintsall the EPROM (stores the factory patches and firmware) located front right corner IIRC, should have a sticker on it with the firmware version, last EPROM update was v1.41. Pulling it out and reinstalling won't hurt anything (there's instructions in the mod and schematics area I think) but it's not hard to do (although take electrostatic precautions (power lead plugged in but power off, touch the case to ensure you have same potential difference)).

I'll PM you my phone number if you want to call, happy to chat and help more if I can  :thumb-up:
Cheers R

[Version_6]

Cheers I'll give you a buzz some time tomorrow night then. No, when I got it there was no output, just the bad days message then it would restore to default than the buttons on front would kinda work. After I replaced the battery, I turned it back one and it did the bad data thing again. Turned it off and on again and it powered up and said a midi path error, then one more time turning t off and on again and it went into tube warm up and went into the default patch 2. I have a g system but it's buried under a mountain of other stuff at present because I just moved. I'll see if it changes patches when I get around to getting it out.

[rnolan]

Cool no worries, the extra detail will help trouble shoot (not heard of a midi path error before).  MJMP and others should see this in the interim (he's in Belgium) and may have some ideas, so look out for questions from him and others.

[MarshallJMP]

Did you try the factory presets,since you're battery was dead the user presets are erased,so no sound from these.

[Version_6]

No sound before the dead battery and none after. Can't change the program, it comes up at patch 2 and the membrane buttons aren't responsive now. Connected my mp1 to it via midi to try and change programs that way, no such luck.

[rnolan]

Try pulling the EPROM, clean the contacts/socket and re-install (if for no other reason than to rule it out). If it's not connecting properly the firmware won't load.

[rnolan]

Instructions attached (but are also in the schematics and mods topic)

[Version_6]

Yup did the eprom removal and reinstall, changed nothing. I'm thinking it may be at the point of having to send it for repairs. If it's gonna cost more than $150 I won't bother.

The firmware loads and it's not the final version.

[rnolan]

Well good to rule out that thought bubble... Hang in there a bit, sorry for your frustration BTW.
@MJMP, have you ever come across that Midi path error before ?

[MarshallJMP]

try also pulling the RAM maybe it got corrupted.This way you will reset the RAM.Ram is located next to the eprom (62256)
If that doesn't help try replacing U104 (74LS08),it's just above the eprom and RAM

[Version_6]

Ok pulled and reseated the ram, and the bad data error returned. It went through the 'bad data' scan, then said midi map error, ERR 1. So the ram may be dead and I should go get some and see if that fixes the issue? Also, couldn't find 74LS08 on the board.  :-[

[Version_6]

Never mind. Found it. Since each part is about $1 I'll try replacing them and seeing how I go.

[rnolan]

Cool, I'm hoping you can get it sorted,  :thumb-up:

[Version_6]

One problem solved, another rears its head. So I replaced the ram and also the 74ls08. Once that was done I had control over the patches again and could access functions. Plugged it into something to test it and am greeted by a horrendous modulated hum on all the gain channels and just a mild hum on the cleans. Plug in a guitar and it gets weirder. Once the lead is in, the sound only comes when you connect tip to ground. Plug the guitar in, and the LEDS on the front panel all light up when the volume pot is turned off. No guitar signal coming through at all.

So, what's the next step you reckon?