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Author Topic: Just got my hands on an MP-2, need help diagnosing a problem.  (Read 3432 times)

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PrimalScream91

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I just recently acquired an MP-2. I knew it was untested when I bought it and figured "what the hell" right?

I get it home, plug everything in, flip the switch and... Nothing.

Well... Not nothing per-se, the display and the LED's come on, but the display shows a row of boxes across the top, and I get no sound. I assume this could be some form of error code, but I'm unsure of what it might be alluding to.

I'm away from my gear right now but I figured I might as well pose this question to the depot, just to see what the response might be.
« Last Edit: Time Format by PrimalScream91 »
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Guitars: Gibson SG & Marauder, Kramer Pacer Vintage & Striker 100st, Fender Am Standart Strat & 87 HM Strat, LTD EC1000, a few others...
Amps: Blackstar HT40, A/DA MP-1, A/DA MP-2, A/DA B200S

van Sinn

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Do know that my comments below is speculation..

Do the lights come on and stay static, or do they blink on/off? Same to the display, does it come on as shown, or does anything run across it before entering the shown stand-still modus operandi?

If things do not move, I might suggest the cpu isn't running; if so, this could be a dead cpu (unlikely), a dead crystal on the clock circuit, or a power supply problem.
Have you checked and measured the power supply lines?
« Last Edit: Time Format by vansinn »
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MarshallJMP

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The blocks mean that the CPU didn't start. This can have different reasons like Van already said. Now the red leds are indicating that there could be a power supply problem. The 5V seems ok because the lcd lights up.The leds inside work on 5V,so that looks okay. If you want ,maybe we could do a skype meeting to check all the voltages? And maybe check some other stuff?
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PrimalScream91

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Hey guys,

The blocks stay put, nothing else flashes on the screen.

The lights aren't always red either, at one point the Master, Tone, and Graphic EQ lights were green and the others were off. I am unfortunately in the middle of a move and will not be able to dedicate time to address the issue until next weekend. But I wanted to go ahead and throw the problem out here.

Cheers!
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Guitars: Gibson SG & Marauder, Kramer Pacer Vintage & Striker 100st, Fender Am Standart Strat & 87 HM Strat, LTD EC1000, a few others...
Amps: Blackstar HT40, A/DA MP-1, A/DA MP-2, A/DA B200S

van Sinn

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Yep, I'd start with checking the power supply.
With the lid off, you'll see an aluminum rail going front to rear onto which voltage regulators are mounted.
Refer http://www.ti.com/lit/ds/symlink/lm7805c.pdf for the pinout on those.
It's easy: With the regulator facing you, mount/heatsink up, legs down, the output pin is number three - the one to your right.
The regulator referred above is a +12 volt regulator, but all other voltages types, both positive and negative, have the same pin-out.

Using a voltmeter, initially set to 250 volt scale, you should measure:
+5 volt - for cpu and other digital
+15 and -15 volt - for most of the analog circuitry
+24 and -24 volt - for more analog (discreet preeamp, parts of compressor and wah) and negative bias for tubes
+12.6 volt - for tube heaters

There's also a +200 volt line somewhere (actually more tha 200, just don't remember how much) volts - for tube plates
Don't be scared about this, just be careful about not touching anything else that what's required, and only with insulated measurement pins.

Start by checking these voltages - and be aware of the 200+ volt line :whoohoo!: zapp zapp :lol:

Clamp one lead from the meter to chassis, and pin the other one to pin three on each voltage regulator in turn.

And don't bother with the light coming up in different colors; this is just semi-random behavior until other things hs been fixed.
« Last Edit: Time Format by vansinn »
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MarshallJMP

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Well I measure the voltages in a different way, I look for some opamps to measure the 15 and 24V lines.The reason why is if you turn the pcb upside down you can touch the high voltage caps if you don't know what you're doing.So it's safer to measure on top.Let us know when you're ready to do some measuring and we'll see if we can solve your problem.
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rnolan

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Hey PS91, There's one thing worth trying before you measure voltages which I tripped over recently when I changed the display for a new one.  So if by chance someone has changed the display this could have happened.
The new displays start with the black blocks (like you have) and then after 5 or 10 seconds the boot sequence starts (in the display) The original display didn't do this, it just kicked in, no black blocks and slightly faster startup.  When you install the display (and this is what happened in my case), the grey wiring harness that attaches to the display goes through (under) the flat ribbon cable which connects from the PCB to the front button assembly, and then attaches to the plug on the PCB.  When you unplug the harness from the old display, and then attach later to new display, it's really easy to accidentally dislodge the ribbon cable from where is connects to the PCB (it just pokes into a socket thing).  With mine, it looked ok but one end wasn't quite connected/seated properly (so I've accidentally nudged it with the display harness cable).  The result was what you are currently getting (and why I mention it).  So unit went from working to exactly what you have, black blocks, leds no start up.  So checked around and noticed the ribbon cable didn't look quite right, gently pushed it into it's socket and bobs your uncle, all worked again (except now short period of black blocks before normal boot display)
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van Sinn

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His description say .."flit the switch... Nothing", so I think it's fare to exclude a possibly dysfunctional display.

And I agree with MJMP on how to measure.
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MarshallJMP

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When you start up do the green leds in the switches go on one by one?
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PrimalScream91

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When you start up do the green leds in the switches go on one by one?

Yes sir, they do.
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Guitars: Gibson SG & Marauder, Kramer Pacer Vintage & Striker 100st, Fender Am Standart Strat & 87 HM Strat, LTD EC1000, a few others...
Amps: Blackstar HT40, A/DA MP-1, A/DA MP-2, A/DA B200S

MarshallJMP

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Ok so the CPU starts up but the LCD doesn't. Did you check the ribbon cable like R mentioned?
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PrimalScream91

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Ok so the CPU starts up but the LCD doesn't. Did you check the ribbon cable like R mentioned?

I'm not near it at the moment, but that is definitely first on my list of things to check.
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Guitars: Gibson SG & Marauder, Kramer Pacer Vintage & Striker 100st, Fender Am Standart Strat & 87 HM Strat, LTD EC1000, a few others...
Amps: Blackstar HT40, A/DA MP-1, A/DA MP-2, A/DA B200S

nomorepeople

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...best of luck, Primal. 
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PrimalScream91

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Thanks guys! We just finished moving everything Saturday, so I'll be able to address the issue within a few days. I've got boxes in every room of my new house right now and the missus says they take priority. :crazy:
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Guitars: Gibson SG & Marauder, Kramer Pacer Vintage & Striker 100st, Fender Am Standart Strat & 87 HM Strat, LTD EC1000, a few others...
Amps: Blackstar HT40, A/DA MP-1, A/DA MP-2, A/DA B200S

MarshallJMP

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Whenever you're ready, we will be here  ;D
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