Classic repair

[rnolan]

Hey John, wow, that looks quite messy .  I think you've identified the problem area.

[Jdm5149]

Yeah. Would like a pic of circuitboard to match up or if anyone knows if this was some kind of mod. I have schematics so I would like to probably just get those parts back to original state.

[rnolan]

Hey John, just need to have one of our Classic owners take the lid off their unit and take some pics for you.

[Jdm5149]

Thanks a lot. No rush 👍👍

[Harley Hexxe]

I'll have to dig one of mine out of the racks they are in to get some pics.

It looks like someone really hacked that one trying to make quick repairs. If I'm not mistaken, that axial cap should have been a radial one.

[Jdm5149]

Much appreciated Harley.  I've started to unsolder that section   I measured that cap at 100v10uf. Gonna try and clean things up a bit.

[MarshallJMP]

Does this help?

@Harley, the classic runs 12V to the heaters, they used the transformer in a different way.

[Jdm5149]

Maybe a pic of opposite side too Harley. Thanks a lot.

[Jdm5149]

Ordered a few parts. Only thing is under the board it seems some pcs were soldered like jumpers   Was this a mod ?  Was circuitboard damaged maybe.  If anyone could take pic of underside that would be great !  Thanks.

[MarshallJMP]

This ok?

[Jdm5149]

Seems like the area.  Have to clean it up while I wait for a few parts I ordered to start.  Thanks !!

[rnolan]

Hey John, wow, your board has ended up way messy compared to the pic MJMP posted (thanks MJMP ).  And what's the deal with the black traces on your PCB? .

Hopefully, when you clean it up and replace all the components to stock (as you are doing ), it will work fine again (my fingers are crossed for you ).

You asked about MP-1 Classic mods, I don't know of any, moreover I have no docs about any.  So whatever has been done to your Classic, it isn't something we are across (others correct me if I'm wrong).  Seems to me, whatever the modder was trying to do, it didn't go as planned and you have purchased the result...

The main reason you would do jumpers etc. is if you had busted a trace or lifted a pad, hey it happens.  So was this a mod (yes but not one we know about, and not particularly well executed IMHO), was the PCB damaged (maybe?? it's pretty messy).  If it is damaged, you may need to do some jumpers to reconnect broken traces/lifted pads as well as replace all the components, and from the pics, it seems a few components were changed.

[Jdm5149]

Yup.  Parts will be here by end of week. Got unit for $100.  Hopefully I can get it going.  I purchased a Avalon 737sp for $200 in need of repair.  Turns out it was a bigger mess than this classic. I rebuilt power supply. Had to replace pots , meter, etc ....  I almost have it 99% but it was a lot of work and learning to get there. I put about 600$ into it so still a good deal. Always wanted an Ada MP1 so hopefully it's just some resoldering and parts.  I did notice some black residual around that area so maybe some traces were damaged and I probably have to trace out when I resolder.  K thanks for all the info so far   I'll keep u guys updated after I install the new parts

[Jdm5149]

Replaced a few parts and still no good. This seems like either something simple or something very hard.  Haha.  With distortion presets I get max volume. Clean has very low output and some hum.  Even sounds a bit phased. Even with chorus off.  Might have to have someone look at it or put in on the shelf for awhile.

[Jdm5149]

Just ordered chip LF 353n.  Maybe replacing will help.  I'll update in a few days.  Thanks