Studio 22 Prototype

[lovatomi]

Howdy folks, as an "amp man" living in northern California the acquisition of my first Mesa was only a matter of time.I officially joined the club last weekend with a very cool white tolex 85ish mesa boogie studio 22. It seems to be some kind of prototype or something. Unfortunately it doesn't work too well. I bought it with the intention of restoring it and quickly realized that this aint no fender as far as ease of access to the board and online documentation of every nuance of the amp. It's been pretty well mucked with on the inside, but still seemed to work on the "clean channel." not having any real experience with mesa boogies, I am not sure if there is even supposed to be a "clean" channel. Anyway, the "Lead" channel will not engage. I am not sure what the issue is yet. My hope is to try to get everything back to stock and then take it from there.

What would be really helpful would be some gut shots of any early studio 22s people might have. I could not find any previously posted on this forum. I just want to see how it's supposed to look in there. I can tell from the information that I have found that several things are out of place. I will post some pics shortly.

 

[lovatomi]

Here are some photos of the amp in question.

 

[jpdennis]

It does look in need of some TLC. Where in N. Cal are you at? I have several Mesa repair contacts AND there is always Petaluma. As you can see I am in Marysville.

Dennis

 

[RR]

To activate the lead channel, use the footswitch. If you don't have footswitch then plug a cable into the footswitch jack, at the other end ground the tip with the sleeve.

 

[Rob Lockwood]

That looks like a really interesting find. From the state of rust on the chassis it doesnt look as if it was ever plated which I think production ones all were. All those holes in the chassis might suggest that it was a one off test bed for different boards, I would be surprised if they would ever sell an amp like that. I would suggest contacting Mesa and see if they recognise it, there might be some interesting history.

Studio pictures I have seen have the later type green boards like the Mark111. This is the early type board like Mark IIs were built on. Again this might suggest a prototype as you said.

 

[lovatomi]

Thanks guys. @RR, I did try that, to no avail. I think there is something deeper going on. At first I was hesitant to undue all that hard wiring, but after a beer (or two) last night I figured what the hell. It looks like LDR4 is missing, and the place on the board that I have seen in stuff online is not even there. Now that I have the board out I think I will go through with a fine tooth comb and replace all the age-sensitive stuff and test all the other stuff. I am on the fence about what to do with all the LDRs. I am unsure how to test them, and would hate to put everything back together without knowing that they are functional. Might just replace them. I am also particularly confused about how the EQ attaches to the board. This was not really attached where I got it.

The guy I got it from told me that he had recently shown it to Rich Duvall at Mesa, who did indeed think it was a prototype and suggested that the issue was probably some board connections. He also mentioned the goofiness of the transformer placement. The board does say "mesa boogie studio .22 1985 Patent Applied For." I may contact him myself just to see if he can provide any mroe info soon.

And here is the money shot. Not easy to get this one! Hope I can get it back together.

 

[lovatomi]

Images seem to have disappeared. They can also be viewed here:

http://guitartramps.tumblr.com/post/16615739550/mesa-boogie-studio-22-prototype-1985ish

 

[>Photi G<]

It definitely looks like a prototype of some sort. All the holes are for ventilation. I've never seen a .22 with a Mark II-style PCB. I'd have it sent in to be reconditioned. It's not the type of project I'd take on myself.

 

[lovatomi]

"hopeless and unrepairable (which is a very rare occurrence around here - we can fix almost anything - but not this one!"

That was the official mesa boogie response to my inquiry. So I think perhaps i have my work cut out for me!

 

[jpdennis]

... I think perhaps i have my work cut out for me! ...

I remember that there was a thread about someone who was willing to actually take the board and do a PTP or PCB breadboard remake of a .50 Caliber that had fried. I am reading for my interview today - yes I am still unemployed but seeking ...

Maybe you can do a search here or on google, but I think it was on herre.

Dennis

 

[SonicProvocateur]

"hopeless and unrepairable (which is a very rare occurrence around here - we can fix almost anything - but not this one!"

That was the official mesa boogie response to my inquiry. So I think perhaps i have my work cut out for me!

That is indeed an incredibly rare thing to hear from Mesa. As a matter of fact I don't think i've ever heard them say that...but yet again I don't think i've ever seen a prototype surface but maybe once (and I couldn't confirm it myself - it was a Maverick that popped up a year or two ago, and Mesa signed off on it with a custom shop hardwood cabinet...) Your chassis looks alot like the Mark IV/dual rec test bed chassis in Randall's office where he keeps the other protos. Hard to tell from the production versions by looks, but functioning just the same when finished:

Best of luck getting it working! Maybe some other Studio 22 owners can help you blueprint yours and get it working again.

 

[lovatomi]

Thanks sonic, That DOES look it! I think they COULD fix it, just that I couldn't afford to pay them to do it! I know the Xformers work, so there isn't really any reason that with a little (ok, a lot) of elbow grease I cant' figure it out. I have just been going through the schematic piece by piece and checking all components and connections.

 

[Rob Lockwood]

I can see why Mesa would say that. There is probably no schematic for his particular amp and probably no way to be sure what state the circuit was left in. The lead channel problem may be due to a component fault, but it may not be properly 'wired up' either. It seems likely that there was once a lead channel because otherwise what would all those LDRs be doing on there but whether all the components are there now is not certain. I would think that the only way to fix this is to carefully trace out the schematic from the board with component values then compare with a Studio 22 and other schematics and analyse to check whether the circuit on the board forms a workable amp, then going through and testing components. Also with a prototype electrical safety would need to be checked through - there is no guarantee that it was made/tested to the standards of a production amp. This would take many hours time from someone on the design side at Mesa and the cost could be horrendous - with no guarantee that it would sound as good as a production Studio 22 at the end of it.

That doesn't mean it is not fixable though, given enough amp design knowledge, if it is done as a diy project without constraints of having to pay for every hour spent. It does seem to be a prototype amp and if so is unique and a piece of Mesa history. I hope you get it going!

 

[RR]

"hopeless and unrepairable (which is a very rare occurrence around here - we can fix almost anything - but not this one!"

That was the official mesa boogie response to my inquiry. So I think perhaps i have my work cut out for me!

I'm sure they're able to fix it but ...

... Studio .22 price anywhere from $375 to $550 depending on condition. Restoring yours would cost way more than that. Could you imagine the "man-hours" that would go into your Studio .22 and at $65 to $95 per an hour? Then some of those component maybe faulty and could go at any time so they or any technicians could not guarantee a complete trouble-free amp repair.

I'm just guessing but that amp looked like was outside in a car port or somewhere that the weather got to the chassis. I restored a '68 or '69 Fender Princeton and the chassis was similar but not as bad.

Yes you have a big chore a head of you but I'd sure would not discourage you. Matter of fact if the PC board is not salvageable then I would built it point-to-point circuit.

Good luck!

 

[lovatomi]

OK! Here it is:

http://www.youtube.com/watch?v=-fg7p0bLGNY&context=C3def850ADOEgsToPDskIRkAZQCRTDsAofyZb40c33

Guitar is a 1980 SG Firebrand. To me it sounds about like I would imagine it is supposed to sound. I am just playing around with getting the right tube set up. It came loaded with all 12at7s which didn't sound all that great. right now I have all 12ax7 except for a single 12at7 in v2. The only outstanding issue seems to be an excess of feedback at a pretty low volume with the lead channel on. You can start to hear it come through at one point in the video. Otherwise I think it sounds great at apartment levels. The main issues I found when I had it apart seemed to be the switches and the tubes. once I got those straightened out and all the electrolytic s replaced everything seemed to be pretty decent. Just gotta figure out that feedback.

 

[D2dark]

Seem to sound ok !

 

[lovatomi]

Thanks for the reassurance. This amp is VERY quickly becoming my favorite apartment amp. I have had a lot of classic small fender amps (vibro champ, tweed deluxe, 60s deluxe reverb, Princeton Reverb) and for low volume playing at home I like this amp the best. Clean or dirty. The EQ makes it very versatile and can be made to sound just right whether using single coils or HBs. Then again I am sure most of you already knew this!