1971 Mark I is in the Shop!!!!!!!

[Monsta-Tone]

One of the local radio DJ's called me up on Saturday. He asked if I would be up for refurbishing his 1971 Mark I!
Of course, the answer was YES!

He brought it up on Saturday. According to him, not much works on it anymore.
Power switch is broken and jumpered inside the chassis.
EQ does not work.
Tone knobs do not work.
Pull functions are noisy.
Etc.....

He gets here and it's serial # is in the mid 500's!
It's the tan tolex with wicker grill. Looks like it's been through Vietnam, Grenada, Panama, Iraq, and then Afghanistan!


I open it up and guess what......
New output transformer. Standard Mesa 100 watt tranny. Wired wrong!
New pots. Looks like my 6 year old son replaced them with a blow torch and a cordless drill!
Some new filter caps. Hanging off of the board and poorly zip tied in place.
GEQ had a broken transistor lead and the input wire fell off.
Preamp circuit has been monkeyed with. Don't know what was done yet, but.....it's full of Chinese capacitors and cold solder joints.

This guy says that he had someone do the work, but I'm betting that he did the majority of it himself!
There is one power tube screen grid resistor that has been changed. I'm really thinking that this is all his amp needed when the OT was replaced and some fool installed a new one so that he could steal the original!

Anyway....
I'll post some before and after pics when I can. This guy is going to be blown away when he fires up the amp he bought in the early 70's and it finally works right after 10 years of sitting in a closet!!!!!!

 

[fishyfishfish]

Pics please!!!.
At least the previous "Modder" is keeping you in business.

 

[zodiac272]

nice, yeah keep us in the loop please!

scott

 

[Monsta-Tone]

I'm really curious to know when it was actually made. Most of the marker on the chassis is faded away.

I just saw a letter that came with a 1976 Mark I (serial # in the high 800's).
Wonder how many they made a year back then?

 

[McBarry]

MT, I've got a 470's serial MkI which is 1976.
Interestingly, a close cousin just went on fleabay from Warpdrive Music in a head -theirs was 4 numbers away from mine.
Mine is export BEFORE the red export voltage panel -ie; all voltages are dymo labels as well.

Hangin' out for pics... but cringing at the description thus far.. sounds like it was at a butchers, not a tech's place..

 

[Monsta-Tone]

Thanks for the help with the date.
The guy says that his brother bought it new from the factory in 1971. Guess his timing is a little off.
Either way, he's had it since the late 70's.
He's not very nice to his gear, as you can tell.

Some of the pics are duplicates, I left them because our camera has a tendency to blur parts of pictures. I thought 2 of each would help.
Some of them didn't get edited apparently too!
http://s257.photobucket.com/albums/hh235/Monsta-Tone/Mesa%20Mark%20I%20A535/

I need some help with the Volumes and the Jacks.
They are so different from the drawings that I can't make out what is going on.
Does anyone have a sketch of what the jack and volume pot wiring should look like?

I've fixed everything but Volume 1, Volume 2, Input Jacks, and the Pilot Light.

I'll have to post some "After" shots once I'm done!

 

[igfraso]

I would say that a Mark I in the mid 500s, must have been produced in 1976.
Keep in mind that, sometimes, serial numbers are a little off between combos and heads.

What surprises me is that Ian's Mark I is in the mid 1100s and mine is in the mid 1200s. Both produced in mid 1977.
Ian's Keef Mark I was made at the beginning of 1977 and its s/n is A804.

So between 1971 and 1976, Mesa produced 750 amps (in 5 years). Then, in only 1 year, Mesa produced another 600 amps?
Something looks very confusing to me.

Just in case it is of help, my Mark I of 1977 (Blackface circuit) has the RP 5A and the PWR 4.
My MkIIA of 1979 has the RP 6A and the PWR 4A.

Best regards.

 

[McBarry]

Monsta, I just got a heap of Solico pilot lights and Carling switches - had to bulk buy.
Happy to help if U want any.
I'll pull my chassis out tonight and get some pics for U - the 2 input jacks and 2 vol pots??

My god, that's some serious wear and weathering of the cab..
But worse is the weathering inside the chassis. God knows what the boards are like.
Hope they haven't absorbed any moisture and screwing with voltages between tracks...

Pics later tonight..
Dave

PS; totally different topic, does anyone know if the Mark reverb trannies 185225 and 550185 are interchangeable, or what the actual difference is??
Cheers.

 

[Monsta-Tone]

Right on, thanks!
What colors of pilots do you have?

The boards don't seem bad at all actually. I found one pin on the farthest right power tube that was not attached. Forget which one now.

I replaced the wanna be Mallory caps in the tone stack and re-built or repaired almost everything already. I always forget how hard it is to get to some of the stuff in those tiny chassis!
I went ahead and replaced most of the wires that were burned from crappy soldering too.
I'll probably fire it up sometime this week if I get the chance! So far, it's the oldest Mesa I've worked on. I see a lot of old Fenders and Marshalls out here, but not many Marks.


I have a few Carling switches in stock, but what models do you have? Just in case I see something interesting!
Thanks for the help with the jacks too! They have a bunch of 1/4 watt resistors soldered to them, but still look original. Not sure what the guy was trying to do.


There is some turd bucket here that steals amp parts and does the most incredibly terrible work repairing them.
I have seen a ton of Blackface Fenders & Plexi out here that have all of the tone caps replaced with Xicons. The majority of them are also suffering from poor quality transformer replacements as well! After I shake his hand for making more work for me, I'll hand his address over to all of his unsuspecting victims I've helped over the years!

 

[McBarry]

Amber and Blue.
Correct amber for the MarkI, IIA, IIB, IIC and Blue for the MkIII.
Also I have the variation amber for the IIA - same colour, but it's not Series18, like the rest of the Solico's.
Switches are Carling with the short actuator, correct for the Mark I,II series. Mk III had longer actuator.
Just put one in my Mark IIB - perfect!

It's late here and early start in AM, so I'll have to do pics for you tomorrow arvo after work, sorry for the delay.
BTW, hunting for a Mesa reverb tranny - 185225, if U have one in yr box of tricks let me know..
DB

 

[Monsta-Tone]

PM sent!

 

[FreeFormFunkified]

PM sent

 

[McBarry]

Hey Monsta, did U end up finishing the Mk1??
Any pics??
How did it turn out??
Dave

 

[igfraso]

Monsta-Tone,

this is what I found in one of the forums.

Model: Mark I
Serial Number: 494
Style: 1x12 Combo
Finish: Tolex (White)
Year: 1976
Date: May 6th

 

[Monsta-Tone]

Right on, thanks!

I told the guy that it was a 1976. He said no F'ing way. Kind of a strange guy. Nice, but definitely out there!

Not quite done with it yet. I took this weekend off and will get back to it next week.
I think all I have left is the input jacks and a new power cord, but I haven't fired it up yet.

 

[SonicProvocateur]

So between 1971 and 1976, Mesa produced 750 amps (in 5 years). Then, in only 1 year, Mesa produced another 600 amps?
Something looks very confusing to me.

You have to remember when Randall started the company at Lagunitas, they were working modding the Princeton/Boogie's out of Prune and building the 130 Bass and 130 Lead heads with noone but his wife, neighbors and Mike for awhile until Randall's wife got acid in her eye and demand got too much for them. I'm assuming they were already in the 3000 Mark I's with just them by the time they got enough employees and they didn't move shop until they were in Pentaluma in 1980.

Btw, this amp seems like one hell of an undertaking. Any early Mark I is a piece of rock history in my book and it's a shame someone would stoop to stealing parts. I hope you get this sucker working right!

 

[igfraso]

SonicProvocateur,
you may be right. I hadn't taken into account the Doghouse.

FWIW, the last Mark I that I have ever seen is a 7/78 with s/n A2213. At that time, they were making approximately 100 Mark I per month.

 

[Monsta-Tone]

I have a clip of this amp back in action. Just need to figure out how to upload it or host it on my website......
Always something to learn! :lol:

 

[domct203]

Hi Andy,
Do you have any new pictures to post?

I'd love to see the amp after you have worked you magic!

Dom