dating a mark iii green stripe

[Boogiebabies]

The MK III was discontinued in 1998. Mine is 268XX from 1990.
Ian from the Boogie files has a Green from 1998 in the 283XX range, so they did not really make a lot of MK III Green Stripes. There are probalbly around 1500 or so out of around 13,500 MK III's. Assuming the start of the serial sequence at 15,000 and possibly ending at 28,500 the Green only makes up 11% of all MK III's.

BTW, the Green Stripes use the MK IV Simul OT, 562004.

 

[Boogiebabies]

It should be written in marker on the bottom of the chassis.

 

[Schmoog]

my bet is your green stripe has leftover trannies. mesa never throws anything out. case and point the early no stripes use the IIC+ trannies, and the IV uses the GS trannies (NOT the other way around, its a GS tranny in a mark IV not a IV tranny in a GS). I will validate this theory tomorrow and check the numbers on my 88 Blue stripe. if we've got the same trannys, then you have a relatively early(er) gs with some left over blue stripe trannies

 

[Shep]

my BLUE stripe born 6/88 serial is 2602X...don't know if that help's..

 

[Schmoog]

shep! my 88 (cant remember the month and I dont wanna pull the chassis to see) is 2602x as well. our amps were probably made right next to each other. rock on bro

 

[Schmoog]

I'll take one tonight for you when I get home from work

 

[Boogiebabies]

Mesa's Class A wiring in Simul's was connecting the plate ( Pin 3) to the Screen ( Pin 4 ) by means of the screen grid resistor. If pins 3 and 4 are not connected it's wired as a Pentode. If pins 3 and 4 are connected with the screen grid resistor it's triode. It's still Mesa's version of Class A with the 2.2M resistor on 5 and 8 (1).

If you have a 562003, you have an exact IIC+ Simul OT, just with a different part number. Mine has a 562004 with a late 1989 date code. It does not mean that Mesa did not use up the old stock 562003, but that transformer was available up to a few years ago for Simul upgrades.

 

[Schmoog]

can you change the outer tube wiring in the blue stripe from triode to pentode? or perhaps put in a switch kinda like the mark IV?

 

[Boogiebabies]

Since the MK III's power section is wired PTP, you can do what ever you want with it. The MK IV basically switches out the 2.7K screed grid resistors, but when switched to pentode it blends all the tubes through the 6L6 primary. Any mods to the triode MK III's would basically make a Green Stripe power section. Even though the outer sockets are pentode, they have there own primary on the OT. The MK IV in triode has it's own primary, but when switched to pentode it uses the 6L6 primary for all 4 tubes.

 

[Schmoog]

****. if only I had the long head I could have rich over at time electronics put in a triode pentode switch. that'd be freakin sweet

 

[Shep]

double post

 

[Shep]

Mesa's Class A wiring in Simul's was connecting the plate ( Pin 3) to the Screen ( Pin 4 ) by means of the screen grid resistor. If pins 3 and 4 are not connected it's wired as a Pentode. If pins 3 and 4 are connected with the screen grid resistor it's triode. It's still Mesa's version of Class A with the 2.2M resistor on 5 and 8 (1).

If you have a 562003, you have an exact IIC+ Simul OT, just with a different part number. Mine has a 562004 with a late 1989 date code. It does not mean that Mesa did not use up the old stock 562003, but that transformer was available up to a few years ago for Simul upgrades.

I HAVE A 562003 OP tranny!!!!!!!...mine is a long head...

yeah i might pull her apart later on...then i will get yourt pic..

 

[Schmoog]

mesa's serial numbers are weird. I thought mine was 260xx for some reason. but its 2192x. now I KNOW they didnt make 5000 or so blue stripes. so im conflused. but anyways, I do have the 562003 output transformer. and again I went and measured the plate voltage simply out of morbid curiousity. 493v. GODDAMN I love this amp.

 

[Shep]

do you know wat..

i thought mine was 26oXX to..

but it really was 2302X...There you go..6/88 2302X blue stripe.

 

[Shep]

http://i34.photobucket.com/albums/d139/Shep730/DSC03437.jpg

 

[Shep]

http://i34.photobucket.com/albums/d139/Shep730/DSC03437.jpg

there is the outer tube pic

 

[Schmoog]

Yes. pins 3 and 4 are connected on my blue stripe. I am not gonna post a pic because my cell phone camera is crappy and you cant really tell. but if they are connected them its triode.

 

[Schmoog]

so, in conclusion, you have a green stripe. with a really good output tranny. boogiebabies, do you think it would be expensive to mod the powersection to have one pentode-triode switch for the each pair of tubes (inner and outer). I think meing able to switch each pair between pentode and triode would be an awesome upgrade.

 

[Boogiebabies]

Hard to tell, so is pin 3 & 4 connected?

Thanks to Shep and his palsy, you can see pins 3 and 4 connected by the screen grid resistor.


Tom,

Lay off the coffee before a photo shoot !!!

 

[Boogiebabies]

so, in conclusion, you have a green stripe. with a really good output tranny. boogiebabies, do you think it would be expensive to mod the powersection to have one pentode-triode switch for the each pair of tubes (inner and outer). I think meing able to switch each pair between pentode and triode would be an awesome upgrade.

I'll give you a Mike B. answer.

Well, yeah, kinda, sure, maybe it could be possible. Well, I gotta go, there is a save the earth rally in Santa Rosa. Later !!!