Did a total over haul on my Mesa Mark III ( Purple Stripe )

[griff10672]

40 years old this year .... it was time .... that and I have been meaning to fix the reverb on this thing forever .

Replaced all the electrolytics including all the tantalum caps even the ones in the EQ ... got rid of all the carbon comp resistors in the power section and replaced them with metal films ..

Had to replace the reverb tank as well as the transformer that drove it ...

Replaced some wiring that looked to crusty for my liking .... also replaced the 40 year old fan ....

Plugged it in finally about an hour ago ...... Man this friggin thing SMOKES !!!!

some before and after shots

finished product

everything that got replaced

 

[Code001]

Awesome work, great job! Looks like it was a total pain in the ass

 

[ChurchHill]

Really nice work!

Wondering what you think of the Purple Stripe as compared to any of the other MkIIIs? I've got a Purple and a Blue. They're both awesome, but my Purple isn't quite as aggressive as my Blue. Part of that I suspect is just the nature of the two versions, at least from what I've read online. Seeing this makes me wonder if it's time for me to overhaul mine, too.

 

[Techdeth]

Super cool . Now do my 3++ greenstripe lol please

 

[griff10672]

Super cool . Now do my 3++ greenstripe lol please

remove the tubes .... box up the chassis and send it over

 

[JimAnsell2]

so any difference in tone for better or worse after replacing the carbon comps? Randall claims that he used certain parts in critical parts of the circuit because it sounded better....(ie carbon comps in the power section) i'm not sure if i buy that or not. Mark III's were like the last fairly easy mark series to work on. I did all this stuff to a simul satillite once, which is basically a mark III with a way stripped back pre amp.

 

[griff10672]

Awesome work, great job! Looks like it was a total pain in the ass

wasn't that bad ..... getting to underneath the board took some careful planning ...

Really nice work!

Wondering what you think of the Purple Stripe as compared to any of the other MkIIIs? I've got a Purple and a Blue. They're both awesome, but my Purple isn't quite as aggressive as my Blue. Part of that I suspect is just the nature of the two versions, at least from what I've read online. Seeing this makes me wonder if it's time for me to overhaul mine, too.

the info on this page was super helpful .... the schematics are pretty spot on .... there's some value differences on some of the components ... but the layout out is spot on ..
https://boogieforum.com/threads/putting-together-a-mark-iii-guide.83605/

 

[griff10672]

so any difference in tone for better or worse after replacing the carbon comps? Randall claims that he used certain parts in critical parts of the circuit because it sounded better....(ie carbon comps in the power section) i'm not sure if i buy that or not. Mark III's were like the last fairly easy mark series to work on. I did all this stuff to a simul satillite once, which is basically a mark III with a way stripped back pre amp.

hard to give a honest answer there .... because I haven't played it in probably at least a year .... and I took that into consideration when I decided to replace them ... I figured .. " I won't remember to know the difference " .... there is one in the pre amp section .... coming off V1 somewhere ... I replaced that one with a more accurate measured NOS one I had ... but the Power related ones I felt a lot better upgrading to more modern metal films ...

 

[JimAnsell2]

i replaced all that stuff and heard ZERO difference. same with the mark IV. i wanted so bad to hear something, but it was the exact same amp. not tighter, or bigger bottom end, not more or less anything. just felt and sounded exactly like i did nothing. I was glad i did it though, i mean we all know those caps have a shelf life, so i don't feel like it was a waste of time or money.

 

[FourT6and2]

Supposedly, carbon comps impart some sort of "mojo" in parts of the circuit with high AC voltage swings, like the power amp. But I've no personally tested this. I think Aiken's website might mention something about it.

 

[griff10672]

Supposedly, carbon comps impart some sort of "mojo" in parts of the circuit with high AC voltage swings, like the power amp. But I've no personally tested this. I think Aiken's website might mention something about it.

yeah .... the Carbon comps in the power section from what I read have a " snap " to them what ever that exactly means .... or how one would interpret that

 

[mentoneman]

i wish you were next door

my III reverb sounds horrid compared to one i played recently. did you order the replacement from Mesa?

 

[c+addict]

Noice! I wish you were my neighbor!

 

[BeZo]

 

[WarHed]

Even replaced the 680R with a proper component, good job

 

[griff10672]

i wish you were next door

my III reverb sounds horrid compared to one i played recently. did you order the replacement from Mesa?

Stock it's not the greatest ..... but there's a simple mod that's mentioned in the thread from the Boogie Board I posted ... makes the reverb a lot better ....

Even replaced the 680R with a proper component, good job

Thanks !!

yeah ..... that fugger gets HOT !

 

[Tone Monster]

Wayne is my electrical Hero!

 

[stratjacket]

That's incredible, nice job !!

 

[skoora]

Is this a 100/60 model (non simul-class)?

 

[7704A]

Supposedly, carbon comps impart some sort of "mojo" in parts of the circuit with high AC voltage swings, like the power amp. But I've no personally tested this. I think Aiken's website might mention something about it.

Something about their voltage coefficient being crap, resulting in added (even-order?) distortion to signals? At least I think that's what I read in Art of Electronics, possibly in The X Chapters. I think I also saw an analysis somewhere that the distortion is not enough to matter in guitar amps, though. It's been a while, if I have a minute I'll try to find it.