Anyone have a schematic for a Mesa Lonestar "Special"

[punkykatt]

Hello all, I have a Mesa Lonestar Special on the bench. The owner says he has gone through three 5y3 rectifyers in a short amount of time, he said the 2A slo blo fuse popped also. This amp has four El 84`s for 30w with SS rectifyer, the 5Y3 is switchable to run two El 84`s for 15w and also one El84 SE for 5w. Does anyone have access to a schematic for this amp?  Thanks in advance .  Punky

[VMS]

I don't have a schematic, but according to the threads below you either have to use a NOS rectifier tube or clip some 470 ohm resistors. Contact Mesa and they might tell you which resistors to clip.

http://forum.grailtone.com/viewtopic.php?f=31&t=37742

http://forum.grailtone.com/viewtopic.php?f=31&t=50558

http://forum.grailtone.com/viewtopic.php?f=4&t=20609

[kagliostro]

Hi Punkykatt

Mesa Lonestar Special

Special ???

I can give a link for the "Standard" Mesa Lonestar

http://www.mediafire.com/file/khk6hccu9h1xift/boogie_lonestar.pdf

which are the difference between "Standard" and "Special" ??

Kagliostro

[punkykatt]

Thanks VMS for those links. I`ll check for those 470 ohm resisters.
Kagliostro,  the Special runs four El84 power tubes  and has a 5Y3 rectyfier and SS to switch from 30 to 15 to 5 watt power options.  The Standard has  four 6L6`s or El34`s with a 5U4G and SS rectyfier.

Punky

[kagliostro]

Thanks for Infos about "Special" version

----

I think you can try also to put two diodes in series with the rectifier tube

see the attached image from Merlin's site

Kagliostro

[punkykatt]

Thanks Kagliostro for that possibility with the two diodes. With this pcb Im not sure I can do that yet. It looks like I wont be able to "Y" off to pins 4 and 6 on the 5y3.

The links above talk about clipping two 470 ohm resisters to lessen the load on the 5Y3. Cant find them on this unit, it must be the newer version they talk about?

[punkykatt]

Hey Phsyconoodler,  Got your ears on?  You are a Mesa Boogie tech right?  Have you heard of any service bullitens on this amp about the 5Y3 rectyfiers? Thanks in  advance for any help you can give me.  Punky

[phsyconoodler]

Yup.There are two 470 ohm resistors that need to be clipped and then the 5Y3 will last longer.I'll get back in aminute with which ones they are.


Remove R101 and R103 from the board.Just clip them out.

[punkykatt]

Thanks a million Phsyco,  I found R101 and R103, this amp came through with 100 ohm 1w resisters in place of the 470`s, it even says 470 1w on the pcb. I will clip those out because the amp has been eating 5y3`s.  Thank you again. Punky.

[Willabe]

Yup.There are two 470 ohm resistors that need to be clipped and then the 5Y3 will last longer.I'll get back in aminute with which ones they are.


Remove R101 and R103 from the board.Just clip them out.

Why? What were they trying to do/fix with them in? Whats Mesa's mistake? Just wondering.

       
         Thanks,         Brad     

[phsyconoodler]

When you have an amp that has 4-EL84's the current draw is excessive for the 5Y3 so it has to be switched out of the circuit when going to the 15 watt and 5 watt settings.
  It's unclear as to 'why' they need to be clipped but I bet it's a voltage issue with the 'progressive linkage' switching system that mesa patented.There are always revisions to designs that are complicated like this one is.
  Too many bells and whistles for this cowboy.

[Willabe]

the 'progressive linkage' switching system that mesa patented.

Progressive linkage whatage?     

Sounds like something from a car trans. Hey, but what do I know.


              Thanks,        Brad           

[punkykatt]

Progressive linkage, like a Chevy 327 with  three duces , 4 spd tranny, posi traction 411 rear axle in a Chevy ll body. Reminds me of my gearhead days  in the 60`s when gas was cheap, sex was dirty, and the air was clean.  The good ole days.
Punky

[gordwait]

Hey there,
Can someone tell me where R101 and R103 might be?
My Lonestar Special blew a fuse, and a 68 ohm resistor - just after we had a breaker blow on our band in soundcheck.
I haven't made it out to the local electronics shop to test the tubes yet but I'm guessing the rectifier tube went..

None of the resistors on my 'Special seem to be labelled on the silk screen. The caps are but not the resistors..
I can always try to trace back from the rectifier tube pins..