Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: punkykatt on December 29, 2010, 08:09:27 pm

Title: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: punkykatt on December 29, 2010, 08:09:27 pm: 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
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: VMS on December 30, 2010, 03:09:32 am: 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=37742)

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

http://forum.grailtone.com/viewtopic.php?f=4&t=20609 (http://forum.grailtone.com/viewtopic.php?f=4&t=20609)
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: kagliostro on December 30, 2010, 06:02:24 am: 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
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: punkykatt on December 30, 2010, 07:59:26 am: 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
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: kagliostro on December 30, 2010, 08:37:24 am: 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
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: punkykatt on December 30, 2010, 10:17:07 am: 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?
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: punkykatt on December 30, 2010, 10:22:44 am: 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
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: phsyconoodler on December 30, 2010, 10:36:52 am: 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. :smiley:

Remove R101 and R103 from the board.Just clip them out.
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: punkykatt on December 30, 2010, 11:07:15 am: 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.
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: Willabe on December 30, 2010, 11:53:17 am: Quote from: phsyconoodler on December 30, 2010, 10:36:52 am
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. :smiley:

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 :smiley:
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: phsyconoodler on December 30, 2010, 12:11:55 pm: 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.
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: Willabe on December 30, 2010, 12:19:19 pm: Quote from: phsyconoodler on December 30, 2010, 12:11:55 pm
the 'progressive linkage' switching system that mesa patented.

Progressive linkage whatage? :laugh:

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

Thanks, Brad :smiley:
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: punkykatt on December 30, 2010, 03:28:31 pm: 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
Title: Re: Anyone have a schematic for a Mesa Lonestar "Special"
Post by: gordwait on July 06, 2012, 10:19:52 am: 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..