Search found 1459 matches

by stokes
Sun Jan 07, 2018 4:28 pm
Forum: Vintage Amps (Before 1991)
Topic: 1985 Mark III replaced filter caps blew fuse
Replies: 8
Views: 4313

Re: 1985 Mark III replaced filter caps blew fuse

It happens.Especially with these current production tubes.Glad you got it sorted out.Looking at the "new" pic,I see a loose red wire hanging by those 220uf's.
by stokes
Sun Jan 07, 2018 2:02 pm
Forum: Vintage Amps (Before 1991)
Topic: 1985 Mark III replaced filter caps blew fuse
Replies: 8
Views: 4313

Re: 1985 Mark III replaced filter caps blew fuse

Although its not absolutely necessary to "pre-form" electros,its not a bad idea,I do it with all new caps.But thats not likely the problem.It is possible that because you changed the main supply caps the voltage downstream to those old caps is stiffer and after a while the extra voltage is shorting ...
by stokes
Sun Dec 03, 2017 6:13 pm
Forum: Vintage Amps (Before 1991)
Topic: Mark III Power Tube and speaker Question
Replies: 6
Views: 3899

Re: Mark III Power Tube and speaker Question

I've no experience with the Canabis Rex,but it would seem to me that the EV would be the most suited for the clean jazz tone you are looking for.
by stokes
Sun Nov 12, 2017 8:06 am
Forum: Mark Series
Topic: Weber spreaker re-cone?
Replies: 2
Views: 1586

Re: Weber spreaker re-cone?

They build great speakers so I would think a re-cone would be a simple job for them.I never had them re-cone one,but when I did my first re-cone years ago when Ted was still around he was very helpful with advice.A Jensen 15".When I got halfway thru I found the coil post was crooked.He had me send i...
by stokes
Mon Oct 09, 2017 9:03 pm
Forum: Mark Series
Topic: Mk. III -- Bias woes. Lil' help?
Replies: 1
Views: 1066

Re: Mk. III -- Bias woes. Lil' help?

Gotta look at what was done when they did the mod.Some techs put a resistor in series with the bias pot.When I do a bias adj mod,I dont use a resistor in series with the pot.As a rule of thumb,I use a pot that is 2x's the value of the stock resistor that is there.i.e if theres a 50k stock resistor,I...
by stokes
Mon May 29, 2017 6:58 pm
Forum: Vintage Amps (Before 1991)
Topic: Redplating problem
Replies: 18
Views: 6788

Re: Redplating problem

Its been a while since I've been in a MKiv,but when I was I dont recall any mistakes in that schem.Most of the iv's I've worked on were cap jobs but a few I did adjustable bias mods and one had a blown 6L6 that took out that screen resistor.I would still replace those 470 ohm screen resistors and se...
by stokes
Mon May 29, 2017 6:30 pm
Forum: Vintage Amps (Before 1991)
Topic: Redplating problem
Replies: 18
Views: 6788

Re: Redplating problem

Did somebody alter things in there before you got it?
by stokes
Mon May 29, 2017 5:26 pm
Forum: Vintage Amps (Before 1991)
Topic: Redplating problem
Replies: 18
Views: 6788

Re: Redplating problem

I would just replace the "open" 470 ohm resistors and pay no attention to the resistors whose values dont seem "right" unless you have other problems after you get those inner sockets to stop red plating.
by stokes
Fri May 05, 2017 7:24 am
Forum: Mark Series
Topic: M II-A correct bias values
Replies: 2
Views: 1469

Re: M II-A correct bias values

That "20ma" you posted means nothing without knowing the plate voltage and calculating the dissipation wattage.Mesa does bias very cold.I like mine to be about 70% of total plate dissipation,which is typical for 6l6GC in class AB.So if plate volts are at,lets say,425vdc I adjust to about 49ma,which ...
by stokes
Wed Mar 01, 2017 7:37 pm
Forum: Vintage Amps (Before 1991)
Topic: Redplating problem
Replies: 18
Views: 6788

Re: Redplating problem

Like I said in my previous post,that 0 volts on your screens is a problem.I suspect the screen resistors are "open" and not letting the voltage thru to your screens.
by stokes
Wed Feb 15, 2017 1:06 pm
Forum: Vintage Amps (Before 1991)
Topic: Redplating problem
Replies: 18
Views: 6788

Re: Redplating problem

That 0 voltage at pin 4 is the problem.Those 220k resistors wont block all the voltage,or as you "prevents an accumulation of charge to sustain a readable voltage",they are "open" and need to be changed.
by stokes
Tue Feb 14, 2017 3:59 pm
Forum: Mark Series
Topic: Mk 2 c+ magic?
Replies: 25
Views: 8855

Re: Mk 2 c+ magic?

A big factor in any amp is where the power tubes are biased.I remember,years ago,Tony Bruno was still developing his line of amps and doing work for the Cars.I had a Gauss speaker he wanted so he agreed to re-tube 3 amps I had in exchange.One of the amps was my 2C+ which I had just gotten from a fri...
by stokes
Sun Feb 05, 2017 8:09 am
Forum: Mark Series
Topic: Mark IIB courtesy outlet blew a tube and fuse
Replies: 1
Views: 982

Re: Mark IIB courtesy outlet blew a tube and fuse

Seriously doubt the courtesy outlet had anything to do with it,just a coincident.The tube blew and took out the fuse,as it should.If you really feel it had something to do with it,just dont use the outlet anymore.
by stokes
Sun Feb 05, 2017 7:59 am
Forum: Mark Series
Topic: Mk 2 c+ magic?
Replies: 25
Views: 8855

Re: Mk 2 c+ magic?

And you aint wrong,at least for you.Tone and feel of an amp is totally subjective.One of the main reasons why I wont repair or mod an amp that requires shipping.
by stokes
Sat Dec 10, 2016 3:46 pm
Forum: Vintage Amps (Before 1991)
Topic: Mark 3 Preamp Problems
Replies: 10
Views: 4347

Re: Mark 3 Preamp Problems

Before you go any further bridge the effects loop with a cable.