Search results

Hi there, what is the serial number of your Mark IIB? The short answer is that these particular resistors won't be causing any funny noises that you're describing. The resistors that you're looking are on the bias circuit. There are a few variations in the early Mark IIB? From memory though...

Thanks for the comments on your Ace and Studio22. Sounds like the high heat might be normal. I did an experiment the other night with a fan located underneath the power transformer and a thermocouple attached to the outside of the transformer. After one hour the temperature had stabilised to...

Bump - can anyone help me please??

Hi Mark owners, I am completing the restoration of my 60 watt Mark IIB. I have fired it up and it works well and sounds great. I an running Tung sol KT66 which have the same heater current draw as 6L6GC at 0.9A and biased at 40mA (I have installed a bias pot). My only concern is the amount...

I am wanting to buy Mark I/ II/IIB/IIC project or non-working amps for restoration and documentation purposes. I don't really care what the problem is or how rough they are cosmetically - I will restore them to their former glory. I'm in the process of documenting the layouts of Mark I and II...

Interesting. I definitely have reverb on this amp so the mystery continues. I wonder what others have on their IIA or IIB's? Does anyone know how accurate these schematics are? To help me with my rebuild I've actually plotted out the complete layout of the amp and have tried to relate...

Thanks b00g13mk2B, Many thanks for this observation. It seems like the mesa schematics are not very reliable sometimes. I have also seen some anomalies on the bias circuit of my amp when compared to the schematics. Can anyone else confirm this observation of the additional 1 meg resistor on...

I hope you guys can help me. I am restoring a Mark IIB that has had some significant modifications and was in a very bad way when I purchased it. I am restoring it to its original condition. I am carefully going through the circuit against what I see on populated on the PCB and I am finding a...

Thanks Dude2Dude, that's exactly what I wanted. It looks like there is just a 100K resistor from the power rail to pin 1 on V2A which is different to the mark IIB schematic which has a 0.1 uF cap tied to pin 1 as well as two resistors that approximate 100K. Can anyone advise what should I do...

Hi Everyone, I am in the process of restoring a "modified" Mark IIB back to original (serial #5947). I guess that this is a very early IIB. I am having a problem with the V2A area especially the input (pin 1). Mine has a 0.1uF Ruby (Sprague) Orange Drop Cap with a 56K resistor parallel to...

Does anyone know if replacing the 50uF/75V Bias caps on my Mark IIB with 100uF/100V have a detrimental affect or any affect for that matter? I have a lot of trouble sourcing parts where I am based but do have access to F&T 100uF/100V electrolytic capacitors - if I can use these then that would...

Hi again, Would anyone know the current (mA) of the high tension secretary taps (325 vac). I'm assuming it's around 400 mA. Also can anyone confirm the voltage on the bias tap - is it 50 vac? Many thanks again for the help.

Hi Dave, Sincere thanks - that's exactly the info that I needed. I will also need the 50V bias tap and a CT. I will check what the pilot needs - thanks for that advice. I will probably have him wind the primary for 117 VAC, 220 VAC (Thai wall voltage) and 240 VAC (I am an Aussie too so I will...

Hi everyone, This is my first post so please be gentle. I have recently bought my first Boogie, a Mark IIB. I have a number of years of amp building and repair experience on fenders but not so much on Mesas. The IIB is in a bad way and has a blown PT and has been modded by people who don't...