Recent content by alagami

Hi MK IIB. I haven't had the time for it. Work has been pretty hard on me;). But i've got some time now and this time i eant to get it done. So i just pulled it out and started to work on t. -

Hi there Mark2boogie. It's been a while. Work has taken most of my time. Tat and a couple of Fender Deluxe's. So the Mesa project has been on hold. But its Xmas. Time is on my side;). So i pulled it out and started to look at it again. This time i want it fixed and up and running. I still have...

@mark2boogie thankyou for your info. I allready knew it. Actually I printed your forum-thread, and i printet your good long document about how you got your m2a back to good noisefree shape. And i have read your document many many times. And i am slowly working my way through your...

An update from Denmark;) It's spring here. Weather is good. Wife want me in the garden aka gardening;), so time is limited fixing this amp. And yesterday i was at a concert with the mighty mr. doyle Bramhall II. My biggest influence both guitar'ish and vocal'ish;). But... I've been watching...

Anyone experienced in bias adjusting an old M II A (1979)? I measured my output tubes to around 20 mA which i find kind of low. I used a Bias cable. Actually it was this one https://www.eurotubes.com/store/pc/viewPrd.asp?idproduct=149&idcategory=6. What might be the correct values?

Thank you for your reply @lovetoboogie. I've checked every pot for ground. Everything is fine. Almost no resistance to ground. All good. I bought some cleaner for pots. Every single pot got a treatment. They all work fine. I still need to do the video for you. That'l be a job for the weekend...

The task's i've done for today is: All new caps on power-side. Works fine. Voltage is the same. I put in the missing 470k resistor as mentioned above. Measured voltage around the tubes. No change. The voltage on pin 1 and 6 has dropped. But only very little. Replaced a couple of the ceramic...

A minor update from me regarding this messy board;). I've been focussing so hard on those diodes around v3 tube on the preamp board. Actually i thought that they should not be there at all and were from a mod or something. Lesson learned: Read the whole schematic!!! Those diodes are there...

@lovetoboogie, i started going through the board, one small step at a time. I bumped into my first problem. According to schetatic, im missing a 470K resistor in parallel with the large cap in the preamp board. See my image below. What really throws me off is that i found another image on the...

Thanks a lot for the image. I've been googling for this for days without finding anything usable.

Thank you for your reply @lovetoboogie. I will be going through the board one step at a time. Hell i just bought an old osciloscope;). To answer your question: Yes there is sound through the hum on the lead-channel.

I did swap the tube in V3. Didn't change anything. I do pay attention to what you recommend;-). So this evening i sat down with Uncle Doug (youtube) and went through all the basics. He is so good at learning. Also i got my Fluke177. So i've been reading the plate voltages on all the preamp...

@lovetoboogie - I cannot thankyou enough for sharing your expertise and experience. I am quite good with a soldering iron and actually i am an electrician. Generally i undestand electronics. But i am a newbie in this tube-world. But i am laerning and eager to go deeper. Just ordered a Fluke 177...

Thank you for taking the time to shoot the video. Noise sounds very similar. I can accept some noise when overdriven, but to my ears this is too much. Or is this an acceptable level?

Actually, i found another wrong cap. Across V1a pin 3 - should also be a 22uf, but appears to be 100uf. I wonder who the heck did this. Has he no respect;-).