[Migroo]

Thanks tomb!

Hopefully i'll get chance to use the pillar drill at work tomorrow!

 

[manaox2]

Over the last three days, my MHMax has been acting up. The power has become uncontrollable with spikes and randomly reaching voltages well about 29v steadily which affects my DB bias also. I'm worried about it and surprised that my power adapter even obtain that kind of voltage. My trimmer can turn it down once it climbs, but it still spikes and drops randomly over a range of 15mv. It started this a little after I decided to change tubes after it appeared I might have a bum one recently. Maybe I wrecked something.

 

[ruZZ.il]

how frequent is it?
Try remove the tubes and measure the voltage.. see it it's stable.
do you have a standoff in the center of the board to keep it from flexing while changing tubes?. Maybe take a look and make sure everything looks good underneath. check around the trimmer too. Is it more stable at some voltage settings than others?
maybe lower your DB bias for a little while while you check things out..

 

[manaox2]

Quote:

Originally Posted by ruZZ.il /img/forum/go_quote.gif how frequent is it? Try remove the tubes and measure the voltage.. see it it's stable. do you have a standoff in the center of the board to keep it from flexing while changing tubes?. Maybe take a look and make sure everything looks good underneath. check around the trimmer too. Is it more stable at some voltage settings than others? maybe lower your DB bias for a little while while you check things out..

I don't have a center mounted standoff in place yet. Everything looks fine underneath and sometimes its stable, but eventually (within 12 hours) it goes back to doing this. The trimmer seems like it isn't mounted quite flush and might be getting a bit of a wiggle. Perhaps I will de/resolder it.

 

[tomb]

Quote:

Originally Posted by manaox2 /img/forum/go_quote.gif I don't have a center mounted standoff in place yet. Everything looks fine underneath and sometimes its stable, but eventually (within 12 hours) it goes back to doing this. The trimmer seems like it isn't mounted quite flush and might be getting a bit of a wiggle. Perhaps I will de/resolder it.

I would suspect the trimmer, too. However, the root of the problem is most likely exactly what Russ said: no center post. Plugging and unplugging the tubes without the center of the board supported can wreak havoc with the board, breaking cold solder joints or worse - tearing traces.

I'd replace the trimmer if you can and go over the bottom of the board with your soldering iron to make sure you have good hot solder joints. Then put a center post in! It's pretty easy - all you need is a standoff, a screw, and enough washers to adjust the spacing so that the standoff just barely touches the desktop/case bottom.

 

[amphead]

Did you try reflowing solder on the bottom of the board? Could be that there is an intermittent cold solder joint aggravated by the board flexing, as others have mentioned.

 

[manaox2]

Quote:

Originally Posted by amphead /img/forum/go_quote.gif Did you try reflowing solder on the bottom of the board? Could be that there is an intermittent cold solder joint aggravated by the board flexing, as others have mentioned.

I'm fairly certain that is the problem, its too bad I am not near my soldering station this week.

I will be settled into my new location in about a month, I will be getting my first paycheck from my new job after graduating college tomorrow.

 

[ruZZ.il]

Congrats!

Keep us updated!

 

[amphead]

Awesome, that certainly is fantastic news!

 

[aaronylee]

Hello everyone!

I finally found the time in medical school to give this a shot. I bought the board with the first group buy a few years ago. I hope it hasn't changed since then...

I had a quick question that I wasn't sure had been asked before or not. Is it necessary to have the LEDs populated under the tube amps? I tried to read the schematic and it looked like it might not affect it, but I wasn't sure.

Thanks everyone!

 

[FallenAngel]

Quote:

Originally Posted by aaronylee /img/forum/go_quote.gif Hello everyone! I finally found the time in medical school to give this a shot. I bought the board with the first group buy a few years ago. I hope it hasn't changed since then... I had a quick question that I wasn't sure had been asked before or not. Is it necessary to have the LEDs populated under the tube amps? I tried to read the schematic and it looked like it might not affect it, but I wasn't sure. Thanks everyone!

Purely cosmetic.

 

[pinkfloyd4ever]

I suppose you're right BMF

(i know there's quotation code, I find the italics hard to read)
"
A couple of recommendations: I would order your trimpots (RA1L/R, RB12L/R, RR3) and big 1000uf electrolytic caps (CA4L/R, CA5L/R, CR1A/B/C/D) from Digikey, because they have Murata trimpots and Panasonic FM caps, which are significantly better than the Mouser alternatives. For the big electrolytics, I'd just order 10 of the 50V since it's cheaper than ordering 4 of the 50V's and 4 of the 35V's (10 because it's cheaper than buying the 8 actually needed). I'd also get CR3A/B/C/D from Digikey. I was told by a career EE (now a project manager) that they're higher quality than the ones listed from Mouser.

Mouser is cheaper without cutting corners on just about everything else, however I'd get the small transistor set (they come matched, which saves alot of hassle, trust me!), output transistors, heatsink mounting kits, tubes, pot, RCA jacks, tube sockets, Vitamin Q's (optional, but most would def recommend them) and power brick (don't forget the cord, it's sold separately) from Beezar. Beezar is a good place to get the Muse ES electrolytics if you want them rather than Blackgates for CA7 & CA9, read up on that on the Max site. "

..and on a related note BMF

, my best-friend-from-college's best friend from high school is the tight end for Purdue, Jerry Wasikowski

 

[BoilermakerFan]

Quote:

Originally Posted by pinkfloyd4ever /img/forum/go_quote.gif [nevermind]

I think you should put some of that info back in the post, especially the component recommendations simply because it's a little daunting to go through
550 pages if your newer to the MAX and it was good advice...

I read the original post in my Gmail alert email.

 

[rhester]

Who has tried the OptiVol with the Max? I am wanting to try one but don't know where to pull power from. Any help without reading way too many pages.

 

[pinkfloyd4ever]

Head-Fi: Covering Headphones, Earphones and Portable Audio - Search Results soloz2 and BoilerMakerFan have, and I believe they got the power from the center LED pads