[ruZZ.il]

SHE IS ALIIIIIIIVE!!

I put in some temporary BDs on the one channel, solved the prob. MJE's in the other.. not sure I care for the imbalance for a little while unless it gets to me. (cant notice it now, it sounds.. mmm.. umm... oooh.. mmmmmmm.. damn ephin good!) till I get more attuned. a middle solder pad from one of those transistors got a little messed.. so I'll actually try keep switching to a minimum.. or something.. for now.. either way, rock on!

Thanks everyone for the support.. and I hope I can be of some to anyone who needs sometime too... meanwhile, I'm enjoying some Tull..

 

[tomb]

Quote:

Originally Posted by amphead /img/forum/go_quote.gif Waiting on (4) 220 ohm resistors and (4) 10 ohm resistors, for RB6 L/R , RB7 L/R, RB2 L/R and RB3 L/R. Could have powered up today, but parts are still 1200 miles away. I found a 30VAC /1000ma walwart. Is that too much?

Expect to dissipate a whole lot of heat in the PS heat sink. 30VDC is max for the MAX, and only with the use of R1, the heater resistor. See the MAX website for Tweaks -> Heater Resistor for details. You will cook the tubes at 30VDC without the resistor.

Voltage Estimate, minimum = ((30 x .9) x 1.414) - 1.4 = 36.8VDC. So, you'll need to burn off about 7VDC x whatever current your MAX is pulling. With BJT's at 50ma, that's a little over 3W, with MOSFETs, that's about 4.5W minimum. You may need a taller heat sink.

 

[babbkutz@comcast]

if you're using the templates for the rear panel on the MAX web site be aware that the use of the fuse requires you move the power entry position (I found out the hard way!)

 

[tomb]

Quote:

Originally Posted by babbkutz@comcast /img/forum/go_quote.gif if you're using the templates for the rear panel on the MAX web site be aware that the use of the fuse requires yow move the power entry position (I found out the hard way!)

Figures ... I'd like to blow away that fuse forever.

 

[babbkutz@comcast]

I checked with Mouser....no luck......anyone have a source? (clear.plain al)

 

[kklee]

Try e-sonic, I've ordered end panels for other Hammond cases from them before.

 

[amphead]

Quote:

TomB: Expect to dissipate a whole lot of heat in the PS heat sink.

Thats really the opposite of where I want to be, so 24V PS it is!

 

[amphead]

Quote:

Originally Posted by ruZZ.il /img/forum/go_quote.gif SHE IS ALIIIIIIIVE!! I put in some temporary BDs on the one channel, solved the prob. MJE's in the other.. not sure I care for the imbalance for a little while unless it gets to me. (cant notice it now, it sounds.. mmm.. umm... oooh.. mmmmmmm.. damn ephin good!) till I get more attuned. a middle solder pad from one of those transistors got a little messed.. so I'll actually try keep switching to a minimum.. or something.. for now.. either way, rock on! Thanks everyone for the support.. and I hope I can be of some to anyone who needs sometime too... meanwhile, I'm enjoying some Tull..

Congrats again! Looking forward to listening to some Tull myself!

 

[Bigguy]

Somebody (scooot) posted a pic showing a fuse mounted in the back panel for outside access like most consumer electronics. That would solve the problem and make another hole to drill.

 

[joneeboi]

Quote:

Originally Posted by amphead /img/forum/go_quote.gif If you are motivated, you could remove the plastic housing around the wallwart plug. In my case, I had to drill out the screws, holding the plastic housing together. Then test for step down voltage after the transformer. If that is bad you will need a new wallwart. If that is good, then move to points on the little pcb that are connected to the output of the transformer. You should find a bad component or even more likely an open in the wires leaving the pcb. In my case I had to splice a broken wire leaving the pcb. Good luck!

Haven't set aside time to really get down to troubleshooting this mother but now that I'm thinking about it a little bit, how in the heck do I reversibly open the wallwart? Surely I can take a hacksaw to it but I still want to use it. Assuming the problem is the wallwart, I've already ordered another one *crosses fingers* but I'd still like to see what's wrong with this one. I always assumed they melted the plastic parts together all around so you couldn't open it and unleash the Pandora's box that lies inside. But perhaps that's what true DIY trailblazing is: discovering that the Pandora's box is a mere treasure chest that someday one will turn into a beautiful case for an amp project. Now, how do I open it? Can it be opened?

 

[ericj]

Quote:

Originally Posted by joneeboi /img/forum/go_quote.gif Haven't set aside time to really get down to troubleshooting this mother but now that I'm thinking about it a little bit, how in the heck do I reversibly open the wallwart?

Sometimes they're glued, sometimes they're solvent welded, sometimes they're ultrasonically welded.

I've cracked open WAY too many of them myself.

First, come to terms with the fact that it's going to get a little messed up. But you'll be able to seal it again.

I usually start by putting it in a vise, with the edge of the jaw about a quarter inch from the seam, and i gently squeeze. Generally, unless I'm squeezing on the wrong side, i'll hear a crack.

This will loosen it up a bit, and sometimes allow you to open it easily after doing all four sides.

Aside from that, It's a matter of prying and jimmying with a flat tool.

Oh, have we mentioned that you can get empty wallwart housings from jameco? so, you have the option of just sawing the damn thing open and repotting it.

If the wart is totally dead, there's a good chance that there's a fuse in it. But there's also a good chance that you overloaded the transformer, and instead of an external fuse it has an internal fuseable link in the winding. In which case it's garbage.

 

[amphead]

Yeah, no step down voltage is definitely a bad indicator. Don't worry about beauty, just get it open and you will learn something. The transformer winding is very thin so be careful not to break it.

 

[tomb]

Joneeboi,
I thought you said a few posts back that you were trying to read DC with your DMM on that AC walwart. If so, it may be fine.

I agree with these other guy's methods about opening it up, but unless you're comfortable working with a transformer and mains wiring, it's not worth your trouble. I use the Jameco walwart cases all the time, but it's to fabricate a brand new walwart with the stuff I want to put it in it. There's only a small chance you can repair your present walwart - assuming there's anything wrong with it. On the other hand, you can get walwarts for the MAX for only $7-$8 anyway.

 

[ruZZ.il]

bumped up Vreg to 28v to keep the temp there down a little.. still got about 3.5v regulating margin. sounds good.. a little cooler.. whats the call on higher voltage anyway?.. 5v reg diff for max ripple filtering?

 

[bperboy]

Would performance increase if I upped the supply voltage and then the tube voltage?