Substituting components in a MiniMAX build - is this ok?

 I've tried the Vishay-Roedersteins and they're not as good as the Wima's, IMHO.  Since there's only one place you can get the PCB, you might take a look there while you're at it and find the Wima's you need.

If you're talking about one of the CCS resistors, then you should be using the 10K-1K pairs.  Those are almost always in stock (as they are now).  Note that you need two of each, not one.

 Yeah, that one should be fine.

 The 2K, 1/2W resistor used in the power supply should be Mouser Part #71-RN60D-F-2K/R  and it's in stock.  So, I don't understand why you're replacing a substitute with a substitute.

EDIT: OK, you've picked the alternate for the LED resistors - RA5 L/C/R, but you've got the primary part listed and in stock.  You don't need this.

Looks like that first part # is a typo, but at least it goes to the right link (UPW, not UPS).  Still, the replacement you have listed should work fine.  If you want, the UHE's are probably better in this scenario - Mouser part #647-UHE1H102MHD6 (the kits use Panasonic FM's, which are superior to both).

Matt,

Perhaps you should just consider one of these:

   http://beezar.com/oscommerce2/catalog/product_info.php?cPath=37&products_id=125

IMHO, a far, far easier path to success.

jk

Last time Tom did me a great favor by supplying the missing parts that I couldn't order from Mouser. :)
 

Quote:

Originally Posted by Lil' Knight 

Last time Tom did me a great favor by supplying the missing parts that I couldn't order from Mouser. :)
 

Lil' Knight,

Thank you for the fine testimony, but I'm not sure I deserve it.  To be honest, I only supplied those parts for you because you took over the MiniMAX those guys "blew up" and trashed.  So, I was keen to help you restore that one to a working condition.

However, no offense to anyone reading this, but it's not productive for me to regularly supply parts that are out-of-stock at Mouser.  The parts I buy and stock for the MiniMAX are for the kits, only.

Quote:

Originally Posted by MattTS 

Wow, spot-on exactly the help I was hoping to find.  My apologies for fumbling around, this stuff is all still rather Greek to me. Thank you Tom!

 

I'll snag the Wima's in my Beezar order, change those two CCS resisters to the 1.0k/10k (corrected the amounts as well), remove the unneeded resisters, and am hunting for those Panasonic FM's to polish off the list in style.  Is the EEU-FM1H102 from Digi-Key what I'm looking for?

 </snip>

Yes - those are the best (IMHO) for CR1A and CR1B.  However, it looks like they're out of stock on the 1800uf 35V, so I wouldn't worry about DigiKey - maybe just get the Nichicon UHE's I pointed out earlier.  (Two caps are not enough to justify making an order to DigiKey.)

Hmm ... just looking and the UHE's don't come in the right dimensions.  Try these at Mouser - they're fairly close to FM's and appear to be better than the other Nichicons in stock:

http://www.mouser.com/ProductDetail/Nichicon/UHD1H102MHD1TN/?qs=sGAEpiMZZMukHu%252bjC5l7YfSmQquuEPY7uA1Jnz%252bbGYM%3d

Has anyone tried to squeeze anything exciting into the CA9L/R bypass capacitor slots? I was thinking about a pair of .22uf Auricaps (roughly 0.6" x 0.6'); I figure something that small would probably work, but may obscure the trim pots for tube biasing to some degree. I remember reading a post that someone was dropping in a set of Mundorf PIO in the CA9L/R but that was a standard MAX build.

Also, any comments on the differences in sound between the Nichicon and the Elna Cerafine Electrolytics?

Quote:

Originally Posted by HiGHFLYiN9 

Has anyone tried to squeeze anything exciting into the CA9L/R bypass capacitor slots? I was thinking about a pair of .22uf Auricaps (roughly 0.6" x 0.6'); I figure something that small would probably work, but may obscure the trim pots for tube biasing to some degree. I remember reading a post that someone was dropping in a set of Mundorf PIO in the CA9L/R but that was a standard MAX build.

 

Also, any comments on the differences in sound between the Nichicon and the Elna Cerafine Electrolytics?

CA2 and CA9 are not literal signal positions, in the strictest definition.  Rather, the cathode bypass is meant to allow as much headroom as possible from the signal wave coming off of the tubes.  So, differences in caps are not nearly as prominent as they are at the output - CA7 and CA8 - where every bit of the music signal passes through those cap.  Instead, it becomes more a matter of preserving the signal - especially bass - so that none of it is lost.

For instance, smaller caps and some combinations will result in a noticeable loss in bass.  Putting Vitamin Q's or other boutique film caps back there will cause this to happen.  Use of Black Gates at CA2 also resulted in a loss of bass, especially if they were bypassed (by anything).  After years of experimentation, we've settled on the ES and Wima bypasses as the best combination at that position.  It results in the most bass with no detectable loss in highs (at that position).
 

As for the difference between the Elna Cerafines and Nichicon's (assume you mean Muse ES's?).  I once thought the Cerafines were equivalent to Black Gates, but recent reports have indicated they are worse.  I commented at the time that it seemed strange that Parts Connexion was selling them now - because Cerafines were supposed to be out of production.  Some of the small sizes (used on the Bantam, for instance) were/are still available through Handmade Electronics, but they never ran out of stock from the originals.  Maybe there's something wrong with the current Cerafines?  I don't know since I have tried them personally.  IMHO, the ES and Vitamin Q combo at CA7 is about 90% of the quality of Black Gates, so it's pretty close.  The ES's are actually a lot more transparent than Black Gates, but BG's still have better detail, if that makes any sense.  BG's have a bit of a silky-grained fog that doesn't exist in ES's.

The Elna Silmic RFS II's are equivalent to Black Gates, except that they're loads cheaper and don't require the lengthy break-in period (could they get any better?).  Unfortunately, they tend to run huge in size and none of the right ratings will fit in the MiniMAX.  We recommend them as the first, best choice for CA2 and CA7 in the MOSFET-MAX, however.

Quote:

Originally Posted by MattTS 

Well I'm 95% done my soldering (on the pcb), and I'm sizing and preparing a case - last night I attempted to plug in a tube to check exact total height, and ran into an alarming problem; I couldn't get the tube to plug in!  I pressed fairly hard, and heard some very faint "pinging" sounds, and stopped, not knowing what to make of things.

 

When I soldered on the ceramic mounts, I tried to carefully bend the pins out far enough so I could rest them easily in the holes, then press down on the board to finish splaying them out and fully pressed them through the board.  This generated some tension on the pins/arms, and I'm not sure if that would effect things.  I also used just a dab of epoxy on each side of the ceramic circle to glue it back together after drilling out the center pin, then applied a line of epoxy down the center to complete the adhesive work.

 

Should I have to push exceptionally hard?  Should I simply push with vigor and hope things go well?  How hard did you have to push to get yours in?  I've assembled computers from parts, and I probably didn't push quite as hard as I've pushed RAM into slots in the past, but I'm an old hand with computer stuff... this has me being more gentle.

 

-Matt

 

If you drilled and glued the tube sockets back yourself, you should try plugging in an old tube (if you have one) to loosen up the pin clamps on the inside.  Most likely, you got some of the glue onto the pin clamps and inside the ceramic holes.  As long as you let them dry/cure standing straight up, you should be able to loosen them eventually.  The glue would've flowed down away from the tube pin clamps while it was curing/drying.  I turned some sockets upside down once to let the epoxy cure - that was the last time I did that!

Use either a spiral-pushing motion with the tube into the socket, or try rocking it back and forth while pushing down a bit on one side and then the other.  If that doesn't work, go to Harbor Freight and buy some dental picks.  You can usually open the pins up enough to allow you to plug a tube in.  Be careful, though, you can splay out the pin clamps using a dental pick so that they won't "clamp" anymore.
 

The pins that solder into the PCBs will have no effect on the tube pin clamps on the inside of the socket.  That's not the problem.

Here's my build so far. Just waiting for some Elnas to arrive.

Looking good. Did you decide on a case yet?

jk