[Firestorm252]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif OK - sounds like you did adequate testing on the trimmer. Also, if you ran the bias up to 80 - 90mV, then you definitely should've gotten heat from QB8R. Sounds like we need some pics.

Just got home from work and here's some old photos and mock-up photos, pre-wiring, pre-biasing and pre-taking the trimmer off. I upped them to the forum galleries so they resized automatically and are pretty messy. If you would like the raw 10MP shots I can up them someplace.

Notes:

• yes, I know that's definitely not a shoulder washer on QB9L. Forgot to account for the LM317, so I used what I had available: motherboard paper washers.
• The Bergquist pad for the LM317 folded over as I handled the heatsink, I went ahead and folded the rest.

I'll try to get some new photos taken particularly an "above" shot, an underside shot, and shots with the rest of the BJT DB in view, but I'm currently having issues with my camera.

Unfortunately this hobby of mine is getting pushed to the wayside as finals week is just two weeks away, so I've not had time to work on it. If I make any headway/troubleshooting progress I'll be sure to post. But I will be ordering a new set of trimmers, 2-3 just to be sure and a Hammond 1455T1601 (I plan to mount using standoffs)

 

[tomb]

Looks like excellent workmanship from here!

Let's hope it was all that trimmer!

 

[BoxOPwn]

Does anyone know where I could buy a stock Lansing DT1 case?

 

[tomb]

Quote:

Originally Posted by BoxOPwn /img/forum/go_quote.gif Does anyone know where I could buy a stock Lansing DT1 case?

Umm ... have you tried Lansing?

 

[ShinyFalcon]

MiniMAX Drawings & Templates

I believe you can order direct from Lansing enclosures, but will have to call or email them.

http://www.lansing-enclosures.com/ma...pak_prices.pdf

 

[BoxOPwn]

I knew you could order direct, but was hoping that was not the only option.

 

[BlingBlingDr]

Got my miniMAX kit from beezar last week and I am getting everything ready to start cracking on this thing next Thursday. Given the small size of the board, will a Weller ST3 .125" X 0.750" ST Series Screwdriver Tip on my iron cause any problems, i.e. be too large?

Thanks!

 

[tomb]

Quote:

Originally Posted by BlingBlingDr /img/forum/go_quote.gif Got my miniMAX kit from beezar last week and I am getting everything ready to start cracking on this thing next Thursday. Given the small size of the board, will a Weller ST3 .125" X 0.750" ST Series Screwdriver Tip on my iron cause any problems, i.e. be too large? Thanks!

Yes - I think you'd do better with a much smaller tip. I use the standard that comes with the Hakko 936 - it's 0.063" (1.6mm chisel). I'm not saying you need one that small necessarily, but it's certainly within the average needed for projects around here.

 

[BlingBlingDr]

Thanks! Just a few more days of class, 20 pages of writing, wisdom teeth extraction, and a final exam before my journey begins. MiniMAX ahoy!

 

[Firestorm252]

Back to report.
Got the new trimmers and tested them before I stuck them in this time. My luck, I got another bad one out of the 5 I ordered

Anyway, it's working great now. Got it setup and biased over the course of an hour or so Friday night. Tube bias still seems to be fluctuating a tiny bit, is that normal for tubes?

Overall sounds great; heard that one of the drummers in Blueman Group - What is Rock? [live] was slightly off in the beginning and a guitar part I've never been quite able to pick out cleanly in Nobuo Uematsu's - Otherworld. I remember at 1AM debating sleep or continue listening

Thanks for the help. I was debating whether to redo an entire channel's DB til tomb corrected me on how RA1R was influencing the circuit.

Now I just need to get the casework done over the holidays and some better headphones in the future... mmm how my starving college student wallet cringes

 

[tomb]

Quote:

Originally Posted by Firestorm252 /img/forum/go_quote.gif Back to report. Got the new trimmers and tested them before I stuck them in this time. My luck, I got another bad one out of the 5 I ordered Anyway, it's working great now. Got it setup and biased over the course of an hour or so Friday night. Tube bias still seems to be fluctuating a tiny bit, is that normal for tubes? Overall sounds great; heard that one of the drummers in Blueman Group - What is Rock? [live] was slightly off in the beginning and a guitar part I've never been quite able to pick out cleanly in Nobuo Uematsu's - Otherworld. I remember at 1AM debating sleep or continue listening Thanks for the help. I was debating whether to redo an entire channel's DB til tomb corrected me on how RA1R was influencing the circuit. Now I just need to get the casework done over the holidays and some better headphones in the future... mmm how my starving college student wallet cringes

So glad to hear you got it working!

Yeah, tubes are sort of like mules - you go one way, they go the other. The bias will hunt, too, especially early on. You should notice, however, that the bias will drop by about 0.1 to 0.2 per hour for about 2-3 hrs - after that, they should be pretty solid. If I'm shooting for 13.5, I usually adjust to 13.7 - 13.8 when the amp is first turned on (well, after 15 minutes or so - not immediatedly after throwing the switch). That usually works out over several hours. However, if the tubes have not been broken in, they'll drop more than that after a couple of hours - perhaps as much as a volt - but that should stop after a day or two when they're broken in.

You'll also find that you can never get them accurate - 13.4, 13.6, etc. That tendency to drop over the first couple of hours means I always set them high, though. Seriously, though, things are not that precise with the tubes - anything from 13 to 15 will sound pretty good.

If you're noticing more of a drop than that over a few hours and after a few days, it's possible the tubes are bad.

 

[H22]

Got Home 3 days ago and what was on my doorstep?
A big-ol-box-o-minimax goodness!

So I took it to work with my iron and during the day in my spare time ( i work out in the oil patch ) i started assebling it, against my better judgement (more on that later).

I purchaced the complete kit with the black gate option, And I was very impressed with the packaging, Top notch.

I also liked how most of the parts were in little labled bags, saved a bunch of time! One thing that was missing was the RB1 (1k) resistors, all those parts and missing 2 little resistors

. Not a big deal, considering how many parts are included I can understand how they might get overlooked.

As I said earlier, I assembled it in spurts in my spare time, so inevitably i mad a couple of mistakes, first and foremost i didnt do enough digging for info when it came time to mount the big dimond buffer transistors. My kit came with the smaller 2SC3422 and 2SA1359 units, and as I was just looking at the pics for a guide i installed them in the wrong location

. Now remounting the outer two will not be all that hard, however the inner two will be a bear. As I mounted them in the upper hole of the heatsink, there is plenty of lead left on them to just clip them off near the PCB and mount them in the lower hole of the heatsink. But getting clippers into the center two with the black gates in place is all but impossible. I may have to de-sodier the caps to get enough access to do it. I could try to de-soldier the trasistors, but this will heat them up so much i am worried it will destroy them....

And another small oversite was I went ahead and installed CA9 (WIMA's) but I notice that it is recomended to leave these unpopulated if the black gates are used in CA7? So should I remove them????

I went ahead and ordered a new set of transistors just in case I damage the ones I have, and I asked for a couple of 1K resistors to boot.


GREAT KIT!!! WELL DONE!, If I had to make any recomendations though it would be a link(s) on the construction page to the various build options (i.e. the transistors/caps etc) just cause I remember whem building it I was following the instructions on the breezar site link, and it didnt say anything about the different mounting positions, I found that the next day when I was on the minimax page..... Again, My bad ,but the easier the info is to find the less idiots like me will be likelly to mess it up

Joe

 

[tomb]

Quote:

Originally Posted by H22 /img/forum/go_quote.gif Got Home 3 days ago and what was on my doorstep? A big-ol-box-o-minimax goodness! So I took it to work with my iron and during the day in my spare time ( i work out in the oil patch ) i started assebling it, against my better judgement (more on that later). I purchaced the complete kit with the black gate option, And I was very impressed with the packaging, Top notch. I also liked how most of the parts were in little labled bags, saved a bunch of time! One thing that was missing was the RB1 (1k) resistors, all those parts and missing 2 little resistors . Not a big deal, considering how many parts are included I can understand how they might get overlooked.

Arrggh! I've been chasing you for a couple of hours - both with posts on DIYForums.org, a PM, and an e-mail:

Sorry about the resistors - PM me with your real name and I'll drop a couple in the mail to you.
Quote:

As I said earlier, I assembled it in spurts in my spare time, so inevitably i mad a couple of mistakes, first and foremost i didnt do enough digging for info when it came time to mount the big dimond buffer transistors. My kit came with the smaller 2SC3422 and 2SA1359 units, and as I was just looking at the pics for a guide i installed them in the wrong location . Now remounting the outer two will not be all that hard, however the inner two will be a bear. As I mounted them in the upper hole of the heatsink, there is plenty of lead left on them to just clip them off near the PCB and mount them in the lower hole of the heatsink. But getting clippers into the center two with the black gates in place is all but impossible. I may have to de-sodier the caps to get enough access to do it. I could try to de-soldier the trasistors, but this will heat them up so much i am worried it will destroy them....

You should not have to cut the leads. Unbolt the transistor from the heat sink, tie a string through the transistor hole. Make a solder blob on the bottom of the board large enough to cover all three pins and stay melted - then pull on the string. Each transistor should drop right out doing that. Be careful with those things - there may never be anymore of that kind again!

Please don't cut the leads and mount them on the lower heat sink holes - they're run much hotter doing that. Follow the procedure above; it works easier than it reads.

Quote:

And another small oversite was I went ahead and installed CA9 (WIMA's) but I notice that it is recomended to leave these unpopulated if the black gates are used in CA7? So should I remove them????

CA9 is the bypass for CA2. CA2 is a Muse ES 1000uf 16V and using Wima's at CA9 are perfect. the Black Gates are only at CA7 and the bypass for them is CA8, which is where you install those two 0.18uf Vitamin Q's.

Quote:

I went ahead and ordered a new set of transistors just in case I damage the ones I have, and I asked for a couple of 1K resistors to boot.

OK - NOW I know who you are!!

Quote:

GREAT KIT!!! WELL DONE!, If I had to make any recomendations though it would be a link(s) on the construction page to the various build options (i.e. the transistors/caps etc) just cause I remember whem building it I was following the instructions on the breezar site link, and it didnt say anything about the different mounting positions, I found that the next day when I was on the minimax page..... Again, My bad ,but the easier the info is to find the less idiots like me will be likelly to mess it up Joe

Thanks for the kind comments. I'll add the link as you suggest.

 

[H22]

Quote:

Arrggh! I've been chasing you for a couple of hours - both with posts on DIYForums.org, a PM, and an e-mail:

Sorry bout that, the DIYforum looked a bit less used than this one, so i posted here as well.......

Thanks Tomb, I will try as you suggested to remove the transistors tonight, then its set-up and listen time ( I will substitute a pair of standard 1K resistors for now till the others show up ) .

 

[tomb]

Quote:

Originally Posted by H22 /img/forum/go_quote.gif Sorry bout that, the DIYforum looked a bit less used than this one ... </snip>

Ha! That's a bit of an understatement.

At least it still operates.