TornadoTed

drip la2a pcb ver3 (atoms) build thread.
« Reply #20 on: September 29, 2008, 01:33:20 PM »
My components turned up today and I have stuffed the board, it looks fantastic and is so easy with the excellent instructions.
 
I have a few questions if you don't mind answering them. I apologise in advance as I am really new to electronics and some of these may be stupid questions!
 
 
I ordered exactly what was on the BOM. I have several parts left over.
 
1x .022uf Orange Drop, the BOM says 4 but I can only see 3 on the PCB
 
2x 3.9k Resistors, I used one at R24 above the Zero adjust trimmer.
 
1x 6.8k Resistor. I can't find this on the PCB anywhere.
 
1x 1k 1/2 Watt Resistor, I used 7 of them at R20, Grid/1k, R18, Grid 1k, R36, R31 and R32. The BOM says 8, where do I use the other one?
 
2x 1M Resistors. Where do I use these?
 
 
I currently don't have anything at,
 
NE-2 What do I need here?
R7/2k A bit confused as there is no 2k on the BOM.
J2 Do I jump or use a 1k?
J3 Do I jump or use a 1k?
R38/22k Do I jump or use a 22k?
.1 400v C-Cap Ceramic It says optional, should I use something here.
 
The diodes I have are these,
 
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=651-6135
 
Are they ok as I notice they are different to the ones in the instruction manual?
Giant Wafer Studios

www.giantwafer.com


dripelectronics

drip la2a pcb ver3 (atoms) build thread.
« Reply #21 on: September 29, 2008, 03:57:03 PM »
sorry , ive been meaning to update the manual ,
as feed back and questions arrive.

spare .022 was for the power switch rc network (anti pop) if not using the
mallory quench arc .

one of the 3.9 resistors was intended , if you wanted a bit deeper
limiting , (replace R7)

6.8k was a total typo   :oops:

spare 1k , typo  :oops:

2 x 1m resistors are for the ground lifts on xlr in and out.
           (refrence manual)

NE-2 is a NE-2 neon light needed for regulating the meter

i missed the 2k on the bom ,  it is normally a 2.7k for R7

for all the jumps , just use wire , unless stated 1k (grids on 12bh7a)
i add things like this for troubleshooting .  just incase.

r38 , use a 22k (some original  versions have it , some dont)

go ahead and add the x-cap , it can help filter junk out of the
power going in .  (ref. audiophile scourcebook)
some times has no effect what so ever.

your diodes are supposed to be in a TO-220 package,
those say DPAK and are surface mount .

one of the pins is actually connected to nothing ,
in that configuation , the metal base is the cathode ,

best to return them and get a TO-220 package ,

sorry about the leftovers .

g.
g.

[email protected]
(not so good with PM's so dont pm...use email)
la2a ver 3 atoms manual : http://lomayesva.com/la2a_pcb_ver3.pdf
v72 manual : http://lomayesva.com/v72_pcb_manual.pdf

TornadoTed

drip la2a pcb ver3 (atoms) build thread.
« Reply #22 on: September 29, 2008, 06:16:08 PM »
Awesome Greg, many thanks.

I'm loving the build, it is so well laid out. I can't wait to finish it and run some stuff through it.
Giant Wafer Studios

www.giantwafer.com

thehazardharke

drip la2a pcb ver3 (atoms) build thread.
« Reply #23 on: October 31, 2008, 02:26:50 PM »
Got mine today! Thanks greg!!

I'll have pictures posted soon!
thehazardharke

peters

drip la2a pcb ver3 (atoms) build thread.
« Reply #24 on: November 07, 2008, 05:03:35 PM »
I am just getting prepared to build this project, and am wondering if it can easily fit into a 2U (3-1/2") enclosure if tubes are mounted sideways on a length of angle bracket, over the PCB. Am I risking adding significant hum by having jumpers from the board to the sockets (say 2" long)? Would using the DC heaters help?

thanks,
--Peter

parts corrections and clarifications
« Reply #25 on: December 02, 2008, 10:48:44 AM »
The following came from Gregory's replies to a couple of my emails:

On the bottom of the caps page the BOM lists 1) 68pf and 2) 150pf caps. Should be the other way around.

BOM says 1 47uf @25 volt, manual and board say 50 V for C10. 25 will work - only 10V passes so either are OK.

Also in the manual C11 says axial leaded cap, but it's not listed in the BOM. Orange drop works fine.

3 [email protected] ceramic 500 v minimum for optional ground lifts
for the lifts - use poly pro caps like the orange drops - only need 2 for ground lifts - the other was for the x-cap. Do not use the x-cap (it was mainly added for trouble shooting )

Part number discrepancy : the Quencharc snubber listed as Mouser part 504M02QA220 should be 539-104M06QC100.




T-rex

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #26 on: December 02, 2008, 11:31:36 AM »
Sorry for the newb question, but I didnt see this anywhere.  About what is the total cost (approximate) for this project.  I am getting ready to do a Gssl for the experience but I would much rather build an LA2A if the cost isn't too much greater.

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #27 on: December 02, 2008, 11:40:58 AM »
i spent about $900 on mine.  that included the case which was about $350.

- chris

thehazardharke

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #28 on: December 02, 2008, 12:30:25 PM »
spent $400.00 on mine. I got my transformers free.
thehazardharke

T-rex

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #29 on: December 02, 2008, 10:54:46 PM »
Thanks for the info, that gives me a ballpark.

$350 for the case?  That must be one sweet case!


Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #30 on: December 03, 2008, 02:33:57 AM »
sorry, my bad.  it was $350 for 2 cases.  that's still expensive but i needed cases and i'm not much of a metal guy.  but to answer your question, yes they are really nice cases.  the transformers were the next most expensive part.  it's not a cheep project to make from scratch but it's worth it. 

- chris

Whoops

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #31 on: December 25, 2008, 12:04:47 AM »
The Hexfred diodes aren't easy to order in small quantities.
Mouser's minimum order is 715 and Digikey is 1000.

RS only seems to offer the TO-220 package in 600v max. You need 1000v minimum.

Found an alternative here: (pics are illustrative only both are TO220)

http://www.newark.com/vishay-formerly-international-rectifier/hfa06tb120pbf/fast-recovery-power-rectifier/dp/63J6640

http://www.newark.com/vishay-formerly-international-rectifier/hfa08tb120pbf/fast-recovery-power-rectifier/dp/63J6645

These are the specs you need to look for:

type: Diode Hexfred / Fred
Package / Case: TO-220AC
Minimum values: 1000V (Reverse Voltage)  and 1A


if my info is right , this will probably save you some time.

« Last Edit: December 25, 2008, 12:17:43 AM by Whoops »

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #32 on: December 25, 2008, 08:08:54 PM »
I don't know why you couldn't just get it at digikey? I just checked out their site on my iPhone. 462 qty. @ $1.93 each. I thought it was a 220 package...?
"Kind of like going into Safeway at 4 in the morning and chugging a beer in the produce section; been there, done that." - CJ

"We're not making an atomic bomb, just cooking a few electrons." - PRR

"Kind of like going into Safeway at 4 in the morning and chugging a beer in the produce section; been there, done that." - CJ

"We're not making an atomic bomb, just cooking a few electrons." - PRR

Whoops

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #34 on: December 26, 2008, 09:42:55 AM »
Cool,
more alternatives are always better.

Although the price in Newark is $1.14

can't beat that!

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #35 on: December 26, 2008, 05:22:16 PM »
Nice, yes!
"Kind of like going into Safeway at 4 in the morning and chugging a beer in the produce section; been there, done that." - CJ

"We're not making an atomic bomb, just cooking a few electrons." - PRR

buschfsu

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #36 on: December 29, 2008, 08:50:31 PM »
any word on the dc version?
PRR said...
OHM'S LAW. Not as an abstract thing: you should be able to glance at a small circuit and "instantly" know I and V, the way a soccer player glances at the ball and knows the angle and kick

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #37 on: February 14, 2009, 08:41:25 PM »
Well how does the ver3 atom SOUND and stack up to the previous versions?
Not a good sign seeing the thread just kind of drop out!

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #38 on: February 16, 2009, 07:38:11 PM »
WELL????????????!!!!!!!!!!!

rrs

Re: drip la2a pcb ver3 (atoms) build thread.
« Reply #39 on: February 16, 2009, 08:50:09 PM »
Is the manual still available.

Clicked the link and all I got was a pretty girl.  ;D
David Wilson


 

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