Kerry

Here's another option: http://www.drillbitcity.com/catalogue/product_detail.asp?Tg=100-10W79-70 These are drill bits with 1/8" shafts. They've got lots of other sizes. Get extra... they break if just think about doing something wrong. I use them in my mill on PCBs. EDIT: Ditto on the changed url

The voltage should not drop significantly when you measure the zeners. Most DVM are about 10M resistance. If you are getting the proper current from Q8 and Q17 then you should not notice a drop. If the input voltage is correct >600VDC, then seems like Q8 and Q17 are not set correctly or working properly. Double check that R1 and R39 are both 3K resistors. Also try to measure the voltage drop across them. It should be about 4V. This would equate to approximately 1.3mA of current. My guess is that it will be way low for both, which would point to bad current sources.

Does anyone have the part number for the testpoint connectors? I did a search and couldn't find them. Thx

One other thought. The hFE for each pair (Q4/Q5, Q6/Q7, and Q8A/B ) should be matched when you are selecting transistors. I don't think this will cause what you are seeing, but I know it will throw the voltage off a bit.

The emitters of Q4 and Q5 should sit just above (about .6V) the 10V reference (base of Q4) and the base of Q5. Q4 and Q5 bases (440V) and collectors (225V) should be very close to each other in voltage. Q6 and Q7 are there to split the difference between the output and ground and should likewise sit just above their bases at about 225V. Collectors of Q6 and Q7 should both be below 1V. When you do the measurements, get the voltages of the bases as well for Q4 - Q7. The circuit that Kevin designed should work fine. I wouldn't give up just yet. EDIT: I was trying to clarify the values for Q4 & Q5 collectors.

Check the 10V reference it should be at -10V with respect to the output. Also, what are the voltages at the emitters of Q4, Q6, and Q7 as well as the collectors of Q6 and Q7.

Not a problem Fing.

There's no turning back now We've got 46 assemblies committed so far out of 69 (after I removed the folks that bowed out). I've got some ideas on how to keep the price, but I want to see where we end up first. Thanks Nate, you're always welcome, but we're not going to be in jeopardy.

The 97.21 includes everything (board, relays, resistors, caps, ICs, etc.) including the assembly costs. Shipping costs look like 13.95 to the UK.

We've got about half the payments in with a few folks bowing out. I'm puting this link here so people can easily get to the payment details:

READY TO ORDER OK. I think I've got all the numbers now as close as I can get them. The issue is that the numbers change up and down based on quantity. What I've done is to use 140 boards and 70 assemblies even though the current numbers are a bit higher (I'm guessing there will be some fall out). I'm going to ask that everyone pay up front, because I don't want to get stuck with extra boards/assemblies at $100 a pop. Also, if the number of boards/assemblies go up or down we can settle up based on the final pricing. Here's the pricing. Remember that I'm ordering 3 extra assembled boards, based on the manufactures recommendation on fall out. If all the boards are all good, I will give these extras to Kevin for all his great work. Assembled Boards Parts Total - 49.41 Number of Boards = 140 1 6 Layer Board - 8.93 Number of Assembled Boards = 70 1 Assembly of 70 - 20.15 1 First Article - 3.57 1 Pre-Shipping - 2.14 Subtotal for Assembled Boards - 84.21 3 Extra Assemblies - 10.83 Total not including PayPal & Shipping - 94.18 1 *Paypal Fee - 3.03 Total with Paypal - 97.21 Bare Boards 1 6 Layer Board - 8.93 1 *Paypal Fee - .41 Total with Paypal - 9.34 * I know there is a slight calculation error on the paypal fee, but compared to all the other variables it is pretty much irrelevant. Shipping - USPS Priority (so I can use the same boxes for everyone) There link is: http://www.usps.gov Domestic 2 assembled boards or any number of bare boards - 5.20 Domestic 4 assembled boards - 10.95 For international, please calculate USPS charges and include those in the total. Payment Information Please calculate your total from the above numbers (Boards + Shipping). I'll try to reconcile everything and PM with any issues. My paypal account is: [email protected] Again, I'm asking for everyone to pay up front, so please let's get this done quickly so that we can get the order in. Also, please PM me with your address and the amount you paid including your paypal name so I can reconcile everything. Thanks in advance I'm really looking forward to getting these boards in, but I also wanted to let everyone know it will take about 4 weeks for the boards and 6 - 8 weeks for the assemblies because there are a few interim steps to make sure that everything works before the production. I will keep everyone posted along the way. Lastly, a number of people expressed an interest in ordering the relays. Please PM me with the number of relays you would want. They should be $2.88 per relay based on the quantities. EDIT: I also wanted to remind everyone that since this is a group by and I am not a MOT that there are no warranties, etc. We are paying for electrical testing on the boards and I will be quickly checking the assembled boards before I send them out. We are taking some good measures to ensure that everyone gets working boards, but I just wanted everyone to know what they are signing up for. Thanks again.

Ok. I'm going to get final quotes tomorrow based on the quantities below. I'll find out if we could do some of the boards with the .4" lead spacing foil resistors. If there is a big price difference then, I'm going to recommend doing them by hand. Here's the list were we stand right now: Name - Assembled - Bare Boards Driftwood - 4 - 6 luvdunhill - 0 - 2 ujamerstand - 4 - 0 deepak - 2 - 2 cetoole - 0 - 10 manaox2 - 2 - 0 el_doug - 2 - 0 DouglasQuaid - 2 - 2 jgazal - 2 - 0 Lil Knight - 4 - 0 nattonrice - 0 - 4 kevin gilmore - 4 - 4 chinsettawong - 2 - 0 Kerry - 2 - 4 Fing - 4 - 0 blubliss - 4 - 0 n3rdling - 4 - 0 guzziguy - 2 - 0 Pars - 0 - 2 Nebby - 4 - 0 Flyingsparks - 0 - 4 dwhat - 4 - 0 minivan - 2 - 0 Craig Sawyers - 2 - 4 MASantos - 2 - 0 Vortex - 0 - 10 Beefy - 0 - 4 Samuel - 2 - 0 deadlylover - 0 - 6 MrMajestic2 - 0 - 4 tcpoint - 0 - 2 spritzer - 4 - 0 Shaman - 0 - 2 Horio - 0 - 2 Fitz - 0 - 4 Jezz - 2 - 2 Max - 1 - 0 TOTAL - 67 - 80

With the 50mm caps they touch the lip on the faceplate. You're right, I was concerned about the screws going into the cap. I could cut them down, but if you accidentally put a longer screw in it seems like bad thinks could happen.

I also wanted to add a note on the 680uF capacitors. The BOM specifies a Panasonic cap that is 45mm in height, but the description says 50mm. These caps were unavailable at the time so I went with 50mm caps and they are a bit too tall. I'm going to replace them, but I wanted to make sure everyone still buying parts knows that the max height on the caps is really 45mm.

Thanks. Regarding the glass filled screws, I've only seen them in #6 and up. I just looked on McMaster and they have Tephlon at $3.50 per (ouch!). They have regular nylon, but I also noticed that they now have polycarbonate in size #4 rated to 212 deg F.

I think that Inu also used glass filled nylon srews. He's been running for a while now. It's all within spec, I just wanted more headroom.

News from the build front... I just powered up the PS and everything looks good I took a few shots. First up is the patch to squelch the oscillation. I used Teflon coated wire and tried to run it so it would cross the least number of traces. Here's the money shot of the rails before I mounted the board in the chassis. Note that I actually mounted everything in the chassis before I attached the rails so that everything would fit once the transistors were soldered in. This was recommended earlier in the thread. I ended up with the 7721-3PPS insulating washers, but did have to drill out the IXCP10M90S and MOSFETs with a #28 bit and deburr them. All the transistors / regulators were mounted on aluminum oxide thermal pads (4171G). I was then able to use stainless steel (black oxide coated in my case) hardware with worrying about an electrical breach to the mounting rails. Here's another shot of the mounting rails after it is placed in the chassis. Note that I tested all of the components before I put anything onto the board. I matched the current regulators for the current limiting in each of the four supplies (I'm sure I did not have to do this). Also, I checked the hfe on the 2SC3675 transistors and picked values between 41 and 47. I wanted to keep the higher hfe transistors for the batteries. Before testing the supply I checked the transformers (first ohms then voltage). Everything from SUMR came in just fine. Said a prayer and powered on just the positive rail. Everything checked out. Next I disconnected the positive rail and checked just the negative rail. Wow, that worked too Finally, I applied power to both the positive and negative rails and everything check out. Note that the -260 volts is a combination of the 500, 60 and 300 supplies on the negative rail. I've still got to scope the supply to make sure that there are no oscillations, but I'm not too worried about that. Not done yet, but I wanted to thank everyone for posting their issues and solutions on the thread. It really made a big difference for me.

I've done the heat sinks by hand and with my mill. Both are not easy. By hand is actually a lot faster for me, but less accurate. Even if I have highly aligned center taps for each hole, the drill bits still wander a bit. I find it easier if you drill the part you will mount first (side rails, heat sink mounting rail) and then secure them to the heat sink and drill on the drill press to start the holes (about 1/8" deep). A lot of what I do is by feel and I've had a lot of experience (first with woodworking and now with aluminum) so I'm able to get away with this. The mill on the other hand perfectly places the holes, but I've never been able to perfectly align the heat sinks in the fixture (even with 45 minutes of prep time). I need to rethink the fixture I use for a heat sink. The time here is in preparing the CAD and then testing on the mill. Alignment takes real time too for me and my mill is pretty slow. Using a CNC mill takes lots of experience and I've got a lot of learning still. I think I will mill a template out of 3/16" aluminum plate next time and secure that to each heat sink (something FPE could do for you). Secure it to the heat sink and use a drill press. This will be much more accurate for me and in the end faster. Tapping holes by hand is as much artistry as it is technique. First time was a disaster, but I'm pretty good with it now. I don't really enjoy it since it is very time consuming. I have a real respect for the CNC milling work Kevin did on the T2 chassis.

Sorry Craig. I saw that in your earlier post, but my mind isn't the steel trap it used to be

I love what you did with the current limiters. Very slick

It looks like the the assembled boards will come in between $76 (1% MELF) and $95 (.1% IRC Thin Film). Both of these boards are the 24K versions. Right now I am leaning to the .1% IRC, but I'm open. I'd also have to check if PCBNet can do the assembly with the MELF resistors onto the 1206 pads. I sill need to to get some final pricing based on current quantities, but I think I am close. Regarding the foil resistors that Craig is looking into, there may be an option to have a small number of boards assembled with this BOM. I will need to check this once resistor choice is finalized. @Craig - You might want to look into 24K version. There seems to be better availability, even over a 25K version. I am going to review the traces on the board to make sure it looks OK, but would like someone else to jump in here and lend a hand. Can't be too careful

Nice build! Congrats. Yeah. You'll want to hear some high-end Stax headphones with that. Start saving

PLEASE SEE POST FOR THE LATEST COUNTS. Here is an updated list. Seems to be stabilizing now. Name - Assembled - Bare Boards grawk - 4 - 0 Driftwood - 4 - 2 luvdunhill - 0 - 2 ujamerstand - 4 - 0 deepak - 2 - 2 cetoole - 0 - 10 manaox2 - 2 - 0 el_doug - 2 - 0 DouglasQuaid - 2 - 2 jgazal - 2 - 0 Lil Knight - 4 - 0 nattonrice - 0 - 4 kevin gilmore - 4 - 4 looser101 - 4 - 0 chinsettawong - 2 - 0 Kerry - 2 - 4 Fing - 4 - 0 blubliss - 4 - 0 n3rdling - 4 - 0 guzziguy - 2 - 0 Pars - 0 - 2 Nebby - 4 - 0 Flyingsparks - 0 - 4 morphsci - 4 - 0 dwhat - 4 - 0 minivan - 2 - 0 Craig Sawyers - 2 - 4 MASantos - 2 - 0 Vortex - 0 - 10 Beefy - 0 - 4 Samuel - 2 - 0 deadlylover - 0 - 6 MrMajestic2 - 0 - 4 tcpoint - 0 - 2 spritzer - 4 - 0 Shaman - 0 - 2 Horio - 0 - 2 TOTAL - 76 - 70

The plan is to run the primary assembly using the reasonably priced resistors. It will likely be possible to also have a portion done with a different BOM.

Before assembly.