Well, now that the kit has arrived, I suppose its time to start helping each other build this thing. I know at least Stubbadub and myself are doing this. I also know that I don't have much tech experience (can't speak for Stub) so this thread is to help each other and solicit help from those more experienced.

BTW, the help pages are up over at Scott's site now so you might want to wander over there and poke around first.

Basically, the first step is to populate the resistors on the channel boards. Scott has placed these resistors in a separate bag but has not divided them up by Ohm value so the REAL first step for me was to divide them up and check them off of the parts list as I went.

Not being an electronics whiz, I had to look up a color code off of the internet. Some of the colors are hard to see and some of them just plain don't look quite right but in the end I got the quantities on the sheet to match what I had. It is also important to reference Scotts page here because he mentions some extra parts that are included in the kit but aren't necessary. I divided them up and put them in plastic bags with the value marked on the outside so I didn't have to hunt for them later.

This is as far as I have gotten in the first couple of hours. I just wanted to start the thread in case anyone else wanted to chime in.


Jason A.

Populated the resistors on both audio channel boards but haven't soldered them yet. I will probably do that tomorrow over my lunch hour.


Jason A.

Keep us posted!

I won't be able to begin until at least tomorrow night because I don't have an organized work space but tomorrow I'm picking up a desk from work that will get the job done. I hope I can be of some kind of help somewhere down the line rather than just a sponge, but we'll see...

<a href="http://www.sweatydudes.com/forum">The Sweaty Dudes</a>

At work today I was able to solder the resistors onto the two channel boards and solder the first batch of resistors and diodes onto the PS board.

I have run into a couple of problems though:

The next step on the channel boards is to solder the transistors and JFETS, BUT the bag that holds the active devices did not have the heatsinks in it. In fact, none of the bags marked for the channel boards had heat sinks in them. I did find 4 heat sinks in one of the PS bags that don't seem to go to the PS but they are a different shape than pictured and there are only 4 instead of 8 as indicated in the instructions and parts list.

On the PS side, the parts list calls out for a 33 Ohm/1W resistor. After all other resistors were accounted for, all I had left was a 27 Ohm/1W resistor.

Also on the PS side, the parts list indicates 3 100V Bridge rectifiers and 2 1000V Bridge rectifiers. However, the part number for all 5 are the same and all 5 included with the kit are the same. I made the assumption that the 100V was a type-o since a trip to mouser.com says that part number is a 1000V rectifier.

I've got a couple of emails into Scott but he hasn't responded yet. Unless I go ahead and skip these steps (thus not populating from shortest to tallest) I am pretty much at a stand still.

Let me know if you run into the same issues.


Jason A.

[This message was edited by Jason A. on 01-22-04 at 05:34 PM.]

[This message was edited by Jason A. on 01-22-04 at 05:35 PM.]

One thing that I do is have a multimeter at hand to check resistor values as I stuff a PCB. Red & orange can look remarkably similar, especially on 1% resistors.

Helps with final checking as well.

Do you have a schematic to help us out with your questions? Doesnt seem to be one on the Hamptone site......

Peter

quote:

---

Originally posted by Peter Cornell:
One thing that I do is have a multimeter at hand to check resistor values as I stuff a PCB. Red & orange can look remarkably similar, especially on 1% resistors.

Helps with final checking as well.

Do you have a schematic to help us out with your questions? Doesnt seem to be one on the Hamptone site......

Peter

---

Yes, I checked the resistor and it measures out to 27 Ohm.

Scott probably won't post a schematic of the final design. Paying customers only, and all that.

I did get a brief email from Scott saying that the heatsinks I found in the PS bag were in fact the ones to use but that still doesn't explain why I only have 4 and not 8.

I'll keep you posted.


Jason A.

quote:

---

Originally posted by Jason A.:Scott probably won't post a schematic of the final design. Paying customers only, and all that...

---

You mean the circuit in the kit is different than the one in the Tape Op article???!!!

quote:

---

Originally posted by Flatpicker:

quote:

---

Originally posted by Jason A.:Scott probably won't post a schematic of the final design. Paying customers only, and all that...

---

You mean the circuit in the kit is different than the one in the Tape Op article???!!!

---

I am under the impression that some fairly minor changes have been made. I think most of them were like this one mentioned on his website

quote:

---

"1/15/04: There are 4 x 20kohm (R10/R16 x 2 channels) and 4 x1.82kohm (R12/R18 x2 channels) 1/4W resistors in the audio resistor parts bag that are not needed. They are replaced with the select resistors in the active device bag. These were the original design values shown in the Tape Op article. In the development of the micpres, a 2nd source for the 2n5457 JFETs became available which had about 3dB lower gain, which for this circuit was better. The new JFETs required different resistors. Also the 4 JFETs in the kit are all matched for gain, with select resistors to optimize their performance."

---

The thing is that Scott mentioned last time he did something similar he had some people who payed for a complete parts list. Then someone posted the parts list on some newsgroup which made all the other paying customers mad. So I figure I better not be that person. If Scott wants to post something, I'll be happy to spread it around but until he does, I'll keep it to myself.

BTW, I got a response from Scott on my issues:

I mentioned the heatsinks already but have not found out about the 4 vs 8 thing yet.

The 100V was a type-o

The 33 Ohm resistor was indeed changed to a 27 Ohm.

Scott thinks I may have gotten an older rev of the parts list which is causing some of my confusion.


Later,

Jason A.

[This message was edited by Jason A. on 01-22-04 at 08:03 PM.]

SCA has all their schematics, parts list and step by step instructions with tons of pictures right on line! If I was any good at electronics I would just make my own pc boards and save the dough.

-Dusty

Stubbadub,

How many heatsinks for the audio boards did you get? Mine ended up being in the Power Supply Caps bag. They are rectangular instead of cylindrical and kind of look like black flags.

Scott thinks I have an older parts list and is sending me a newer one but I was wondering if you got 4 or 8 heatsinks. If you got 4, did your parts list indicate 4? If so, which ones get the heat sinks?

I was hoping get past this step tomorrow so let me know soon if you can.

Thanks


Jason A.

ya you got bogus instructions because I only had 4 in my bag. Here's where the heatsinks are addressed on mine:

HJFP CHANNEL CARD ASSEMLY INSTRUCTION:

#4 - Install the heat sinks on the 4 NPN transistors (two are darlington, a transistor that actually has two devices connected together to yield a very high beta or current gain). Form the leads to fit in the pcb "tripod" footprint. These leads break very easy, so be very careful not to bend them more than once. Press them into the appropriate places snug, but not tight, against the board. Make certain not to mix up the darlington NPNs with the regular ones. The circuit works with them reverse but not correctly. Again hold them down with tape and solder them in place. Clip the leads. Install two 2N5457 JEFTs per channels; these devices have all been tested and match. If you lose or damage one, our website will provide information on how to test and select them. Since they are only about $0.60, you can buy 10-20 and pick the best ones. Testing and selecting them only requires a DVM, even though we check many parameters.

<a href="http://www.sweatydudes.com/forum">The Sweaty Dudes</a>

Yes, but there are supposed to be 4 per channel and only 4 total were included with the kits. However, Scott has answered my email on the subject and posted a response on his website:

quote:

---

1/22/04: We just realized that only 4 small TO-92 heatsinks were packed in each kit, not 8. This is totally my mistake, sorry. I told our tech to put in 4, I failed to say per channel. I will either order them next day air, or find them locally, and send them to the people who got kits from the first run (I know exactly what kits got only 4, because we photographed and weighed the contents of each bag in each kit). They will come priority mail so you will have them quick. In the meantime install the ones you have on U2/U3 (the NPNs driving the output) of each channel. In reality they aren't even needed (none of the 3 original prototypes had them). Last, the ones in your kit stand vertically and are square (they are in the psu bag), not round like in the HJFP2 prototype (#4) shown below. The square ones you got are spec'd to dissipate more power than the round ones.

---

This is just the information I needed to keep moving.

Hope to make some good progress today but I'm not sure how much I'll get done over the weekend. Saturday is my birthday.

Keep us posted Stubbadub


Jason A.

Update

I only worked on the channel boards at work today but I got:

All the caps on. I might have two of them reversed though. My parts list doesn't match the picture on the website so I might end up unsoldering a couple of them and swapping.

The push switches on.

The XLR connectors on.

Waiting on Scott again to say whether I have those two caps right or wrong. Again, I'm not too sure how much I'll do this weekend but hopefully I can at least get a little done.

BTW, this is really a lot of fun. I'm glad I jumped in.


Jason A.

[QUOTE]Originally posted by Jason A.:BTW, this is really a lot of fun. I'm glad I jumped in./QUOTE]

That's the whole point, isn't it?

Happy birthday mate!

>Scott probably won't post a schematic of the final design. Paying customers only, and all that.

I do respect Scott's decision not to publish the cct's, and his kit so good, what's the point of DIY in this case. I was thinking more of seeing the PSU cct to work out the 33R/27R issue.

Good luck.
Peter

quote:

---

Originally posted by Peter Cornell:
Happy birthday mate!

>Scott probably won't post a schematic of the final design. Paying customers only, and all that.

I do respect Scott's decision not to publish the cct's, and his kit so good, what's the point of DIY in this case. I was thinking more of seeing the PSU cct to work out the 33R/27R issue.

Good luck.
Peter

---

I don't quite understand what you mean by "what's the point of DIY in this case". Scott published a working circuit in TapeOp. By the time he got around to shipping the kits, the circuit had evolved slightly so values may be slightly different than the TapeOp article or even the prototype kit he has pictured on his website (although I admit trying to rectify your rev1 kit to a picture of the prototype can be a bit frustrating since a few things have changed even since then).

Thank you for trying to help me figure it out. I might try to find a website with the copy of the original circuit so I can put them here as a point of reference. I have a hard copy but I'm not sure of the rules about scanning a circulated magazine and posting them on a public forum.

BTW, Scott emailed and said to populate the caps per the parts list and schematic. Also, a new batch of issues are addressed on his website.


Jason A.

>I don't quite understand what you mean by "what's the point of DIY in this case".

Well, my point is that if you had to go out & buy all the bits, it would cost about the same as Scott's kit. Then one would have to start drilling & silkscreening etc, which is a lot of work. All the hard graft is done for the buyer by Hamptone, just assemble the PCB's & put them into the box.

Peter

Yeah, I agree with peter. I think thats part of the reason SCA doesn't care to show their customers step by step instructions and the schematics. Basically you pay them 80 bucks per pc-board. But it would be a lot of hassle for someone just planning on making a few channels, and I'm sure you'd have to get the and spacing just right or the transformers and opamps wouldn't fit. So for 80 bucks a channel you save the time and money it would take to make the cards and you are guaranteed a working product... definetly worth it IMHO.... but if a schematic surfaced in a few months it might "seem" unfair to past customers. I'm sure some DIYers also have expesnive things like transformers and cases that would work fine laying around.

-Dusty

quote:

---

Originally posted by Peter Cornell:
>I don't quite understand what you mean by "what's the point of DIY in this case".

Well, my point is that if you had to go out & buy all the bits, it would cost about the same as Scott's kit. Then one would have to start drilling & silkscreening etc, which is a lot of work. All the hard graft is done for the buyer by Hamptone, just assemble the PCB's & put them into the box.

Peter

---

For me personally, this approach is exactly what I was wanting.

It's no secret that I'm fairly inexperienced with electronic circuits. I wanted something that would help me get my feet wet, learn some of the lower to intermediate things about component and assembly, and come away with a quality product in the end. This fit the bill quite nicely and came along at the right time.

For the record, I am very interested in building one of your Green pres in the near future as well. It's gotten some high marks from other DIYers.

Gotta go. I'm actually getting some time to work on this thing today and I want to take full advantage.


Jason A.