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Old 17th October 2010, 12:07 AM   #21
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Because you'll have to solder 30+ different connections to the top, to the ground plane, etc. And if the whole thing is masked, it will be a pain to remove the lacker. Plus your board will look all scraped up and ugly. Masking is not good for this kind of an amplifier build. I vote no masking.
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Old 17th October 2010, 12:25 AM   #22
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Quote:
Originally Posted by toufu View Post
Can i get two sets of each board and speaker prot?
me too....
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the best advertisement for a good audio design is the number of diy'ers wanting to build it after all the years....never the say so of so called gurus....
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Old 17th October 2010, 12:53 AM   #23
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For members who want to place order for the boards,
please send your orders as instruction in Post # 6


I am having some progress in the top copper layer now but I am still stuck with the bottom copper layer. The gerber it exports cannot be read by my CAM350 and the program just hangs while reading the gerbers.
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Old 17th October 2010, 05:00 AM   #24
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Default ground plane for pcb

Here is the result of my weekend's work. Sorry it is in pdf format because my print-to-jpg software (Polestar Virtual Printer in case if you want to know or see how it works) is crazy. It sometimes give me the wrong color or some missing lines. Anyone can suggest a better software for that purpose? The grey area (not in your brain) is the top copper plane. Take a look at the 4 red squares.

There are still some problem with the bottem copper layer when exporting to gerbers. Hopefully I can solve that in 2 to 3 days time.

in Post#698, Godfrey talks about the long power ground path. I think I will take that off too (the red and the light green paths) so that every components would go to the power ground (it will be a ground plane after admendment) thru one of their leads and right at where they are located.

I am just wondering what I should do with the signal ground. If it is going to be the way I show in my attached pdf, it will be all (signal and power) connected together, not exactly like what was first intended.

Nagys,
You said you have to solder things onto the ground (power) plane. Just what exactly are those. Can you enlighten us with any photo. As far as I can understand, we are not soldering (or not necessary) things onto the plane itself, just the thrugh pad on the soldering side. Would you be talking about some additionals. Just want to know what is bothering you with a top soldering mask. It will be easy not to include the top soldering mask, it's just unusual to do so.
Attached Files
File Type: pdf tc-1.PDF (123.6 KB, 554 views)
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Old 17th October 2010, 07:30 AM   #25
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bigpanda - Goldmund does not separate signal ground from power ground. As a matter of fact, every single ground point is soldered directly to the ground plane in the Goldmund amplifier, i.e. transistors, resistors, power supply from the bridge/transformer, negative terminal on the speaker output, negative terminal on the signal input, etc. Everything is soldered to the ground plane. Without the solder mask, it would make thing a lot easier, The ground tracks on the bottom of the circuit board are not even needed, but they are nice to have. It depends on how each individual builder wants to use the ground. I will probably only use the ground plane and nothing from the bottom of the circuit board.
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Old 17th October 2010, 12:04 PM   #26
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Hi Nagys,

I will then take off both set of ground traces. Well, I feel less confined now.



All others
Here is the next problem list after the pcb :

1. The outputs
2. BSS71, 74
3. BC182
4. Panasonic relay -- I might have spotted at my supplier but lead time is 21 days and MOQ = 200pcs. But it is not exactly the one Alex drew, it is a TMP 1 Form A, slightly bigger (~1mm on each side) and rectangular. Leg pattern are the same but the position relative to the case is unknown.
5. L1
6. 4W resistors 0.7" pitch
7. 2W resistors 0.5" pitch
8. 4.7p

These are the components I would consider as 'trouble makers'

Still fighting with the bottom copper layer.
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Old 17th October 2010, 04:23 PM   #27
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bigpanda - I would leave the ground traces on the bottom of the PCB. Everything can be soldered to these ground traces, the power and signal ground can be connected with jumpers, and the ground plane can also be connected to the power ground and signal ground. See, this way there are a lot of options, because each individual builder might want to build their amp differently.

If you do take the signal and power ground traces off of the bottom of the PCB, then the ground plane would have to be preferably modified slightly. All the ground places should have the metal going all the way to the components leg, so that it can be easily soldered from the top.

1.) Why is there a problem with the outputs? They're 100% fine the way they are. People should use the plastic type as the metal can original Hitachi 2SK134/2SJ49 are virtually impossible to find. The only thing that potential builders will have to change is the BIAS resistor R23 in Alex's schematic, 330ohm. This resistor will have to be changed to 220ohm, otherwise the MOSFETS might run slightly too hot. Here are all the current equivalent MOSFETS:

Renesas 2SK1058/2SJ162
Renesas 2SK1057/2SJ161
Renesas 2SK1056/2SJ162
Exicon ECX10N16/ECX10P16
Exicon ECX10N20/ECX10P20
Magnatec BUZ900P/BUZ905P
Magnatec BUZ901P/BUZ906P
Magnatec BUZ902P/BUZ907P
Magnatec BUZ903P/BUZ908P

2.) There's nothing you can really do with the Motorola BSS71/BSS74. There's really not an exact replacement available. You can get NOS on eBay and that's where I would suggest people get them from. They're also available from quite a few online electronic parts distributors. You can substitute them with MPSA92/MPSA42 with probably no modifications, but I can't guarantee it. If the originals are not used, then it's up to the individual builder to come up with a creative solution for a replacement and all the necessary changes to the schematic. Also, these transistors DO NOT need a heatsink. No reason for any heatsinks on them, they do not get hot.

3.) BC182B is available everywhere and should not be a problem at all.

4.) Relay replacement I'm still working on and will get back to you shortly.

5.) L1 is a 22 turn inductor. It can be wound in 2 layers around the resistor to make it smaller. I would make a 22 turn inductor, measure the mH, then wind it in 2 layers around the resistor and double check the mH. This shouldn't be a problem whatsoever.

6.) I don't see any problem here.

7.) I don't see any problem here.

8.) 4.7pF capacitors should be small ceramic types. I don't see any problem here either.
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Old 17th October 2010, 05:39 PM   #28
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bigpanda - I thought about this would like to request that you please leave the signal ground, separate from the power ground, plus the ground plane just like in Alex's original PCB design. I think this is important because it's more flexible and will give more options to potential builders. Some people like the signal ground separated from the power ground, those who don't like it can connect it with jumpers. This way it makes everyone happy and gives lots of options when building this amplifier.
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Old 17th October 2010, 05:55 PM   #30
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BC182B is available from Newark/Farnell:

FAIRCHILD SEMICONDUCTOR|BC182B|TRANSISTOR, NPN, TO-92 | Newark.com

Plus hundreds of distributors online and sellers on eBay.
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