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Old 15th March 2012, 10:51 AM   #31
AndrewT is online now AndrewT  Scotland
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There is no provision for an output Zobel.
Use the locations of R1 and the speaker terminal to fit an R+C Zobel.
R1=2r0 to 10r
Speaker terminal=47nF to 220nF.
Add the other half of the Thiele Output Network, the R//L, off the PCB. R=2r0 to 10r L=0.5uH to 1.5uH
Insert a thick copper wire in this pad first, The top end of R1, nearest the output PIN.
Attach R1 to the copper wire.
Take the speaker output from the top end of R1. Attach the speaker wire to the copper wire. I suggest you fit the speaker wire on the bottom side.
You could bend over the top side of the copper wire to lie on top of the output PIN. Solder this connection. But fit a temporary tab heatsink next to the package since quite a bit of heat will try to travel along this PIN during soldering.
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Last edited by AndrewT; 15th March 2012 at 10:54 AM.
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Old 15th March 2012, 10:59 AM   #32
AndrewT is online now AndrewT  Scotland
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There is no RF input filter.
Add a cap to the legs of R5 on the bottom side. Lay the cap flat against the PCB. Trim off the long resistor legs after you have soldered on the cap. Crf=220pF to 1nF
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Old 15th March 2012, 02:42 PM   #33
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Default Better PCB pictures.

Hi guys:

I am posting better, sharper pictures of the two sides of the PCB boards...

Thank you.
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File Type: jpg DSC01015.JPG (937.7 KB, 876 views)
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Old 15th March 2012, 03:24 PM   #34
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Default 2 sides of PCB in the same picture.

Here is another one with the two sides of the PCB in the same frame.
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Old 15th March 2012, 04:21 PM   #35
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AndrewT:

I really appreciate your help, it is more than obvious the high level of knowledge you possess in this matter, and it is very nice to see that you, and most others here, are so willing to share it.

Now, what you write here I have to read few times before I start digesting what you mean because my level of knowledge is the equivalent to 1st grade elementary school and you guys are all PhD.

Please tell me if this is what I need to get to do what you recommend in the two PCB's:

2X 1.5uH axial lead inductors.
4X 10 Ohm resistors
2X 220nF capacitors (What type????)
2X 1nF capacitors (What type????)

Thank you.
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Old 15th March 2012, 04:22 PM   #36
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I forgot to add the 2 pieces of thick copper wire to the list above, one for each board, correct?
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Old 15th March 2012, 05:55 PM   #37
AndrewT is online now AndrewT  Scotland
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I would buy a small range of components, probably in quantities of 10s if I were starting out.

Now I tend to buy in 100s and multiple values of the cheaper components.

Think about changing the BOM to
100 10r 600mW 1% metal film resistor
10 47nF 50V, or 63V, or 100V, cheap film capacitor
10 100nF ditto
10 220nF ditto
100gm or 500gm reel of 1.2mm diameter enameled copper wire.

I see 4 pads connected to the bottom side common ground.

Look and see that C4 -ve pin is connected to the common ground.
If you are building a single channel or monoblock then this connection demands that the Main Audio Ground (MAG) must be on the PCB.

If you want the MAG to be elsewhere or you intend to have more than one channel in the chassis then that C4 must be cut from the common ground.
Carefully cut the three trace bridges. Leave the pad intact. The Signal Ground will now be made at the GND terminal next to the IN terminal.
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Last edited by AndrewT; 15th March 2012 at 05:58 PM.
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Old 16th March 2012, 04:20 PM   #38
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Default Cuts on C4 (-) pictures.

Andrew:

It took me a long time to realize what you were saying. I had to do some research and luckily I found another thread about the same issue in the same exact board where you instructed another guy to do the same, and he was very fast to get the idea and very nice to include pictures, that helped me a lot.

Please check my pictures now and tell me if this is right, it should be according to that previous thread I mention above. I used a Dremel with a cutting wheel, it was very easy, I was extremely careful not to ruin the board, but it only took two seconds at the most to isolate the pad with very light pressure.

I used my multimeter to measure continuity from the modified pad to GND OUT, GND IN and the V- GND V+. The pad used to show continuity in ALL GND pads before the cuts, now it only shows continuity with GND IN, is that correct?.

Thank you very much, Andrew, after googleing and browsing for more information regarding this mods, I realized that you have helped many people, that's very nice of you.

I have some more questions, but I'll save them for later, I just want to make sure I did this right.

Thanks again.
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Old 16th March 2012, 04:26 PM   #39
AndrewT is online now AndrewT  Scotland
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oops.
You nearly cut through the input trace.

Look at your pics. You can still see the three tiny copper bridges.
These are what should be cut. Not the whole plane in that area. Next time it'll be easier.
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Old 16th March 2012, 04:50 PM   #40
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Did I ruin the PCB's?

I did it this way because in that previous thread you suggested not to do it so closely to the pad to avoid damaging it.

Even though you can still see the three little bridges, the pad is now totally isolated from V- GND V+ and GND OUT, there is only continuity between the pad and the GND IN. Is this correct?.

This cuts may look huge in the picture, but I applied very light pressure, just enough to isolate the pad from the GND OUT and DC GND, they are long because the only cutting wheel I have is like 25mm in diameter, I guess I could've done a much better and precise job using a much smaller cutting wheel, also my eyes are not as good as they used to be, these PCB's look big in the pictures but they are about half the size of a credit card, the pads are very small and the holes in them are about 0.6mm in diameter.

If it wasn't because you had gone through this in that other thread and the guy was nice enough to post pictures, it would've taken at least 80 replies from you for me to be able to digest this and finally see those three bridges.

Please tell me if I should do additional continuity tests to determine any damage to the PCB's, or if even though not perfect, these cuts are OK...

Thanks again, Andrew.
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