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Old 16th June 2008, 08:30 AM   #111
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Default here is the Mooly amp circuit

Hi mooly,

This Vro-board for test purpose.

I have just semi finished mooly amp. It is pro type circuit havenít check yet. Just finished parts lying. There are C5 and C8 still not yet fix due polarity confused. Any way now I know it is actually 10uf. And R8 we can use from 470. Later on I will finish this part.

Here is the circuit on vro aboard.

Later on I need test measurements info from mooly.

Best regards.
michael

Click the image to open in full size.
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Old 16th June 2008, 08:52 AM   #112
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mooly, i think i need to mske sure for mosfets connection. here can't read properly too small font.
---------------------------------
2sk1058 on the -v rail
G = goes to R21
D= goes to -v rail
S= goes to R24
-----------------------------------
2sj162 on the + rail
G = goes to R18
D= goes to +v rail
S= goes to R23
--------------------------
is this correct connection?
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Old 16th June 2008, 11:35 AM   #113
Mooly is offline Mooly  United Kingdom
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Hi Space,
That was quick First things first. Before you switch on disconnect ALL 6 wires that go to the FET's. You can power it all up without these connected, make sure nothing is connected to the input and output lines.

Connections to the FET's. The 2SJ162 is the "top" one that goes to the positive rail. The SOURCE goes to the +45 volt rail and the DRAIN is the output that goes to the 0.22 ohm. The 2SK1058 is the "bottom" one and again DRAIN is the output and SOURCE to - 45 volts. The 270 ohms that go to the gates, these MUST be placed on the pins of the FET's VERY IMPORTANT. Also don't have all those wires twisted together keep them separate and short.

With the FET's NOT CONNECTED, power it up and check that the output is at ZERO volts DC. Check that there is 12 volts across pins 4 and 7 of the IC and that there is about 0.7 volts across R5 the 100 ohm. I can't see a preset (R8) in your picture. You MUST use a pot to begin with. If you have no pot then for now short it out, that is link collector Q5 and collector Q3. DONT use a fixed 470 ohm.
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File Type: jpg 2sk1058.jpg (50.2 KB, 1354 views)
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Old 16th June 2008, 11:48 AM   #114
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I am sure you know this but better mention it, the clean ground has to go to the PSU ground. The junction of C10 and C11 also go to this point
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Old 16th June 2008, 02:05 PM   #115
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hi mooly,

update.

without connect mosfet there is 0 voltage on output but when i attach mosfets there showing high voltage like 16v. its some where got bugs definetly (human error).

i am not using high voltage for now. i am using only 24vdc for testing perpose. should i use only 12v for testing? still need to find where is the bugs......have to check the circuit was properly build. let you know tomorrow. i checked TL071 4-7pin have 12v.
i also plcd R8 pot and adjusted 470ohms.

thank you.
michael
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Old 16th June 2008, 05:28 PM   #116
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Hi Space,
Sounds like you are nearly there. I will be away most of tomorrow from about 8.30AM, so here are a few things to check.
First make sure the pot is set to zero ohms, not 470. It must read dead short from collector Q3 to collector Q5.
You need at least -/+ 20 volts or so even for testing, but with the outputs disconnected nothing will go pop.

1. Run it up without the FET's connected-- all 6 wires disconnected.

2. Confirm pin 7 of IC is connected to ground.
Confirm pin 4 is at -12 volts --- if you are using a low supply voltage you may need to drop R27 the 10 K feeding the zener to around 5K6 but only do this if the 12 Volts is low.

3. Confirm the output is at Zero volts to within a few millivolts.

4. Confirm that there is 0.6 to 0.7 volts across R5. This will show the current source Q2 and Q3 are working correctly.

5. If that is OK read on DC volts across R17. If you now adjust the pot the voltage across R17 will vary going from zero to perhaps 6 or 7 volts or so. The voltage across R22 should vary in the same way but the two readings will not be equal until the outputs are connected.

If all that is OK then all that remains is to connect the outputs but first set the pot back to ZERO again so there is no voltage across R17 and R22.
Refer to the picture I posted for the pin outs. The 2SJ162 is the top one connected to the positive rail. The 270 ohm gate resistors must go on the FET itself, not on the PCB. The source which is the middle leg goes to the positive rail. The drain goes to the 0.22 ohm.
Do the same for the 2SK1058. Again the middle leg goes to the negative rail and the drain to the other 0.22 ohm.
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Old 16th June 2008, 06:25 PM   #117
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Space--- Look at post 77 of Alex's PCB. This may make it easier to visualise how to connect the FET's . Look how near the 270 ohm gate resistors are to the FET. Nice job that Alex by the way
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Old 18th June 2008, 06:01 AM   #118
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Default update making amp

hi mooly,

Today i have tried again. i think i am very near to getting proper volage at output. it's now showing 5.67v on output, there is some were can be error. so i need to check even more details. voltage at +rail are very good, showing 0v. only have problem on -rail which is showing 0.200v, as i know it should be 0v. its responding the input only problem is high voltage at output. i will let you know update.

thank you for your help.

best regards
michael
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Old 18th June 2008, 06:32 AM   #119
Mooly is offline Mooly  United Kingdom
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Hello Michael,
Did you get my message outlining various tests to make
Follow the instructions
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Old 18th June 2008, 07:44 AM   #120
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Default update again

hi mooly,

finally i can hear the sound of your amp. great sound.

ok, there are still a bit problem when i make the pot to 0v then R17 showing 0vlt too but R22 showing 200mv. when i connect the input there are no more showing this voltage on R22 and output gets under 0v too...anyway now it is working fine on my 24vdc.

sound quality can't tell right now as it is on low voltage.

trble is nice but the vocal is a bit rough not so sweet as it should be. very musical.

i think you are now online...

thank you.
micahel
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