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Old 26th February 2009, 02:10 PM   #241
schro20 is offline schro20  United States
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Default Re: Re: Re: C9 & C21 Caps comparison

Quote:
Originally posted by ClaveFremen
C9 and its bypass(C21) are in the feedback loop so they're directly in the signal path.
Doh. Of course.

peter
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Old 26th February 2009, 02:19 PM   #242
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Default Re: Re: Re: C9 & C21 Caps comparison

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Originally posted by ClaveFremen

In the attached picture you could see how a 12,5mm cap fits.
You could always install C9 on the bottom of the board if it gets too big.
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Old 26th February 2009, 02:26 PM   #243
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Quote:
Originally posted by samsagaz
well, i will drop the boards to the trash, im really deseseperated, 4 Boards Build 1 works 3 NO

Btw, have any others in stock i will purchase another kit if have some in stock, i really dont want to still burning and broken components (removing it from the PCB), i will purchase more if have in stock and will try to get better luck next time.

Im really not good removing components i already ****** up 1 transistor, 1 Zener, 1 LM3886


Don't throw away the PCB's. They are still good even if the components are blown / burnt/ shot.

I promise to review the build today and look for issues.

At worst case you can ship the brds to me and I will reassemble them and ensure they are working before I ship back.
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Old 26th February 2009, 02:52 PM   #244
schro20 is offline schro20  United States
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Quote:
Originally posted by samsagaz
CHecking one of the PCBs i noticed 36 volts between C14 Pins its OK? in the schematic i see that i need to have 24 instead 36, or im wrong?
Dear Samsagaz,

I don't have my working board in front of me, otherwise we could compare (mine is in parts right now because I am building the case...)

You said you have one working board? I would recommend that you first compare this board with a non-working one. First do a visual compare of all the components. Then do test points like you seem to be doing and see what one board shows versus the other.

Just looking at the diagram you would expect to see less than 36 (obviously you expect about 24) when current is drawn. If no current is drawn there will be no voltage drop across R14.

What does your working board show?

Peter
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Old 26th February 2009, 03:08 PM   #245
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Default Re: Re: Re: Re: C9 & C21 Caps comparison

Quote:
Originally posted by marc brown
You could always install C9 on the bottom of the board if it gets too big.
Silmics are 25 mm tall, not so easy to mount on the bottom...

it's easier with C21, like I did for MKP1837.

Upgrading C21 to a MKS2 is cheap and a drop-in one, no space problems and has a big effect. (at least in my case)
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Old 26th February 2009, 03:45 PM   #246
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Quote:
Originally posted by schro20

Dear Samsagaz,

I don't have my working board in front of me, otherwise we could compare (mine is in parts right now because I am building the case...)

You said you have one working board? I would recommend that you first compare this board with a non-working one. First do a visual compare of all the components. Then do test points like you seem to be doing and see what one board shows versus the other.

Just looking at the diagram you would expect to see less than 36 (obviously you expect about 24) when current is drawn. If no current is drawn there will be no voltage drop across R14.

What does your working board show?

Peter

Well i already checked the boards and looks all OK. the one that works, start from 0V and start growing. When reach 24V the relay make contact!
the one that dont work start from 0V too but when reach the 24V dont make the Relay to Work!
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Old 26th February 2009, 03:54 PM   #247
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Quote:
Originally posted by samsagaz



Well i already checked the boards and looks all OK. the one that works, start from 0V and start growing. When reach 24V the relay make contact!
the one that dont work start from 0V too but when reach the 24V dont make the Relay to Work!

Back up a little.

1. Picture of your pwr supply please. Trafo and wiring to the 3 inputs on the PCB.

2. Can you check the direction of each of the diodes on the boards? Make sure the bands are facing the correct direction.

3. Do you have ~37 volts on the LM3886 pins, ~ 12 volts on the 318 pins and 24 volts at the relay?
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Old 26th February 2009, 04:27 PM   #248
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Quote:
Originally posted by troystg



Back up a little.

1. Picture of your pwr supply please. Trafo and wiring to the 3 inputs on the PCB.

2. Can you check the direction of each of the diodes on the boards? Make sure the bands are facing the correct direction.

3. Do you have ~37 volts on the LM3886 pins, ~ 12 volts on the 318 pins and 24 volts at the relay?

1 - Conections are OK, GND close to the BIG CAPS, AC1 and AC2 later

2 - Diodes checked everything OK.

3 - i have 70V between PIn 1 V+ and Pin 4 V- of LM3886 and in the LM318 after i turn on the amp, i get 20V that start droping.. after like 5 seconds i have 17v.
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Old 26th February 2009, 04:34 PM   #249
troystg is offline troystg  United States
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Quote:
Originally posted by samsagaz



1 - Conections are OK, GND close to the BIG CAPS, AC1 and AC2 later

2 - Diodes checked everything OK.

3 - i have 70V between PIn 1 V+ and Pin 4 V- of LM3886 and in the LM318 after i turn on the amp, i get 20V that start droping.. after like 5 seconds i have 17v.

1. picture please.

3. 318 should have +/- 12 volts if I am not mistaken. If I recall correctly it is regulated via a 12 volt Zenner.
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Old 26th February 2009, 04:37 PM   #250
schro20 is offline schro20  United States
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Quote:
Originally posted by troystg
3. 318 should have +/- 12 volts if I am not mistaken. If I recall correctly it is regulated via a 12 volt Zenner.
Correct. See http://www.diyaudio.com/forums/attac...amp=1234532041

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