A GC Layout check.

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S.C

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Joined 2003
YA, it feel good. The sound as you guys said is tight and realistic. It didn't have too much colored sound.:bigeyes: I can turning it up to really loud .:cool: 24V rail will be an idle powersupply. 20-25V Supply is the way to go.:bigeyes: :devilr:

Thx a lot you guys, you guys have been helpping me a lot since I started this board. A guy call Jon wanted to produce some board out of this circuit, and good luck to him too. People enjoy. :)
 
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S.C

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Joined 2003
A few more questions,

1. Do I connect all the ground to the Case any where? Even the ground from the PCB"the input ground" and the "To Case ground"? However, since the input RCA screwed on the case and ground, should I still connect "the input ground" from the PCB to the RCA pot or just the case? And should I attach the female power pot that ground to case?

2. I ordered a 330VA 25/25V TorXXX transformer with 4 wires secondart, how can I connect it to two bridge? and how to make 2 0V out of dual secondary?

P.S Man my transformer will be devilevr by Aug 13, and I'm gonna back to Hong Kong by 14.........T_T
:bawling:
 
Nuuk

Nuuk

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Joined 2003
decdun.me.uk
Hi Solomon,

I would keep your phono sockets isolated from the metal case. Then connect the power ground star on the PCB to the case via a resistor and cap in parallel ( see the DDFAQ page).

To wire up your transformer for two rectifier bridges, connect each pair of secondary wires to the ~ connections on the bridges and then connect the -DC point of one bridge to the +DC point on the other bridge. The mid point of that connection is the 0V which should then be connected to the power ground star on the amp circuit.
 
S

S.C

Member
Joined 2003
Nuuk said:
Hi Solomon,

I would keep your phono sockets isolated from the metal case. Then connect the power ground star on the PCB to the case via a resistor and cap in parallel ( see the DDFAQ page).

To wire up your transformer for two rectifier bridges, connect each pair of secondary wires to the ~ connections on the bridges and then connect the -DC point of one bridge to the +DC point on the other bridge. The mid point of that connection is the 0V which should then be connected to the power ground star on the amp circuit.
Click to expand...

Nuuk thx for the reply,
but nuuk, didn't I already have a cap and a resistor parallel on my PCB? See http://hk.geocities.com/solomon_choi/GC2.html the "MG" pot and the "TC" pot on the right hand corner.
(MG=Main Gound=0V, TC=To Case) so just connect the case to "TC" pot, right? and "MG" to the 0V

After I isolated the phone sockets from the case and connect the ground to the "IG" right? (IG=Input Ground)

As you say I connect a wire from one +V DC bridge to another -V DC, but I have only one +/- left am I connecting it parallel to two Amp section? or what?

P.S: Do you have any tips for isolating the case from the phone sockets? That's why you guys using Al case.:bawling:
 
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GrahamnDodder

Member
Joined 2003
Nuuk-

I have been learning from SC's thread, even tho I am going P2P wiring with my GC.

I have a little bit of confusion with the ground, too.

Power Gnd goes to case via a cap and resistor. Values? Wattage/voltage rating? I would hope there is not too much current/voltage assumed to be across this connection...

Also Power Gnd goes to Sig Gnd, straight connection.

But the thing I am most confused about is that if power gnd, which is a DC Virtual Ground, goes to the case via a cap and resistor, and the earth ground, which is a "true" ground, also goes to the case, is that going to cause me problems?

Or does the fact that one is an A/C earth and the other is a DC virtual, and they are separated by a transformer, make it okay?

Assuming his thingie works, I should have lots of good quality pix of the process when I am done.

Thanks,

GnD
 
Nuuk

Nuuk

Member
Joined 2003
decdun.me.uk
Solomon. - sorry I forgot that we made provision for the resistor/cap on your PCB. In that case you only need to connect it to the case.

You can buy insulated phono sockets or make a panel from a non-conducting material to mount the sockets on.

This is the circuit diagram for using two rectifier bridges that used to be on the chip amp forum.

An externally hosted image should be here but it was not working when we last tested it.


I think that it should work OK for two channels but perhaps somebody else can confirm that.

Graham, the values for the resistor and cap are given on the FAQ page at Decibel Dungeon.
 
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GrahamnDodder

Member
Joined 2003
Nuuk-

Thanks.

I see that your diagram does not include the earth ground on the AC. Are you not using a 3-way plug? Are the different (2-prong only) over there?

But my main concern is still the idea of connecting both the AC earth and the DC virtual ground to the same chassis? Is that somehow okay becuse of the transformer isolating the two?

Thanks,

GnD
 
Nuuk

Nuuk

Member
Joined 2003
decdun.me.uk
But my main concern is still the idea of connecting both the AC earth and the DC virtual ground to the same chassis? Is that somehow okay becuse of the transformer isolating the two?
Click to expand...

The case is connected to earth and the powerground star (0V) is connected to the case via the resistor/cap. If you connect directly, the case may act like an antenae.

We do have three pin plugs in the UK. I connect the earth wire to the power supply casing and then run a wire from there to the casing of the amplifier.
 
S

S.C

Member
Joined 2003
GrahamnDodder said:
Nuuk-
But my main concern is still the idea of connecting both the AC earth and the DC virtual ground to the same chassis? Is that somehow okay becuse of the transformer isolating the two?
Click to expand...

I think your guess is right, cuz most of the Torxxx transformer grounding on the screw on the core. So you screw/blot on the case and following this
An externally hosted image should be here but it was not working when we last tested it.
it grounded. Also if you using an AL case will not matter at all cuz it don't conduct electricity.:devily:

I think you come from Headfi/ headwize right?:devilr:
 
C

carlosfm

Banned
Joined 2003
S.C said:
Opps, I thought my muti meter didn't bee...beee equal to no connection. Sorry, man have a nice sleep. It is 3:01 PM here. :bigeyes:
Click to expand...

If your multimeter doen't bee...beee, it means that it's not conducting.
With a little luck, what you have there is anodized aluminium, and, more luck still, you made a hole, mounted the chip with thermal paste and a screw and it may not be touching anywhere that's not anodized (like the internals of the hole you made).
I have L-shaped aluminium bars, anodized, that simply don't conduct, only on the extremes where they were cut.
 
S

S.C

Member
Joined 2003
Problems appear:

My transformer, I connect it like you said and I got +/-38V. The fuse won't even blow at 3A fast blow. and I coonect two lights on it it lights up.


However, I started to connect two lights , one light neg ->neg and pos->0V, the second just oppsite. an parallel connect both amp section parallel to the +/-38V, and the 0V join together and connect it to the 0V. Now the fuse start to blow, even I dis connected the amp section. (even 3A slow blow)

I notice something when I close the light and start the amp, one of the bridge freshed and the fuse blow together in a sec after I turned on th amp. One time a light keeping light on thatt flashing side of the bridge, while the fuse already blowed. It keeps on for like 15sec.

Should I try the higher value, or sommething wrong with the bridge?
 
S

S.C

Member
Joined 2003
Oh god I think I burned the MUR860............ I checked the flashed side diodes only K have conduction with the screw hole, but A is gone. However, why there is light on that side when I blow my fuse everytime. The side of the bridge 2 out of 4 only K appear conduction with the screw hole, but not A. The 2 remained are able to make conduction from the screw hole to K and A

P.S Or my guess oppisite will be right?:bawling: :bawling:
 
Nuuk

Nuuk

Member
Joined 2003
decdun.me.uk
Oh god I think I burned the MUR860............ I checked the flashed side diodes only K have conduction with the screw hole, but A is gone. However, why there is light on that side when I blow my fuse everytime. The side of the bridge 2 out of 4 only K appear conduction with the screw hole, but not A. The 2 remained are able to make conduction from the screw hole to K and A
Click to expand...

Solomon, I can see nothing on your site!

And I can't understand what you are saying about the rectifier bridges. Have you mounted the diodes on a heatsink? If so have you insulated them?

What is this 'conduction from screw hole' all about?
 
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