Salas hotrodded blue DCB1 build - Page 24 - diyAudio
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Old 5th September 2010, 08:32 AM   #231
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Hello Salas,

I received the TX that was spec'd at 21v AC, I attached to my meter and it is more like 23.6v AC. Are the resistor spec you recommended for the CRC still valid or the TX is way over the top. If I need to I will get another TX closer to the 15 to 18v.

Thanks
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Old 5th September 2010, 02:43 PM   #232
Salas is offline Salas  Greece
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Is that an unloaded reading?
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Old 5th September 2010, 08:07 PM   #233
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yes that is correct, no load
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Old 5th September 2010, 08:43 PM   #234
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Make those resistors 47R, and it should give less VAC under load also.
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Old 5th September 2010, 09:13 PM   #235
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thanks
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Old 6th September 2010, 12:55 PM   #236
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Quote:
Originally Posted by Marra View Post
To ground the circuit I need to connect from the centre connector on the p/s input to chassis earth through a cl60?
Is there a diagram of this layout somewhere?

Thanks,

Russellc
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Old 6th September 2010, 06:14 PM   #237
Marra is online now Marra  United Kingdom
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Russel just run a wire from the centre connector of the A/C connector on the pcb to chassis ground through a CL60 thermistor and then to the earth tab on the iec input socket. AS per the F5 earthing.
Regards Keith
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Old 7th September 2010, 06:31 PM   #238
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So...

My DCB1 Blue is complete. Photos to follow...I am making up a preamp, which has the following components:

Mezmerize switcher section (10vdc from DCB1 by cable)
DCB1 Blue Edition
Lightspeed attenuator

I will also be putting a remote controlled powered volume pot in there later, but if we consider the lightspeed and remote as just a 10R pot for now, in what order should I put the signal? pot after B1 or before?

Also, regarding earthing. I am wary of connecting ANY of the pre-amp signal earths to the chassis earth or power earth for fear of creating an earth loop.

In my mind it makes a lot of sense to instead put all signal earths in the pre-amp straight through to the power amp without them touching a thing. They will then naturally connect to chassis/power earth on the power amp. Is this the best way of doing things?

Many thanks as ever
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Old 7th September 2010, 06:35 PM   #239
Marra is online now Marra  United Kingdom
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I fired up my DCB1 this morning using a variac to keep the secondary voltage to 15 volts all the leds lit up and the relay clicked in after a few seconds. My p/supply voltages are +9.63 and - 9.6 volts with offset readings of -0.2 and -0.7mv. Do I need to play with the leds to get above 10v or am I good to go? Im still waiting on Selectronique to send my transformer before I can have a listen; hope there not to long.
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Old 7th September 2010, 06:46 PM   #240
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Hi, I built a few and I generally have 0.4V to 0.5V difference between the positive and negative supplies. Offset around 3 to 4 mV so consider yourself a lucky guy as you're good to go.

Even when I match the LEDs they will differ when used in the circuit as clearly can be seen as they burn brighter at the positive supply. The string of 5 LEDs is 9.01V and 9.6V in the positive supply. I used yellow and red LEDs but the differences stay the same.


Quote:
Originally Posted by Russellc View Post
Is there a diagram of this layout somewhere?

Thanks,

Russellc
Please see this link for some info on page 2 and 3:

http://passdiy.com/pdf/balzenpre.pdf

Dual PSU layout - how does this look?
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Last edited by jean-paul; 7th September 2010 at 07:03 PM.
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