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Old 3rd December 2010, 12:37 AM   #1
kamaths is offline kamaths  United States
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Default Buffalo II module does not power up

Hello

I purchased a buffalo 2 dac in August and a placid supply in October 2010. I finally managed to assemble the placid supply and powered it up. I get 5.5v at the output of placid with 9 v ac in . The transformer I am using is avel which is capable of supplying 1.2 amp

When I connect the power supply to Buffalo, I do not see any leds lighting up on the Avcc module nor spdif lock. In fact the the voltage of placid drops to 1.6 Vwith buffalo dac board connected which is what I measure at DAC power input terminal as well as AVCC input . Thinking that it could be power supply issue, I used placid to power up 5v receiver section of my other TDA 1541 dac and it worked without any problem.

Am I missing something here .I was excited about this hearing this new dac. Please help
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Old 3rd December 2010, 10:36 AM   #2
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Have you tried adjusting the output current of the Placid?
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Old 3rd December 2010, 12:35 PM   #3
kamaths is offline kamaths  United States
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Yes. Reads per instruction manual exactly at 0.055V across R3.

Suresh
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Old 3rd December 2010, 12:39 PM   #4
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Quote:
Originally Posted by kamaths View Post
Yes. Reads per instruction manual exactly at 0.055V across R3.

Suresh
This is measured with the Placid connected to the load?
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Old 3rd December 2010, 10:42 PM   #5
kamaths is offline kamaths  United States
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Without load, placid output 5.45V with voltage across R8 measuring 0.35v dc and voltage across R3 0.055v

When buffalo is connected, placid output drops to 1.6v and R3 drops to 0 but voltage across R8 remains same at 0.35v Dc.

Adjusting VR1 does not bring up voltage across R3 to required specs of 0.05 and above.
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Old 4th December 2010, 12:20 PM   #6
avr300 is offline avr300  Denmark
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You must have a short.

Is the AVCC shunt board correctly orientated ?
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Old 4th December 2010, 12:25 PM   #7
kamaths is offline kamaths  United States
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Yes. I looked at the pictures of other boards posted in the forum and made sure the in, ground and out are correctly oriented on the AVCC module and the main board
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Old 4th December 2010, 12:29 PM   #8
avr300 is offline avr300  Denmark
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Grab a picture and attach it. Says more than 999 words.
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Old 4th December 2010, 01:41 PM   #9
jrenkin is offline jrenkin  United States
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Look for simple mistakes. The "short" idea os good. Check all your solder joints and make sure you have no bridges.
Also check other components, like the diodes, that are easily reversed. I found out I had put a diode in backwards on the placid and it worked, but not at the correct voltage/current until I fixed it.
Check both the placid and buffalo boards.
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Old 5th December 2010, 12:21 AM   #10
kamaths is offline kamaths  United States
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Double checked placid parts .All OK
Went over both boards with magnifying glass. Nothing wrong that I could see.
Attached are some pictures of the assembly
Attached Images
File Type: jpg buffalo with placid.jpg (924.5 KB, 157 views)
File Type: jpg undersurface of placid.jpg (275.7 KB, 156 views)
File Type: jpg acvcc module removed.jpg (657.0 KB, 145 views)

Last edited by Russ White; 5th December 2010 at 02:22 PM.
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