Buffalo II module does not power up

kamaths · 3rd December 2010, 12:37 AM

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

Russ White · 3rd December 2010, 10:36 AM

Have you tried adjusting the output current of the Placid?

kamaths · 3rd December 2010, 12:35 PM

Yes. Reads per instruction manual exactly at 0.055V across R3.

Suresh

Russ White · 3rd December 2010, 12:39 PM

Quote:

Originally Posted by kamaths

Yes. Reads per instruction manual exactly at 0.055V across R3.

Suresh

This is measured with the Placid connected to the load?

kamaths · 3rd December 2010, 10:42 PM

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.

avr300 · 4th December 2010, 12:20 PM

You must have a short.

Is the AVCC shunt board correctly orientated ?

kamaths · 4th December 2010, 12:25 PM

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

avr300 · 4th December 2010, 12:29 PM

Grab a picture and attach it. Says more than 999 words.

jrenkin · 4th December 2010, 01:41 PM

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.

kamaths · 02:22 PM

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

3rd December 2010, 12:37 AM	#1
kamaths diyAudio Member Join Date: Nov 2007	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

3rd December 2010, 10:36 AM	#2
Russ White diyAudio Member Join Date: Jan 2005 Location: Nashville, TN, USA	Have you tried adjusting the output current of the Placid? __________________ Less pulp more juice Twisted Pear Audio.

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3rd December 2010, 12:35 PM	#3
kamaths diyAudio Member Join Date: Nov 2007	Yes. Reads per instruction manual exactly at 0.055V across R3. Suresh

3rd December 2010, 10:42 PM	#5
kamaths diyAudio Member Join Date: Nov 2007	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.

4th December 2010, 12:20 PM	#6
avr300 diyAudio Member Join Date: Sep 2005 Location: DK	You must have a short. Is the AVCC shunt board correctly orientated ?

4th December 2010, 12:25 PM	#7
kamaths diyAudio Member Join Date: Nov 2007	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

4th December 2010, 12:29 PM	#8
avr300 diyAudio Member Join Date: Sep 2005 Location: DK	Grab a picture and attach it. Says more than 999 words.

4th December 2010, 01:41 PM	#9
jrenkin diyAudio Member Join Date: Nov 2007 Location: Denver, Colorado	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.