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Eddie  
#1 Posted : Friday, June 10, 2011 11:36:39 AM(UTC)
Eddie

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Location: Netherlands

Hi all,
I use a Buffalo V1.0 since december 2008 to my great pleasure, recently combined with a Squeezebox Touch. When I connected my self-made linear supply to the Touch a saw a spark and the electricity went down in my whole house. Due to a combination of two big mistakes and some bad luck I had a short circuit between the output of my linear supply and the mains voltage! d'oh!

This week I installed a new Touch, it is working fine, I checked it with a headphone. But when I switched on the Buffalo both LEDs lighted up instead of only the Lock LED and there was no signal coming out. When the accident with the Touch happened it was connected to the Buffalo only with an SPDIF cable, my Buffalo is fed from a battery.

Can anyone tell me what it means that both LEDs are burning? Can I do something to get the Automute off? Any suggestions on what I could measure in order to find out what is wrong? (If you want some additional information on how the Buffalo is connected in my setup, see: http://www.phys.tue.nl/E.../detailsDigitalAudio.htm)

Kind regards,
Eddie
Russ White  
#2 Posted : Friday, June 10, 2011 12:50:14 PM(UTC)
Russ White

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My first suspicion would be that the comparator is dead. You may be able to only replace that. I would check the components around the comparator as well. If fixing the comparator and its components does not resolve the problem the DAC chip itself may be damaged.
Eddie  
#3 Posted : Saturday, June 11, 2011 7:22:28 AM(UTC)
Eddie

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Location: Netherlands

Hello Russ,

Thanks for the quick answer.

I just measured a few voltages:
VD = 6.06 volt
VA = 6.62 volt
VDD = 3.30 volt (measured at R14 near the SPDIF switch)
pin 3 of IC2 = 1.65 volt (measured at R14 other side, this is 0.5*VDD as to be expected?)
pin 1 of IC2 = 2.14 volt (measured at the SPDIF switch)

This output voltage seems strange to me. The SPDIF input was connected to the Touch that was switched off.

Unfortunately I will not be able to replace IC2. That is far beyond my soldering capabilities. So, what could be the next step?

Kind regards,
Eddie
Eddie  
#4 Posted : Monday, June 13, 2011 2:58:53 AM(UTC)
Eddie

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Location: Netherlands

Hello Russ,

I also checked the outputs of the DAC. With power off I measured the resistance:
left: + to G 369 Ohm and - to G infinite
right: + to G 345 Ohm and - to G 345 Ohm

with power on I measured these voltages:
left: + to G 0.213 Volt and - to G 0.000 Volt
right: + to G 0.001 Volt and - to G 0.000 Volt

So the left output channel is also suspected of damage. Anything else I could check?

I am about to take everything apart because my TA2021B amp also appears to be damaged.


Kind regards,
Eddie
Russ White  
#5 Posted : Monday, June 13, 2011 5:21:40 AM(UTC)
Russ White

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It is never a good idea to measure resistance with power on.

I am sorry to say that my best guess is your DAC is probably in a state where it will not be cost effective to repair it. I also don't happen to have a B1 in a state where I can confirm your measurements. Perhaps someone else of the forum does.
Eddie  
#6 Posted : Tuesday, June 14, 2011 3:00:03 PM(UTC)
Eddie

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Posts: 21
Location: Netherlands

Russ White wrote:
It is never a good idea to measure resistance with power on.

My previous message:
With power off I measured the resistance: ....
With power on I measured these voltages: ....

Russ White wrote:

I am sorry to say that my best guess is your DAC is probably in a state where it will not be cost effective to repair it. I also don't happen to have a B1 in a state where I can confirm your measurements. Perhaps someone else of the forum does.

Well, I do make mistakes occasionally, and this one with the power supply was by far my biggest in just over 40 years of DIY audio.

If anyone who reads this message has a leftover B1 in a good state, please let me know.


Kind regards,
Eddie
NicMac  
#7 Posted : Wednesday, June 15, 2011 3:45:13 PM(UTC)
NicMac

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Location: Italy

I do if you are referring to the one with ESS9008. I also got some IVY and Counterpoint output stages for it.
Let me know if you are interested.
Nic
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