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Old 25th December 2012, 02:49 PM   #1
50AE is offline 50AE  Bulgaria
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Default DAC burnt, I am getting sick of it.

Merry Christmas!

Not glad it happened at Christmas exactly, so I'll try to enjoy and forget about it. I am disappointed because there won't be high end audio for the hollyday. But I am curious to find out the reason why it happened.

My setup is: Te7022L cheap board from eBay with a 12MHz oscillator, to AKM4396 with I2S connection.

Few days ago I decided to remove the SLA battery and Salas shunt regulators and try the DAC straight on NiCd -> 5V for the analog and digital part of AKM4396 and 3,2V (made by 3 diodes in series for the voltage drop for the Te7022L). The 5V of the same pack for the oscillator.

In total 3 packs of Ni-Cd. One for the analog part, one for the digital part of AKM4396 and one for the Te7022L board.

I plugged it on and I was very happy with the sound! Been listening for hours and hours and hours. Better sonics than with the SLA and Salas regs.

Yesterday I've been listening to music the whole day. I decided to let the system play at night, while I was sleeping.

So I woke up at 08AM to hear oscillation from my tubes, like if there was no signal. I saw on the computer screen a message that my USB device is no longer recognized.

I thought that my batteries were discharged, though I wonder how it would be possible, because the DAC draws no more than 50mA and each pack is 1000mAh(2x1000mAh), 5000mAh for the analog part. Digital draws about 10mA and analog 40mA.

So I charged them a bit. Then I plugged the DAC again and the same message appeared - Problem recognizing USB. Then I touched the diodes going to the Te7022L chip, they were hot. WTF I thought, then I touched the Te7022L chip and it was hot like hell!

I really don't know what happened. The diode voltage drop is OK. The Te7022L chip is fed at its nominal voltage.
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Old 25th December 2012, 04:51 PM   #2
DUG is offline DUG  Canada
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Exact NiCd voltage?

What diodes?

What was the DAC supply V before it blew up?

Is the OSC still running? P/N or max V for OSC?

Any chance of a schematic?
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Old 25th December 2012, 05:17 PM   #3
Mooly is online now Mooly  United Kingdom
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Could the sequencing of supplies be critical ? Some appearing or disappearing before other and a causing a latch up ?
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Old 25th December 2012, 06:21 PM   #4
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Default Smoked TE7022?

I wonder if running the digital on the AK4396 at 5 was a problem for the TE7022? And was the 5 really 5? Not much of a load...did you measure the NiCADs right off the charger? And were you applying the V you THOUGHT, to the TE7022? Did you have say 100ohms in series with each I2s leg to the DAC?. Were these separate modules? Were they fer sure kept at same ground-potential? Did you ALWAYS run the oscillator at 5V Before? And how is that signal coupled to the TE7022? a Cap, a R? DIRECT? [ I would use a 3.3V oscillator? Or maybe 2 R's...a voltage divider for the clock pulses?] And the TE7022L internal 1.8V pins, you didn't slip up and make a bridge from one of them to the 3.3 did you? pins 9, 19, 24, and 40 have TE7022 1.8V if you bridged any of those... or to any pins that don't want +3.3...
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Old 25th December 2012, 06:44 PM   #5
50AE is offline 50AE  Bulgaria
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Quote:
Originally Posted by DUG View Post
Exact NiCd voltage?

What diodes?

What was the DAC supply V before it blew up?

Is the OSC still running? P/N or max V for OSC?

Any chance of a schematic?
1. Diodes are HER602

2. The DAC supply was unknown, but sure lower V before blowing up, because it ran for almost a day. 4,95V for the analog, 5,05V for the digital AKM4396 stage, and 4,98 and 3,4V for the digital part of TE7022L

3. I have no idea, I don't have a scope to verify.

4. I don't have a schematic, but I used this: TE7022L USB Module Card Assembled Board for DAC5 by Weiliang | eBay

The boards are connected via star ground

Quote:
Originally Posted by enjoybiking View Post
I wonder if running the digital on the AK4396 at 5 was a problem for the TE7022? And was the 5 really 5? Not much of a load...did you measure the NiCADs right off the charger? And were you applying the V you THOUGHT, to the TE7022? Did you have say 100ohms in series with each I2s leg to the DAC?. Were these separate modules? Were they fer sure kept at same ground-potential? Did you ALWAYS run the oscillator at 5V Before? And how is that signal coupled to the TE7022? a Cap, a R? DIRECT? [ I would use a 3.3V oscillator? Or maybe 2 R's...a voltage divider for the clock pulses?] And the TE7022L internal 1.8V pins, you didn't slip up and make a bridge from one of them to the 3.3 did you? pins 9, 19, 24, and 40 have TE7022 1.8V if you bridged any of those... or to any pins that don't want +3.3...
1. I have no idea.
2. It was really 5 in the first run, when I got the NiCds off the shop
3. After charging the NiCds were 5,4V.
4. Yes, I have 100 ohms with each I2S leg to the DAC
5. Yes, separate modules
6. Yes, same ground potential.
7. Yes, the oscillator had a 5V series regulator which I removed.
8. OSC signal is coupled via a 100R to the TE7022L.
9. Haven't bridged or touched anything to the 1,8V pins


In the worst case, 0,3 volts over the Te7022L and 5,4V on the OSC, not sure if these could have been immediately fatal. But I imagine the DAC has stopped working in the previous morning.

What I don't like at all is the lack a DETAILED DATASHEET about TE%@!@#$!@L ! How can I get an idea at least about the MAX SPECS?

Last edited by 50AE; 25th December 2012 at 06:52 PM.
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Old 25th December 2012, 08:00 PM   #6
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http://www.yoyodyneconsulting.ca/dow...AC-release.pdf

http://www.gfec.com.tw/documents/101...2SL_PB-v21.pdf

do YOU have a schematic of the TE7022 board from Min? And did Oscillator have a step-down to 3.3? Or it takes +5 from one of the 10 gold pins at card's edge? I KNOW you need 4 pins for I2s, 3-4 for the RAW USB and +/- PWr [on USB cable], ground...

DO you have separate AGND and DGND?

I am trying to find a TE7022 schematic SHOWING a TTL oscillator not a crystal, no luck YET, maybe I'll find it yet.
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Old 25th December 2012, 09:08 PM   #7
50AE is offline 50AE  Bulgaria
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The oscillator used to take 5V directly from a series reg on the board. I removed the reg and applied 5V directly from NiCd.

There are two grounds that are connected to a star ground near the battery negative. One ground is from the Te7022L board, the other is the AKM4396 board ground.
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Old 26th December 2012, 01:58 AM   #8
DUG is offline DUG  Canada
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"3. After charging the NiCds were 5,4V."

http://www.asahi-kasei.co.jp/akm/en/...k4396_f00e.pdf

Says max 5.25V...some digital goes to 5.5V...not this one
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Old 26th December 2012, 04:18 AM   #9
qusp is offline qusp  Australia
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yep, overvoltage seems the problem, NiCd is without a doubt considerably noisier and higher impedance than your Salas reg and SLA. NiCd has a noise floor of around -80dB -> -90dB, a good 50dB (100000x) higher (at least) than the salas reg. using batteries directly is only going to equal or better shunt regs if you use quieter chemistries like LiFePO4 and NiMH isnt bad either, but their main advantage is isolation.

without any type of protection or current limiting, it will have just fried itself at the first sign of trouble. i'm surprised you didnt have DC on the output terminals to the amp->speakers.


so my advise is to just try and get it working how it was before.
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Old 26th December 2012, 08:08 AM   #10
50AE is offline 50AE  Bulgaria
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DUG, check the datasheet carefully. On MAX operating conditions, it is indicated 6.0 volts. 5,25 volts is the max recommended value.

Check this out (for battery noise) http://tf.nist.gov/timefreq/general/pdf/1133.pdf

Tomorrow I'm going to replace the I2S board with PCM2706 and see if the AKM4396 is intact.

Last edited by 50AE; 26th December 2012 at 08:24 AM.
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