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AVCC shunt module for ES9018 on BII is partly dead...
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pinnocchio  
#1 Posted : Friday, June 24, 2011 1:19:37 PM(UTC)
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Brian, Russ,

I'm running a Dual mono setup with Tridents and Legato 3.1. The AVCC Shunt Reg module for feeding the ES9018 on the left channel BII has partly died this morning. I'm feeding the BII with a 5.40V on LCDPS and a soft start so there is no inrush.

This has been working great for the past 3 months for this module. My right channel I had for about a year without issue... I was using it in stereo mode.

What can we do about this? I swapped the AVCC working module from one BII to the other and everything is fine.

D1 on AVCC does not light up, so the only thing that could really go wrong in there is QP1-QP4, D1 or the opamp which I doubt is defective. Do you use D1 and D2 as voltage reference in the circuit?

Since there is no schematics, it will be hard to diagnose. What voltage should I feed on IN/GND and what should be the output on OUT?

Can I buy a module directly from you? That would be appreciated...

If not, what are QP1 - QP4 mouser part number and D1 and the opamp?

I'll first wait for your answers on what to test.

Thanks
Do
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pinnocchio  
#2 Posted : Friday, June 24, 2011 6:36:10 PM(UTC)
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Anyone?
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Russ White  
#3 Posted : Friday, June 24, 2011 7:27:41 PM(UTC)
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Are you sure that VD voltage is not sagging under load?
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pinnocchio  
#4 Posted : Friday, June 24, 2011 7:39:34 PM(UTC)
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Actually, to make it easier, I name the BIIs as left and right.

Left BII AVCC = defective
Right BII AVCC = working

Took right AVCC (working) and connected to left and powered up. Everything is working fine

Took left AVCC (defective) and connected to right and powered up. Nothing is working

I also look at input voltage of both BII and voltage on both BIIs is 5.40V - 5.42V. Voltage is not sagging.

Would it be better I power them lower like 5.00V - 5.25V

Thanks
Do
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Russ White  
#5 Posted : Friday, June 24, 2011 8:09:24 PM(UTC)
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Can you measure the voltage at the cathode of D1 to VD?
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Russ White  
#6 Posted : Friday, June 24, 2011 8:12:01 PM(UTC)
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Also please measure the voltage across R6 and R8. And if possible the voltage to GND from each of the opamp pins.
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pinnocchio  
#7 Posted : Friday, June 24, 2011 9:17:44 PM(UTC)
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Hi Russ,

Here's the results:

D1 cathode to VD = 0V
D2 cathode to VD = 3.32V

R6 and R8 quickly measure +/- 4V then quickly drop to 0V...

Opamp
Pin1 = 5.35V
Pin2 = 493mV
Pin3 = 2.09V
Pin4 = 0V
Pin5 = 2.09V
Pin6 = 496mV
Pin7 = 5.35V
Pin8 = 5.36V

Hope this helps

Thanks
Do
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Russ White  
#8 Posted : Saturday, June 25, 2011 3:21:34 PM(UTC)
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To me it appears as if replacing D1 may well resolve your problem. I can't remember which exact part we use, but it is a standard intensity green 1206 LED.

The bad AVCC module is not drawing excessive current correct?
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pinnocchio  
#9 Posted : Saturday, June 25, 2011 6:26:44 PM(UTC)
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Do you have any mouser part you could suggest?

I wouldn't want to impact sound at all

Could you sell me an AVCC module?

Thanks
Do
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Russ White  
#10 Posted : Saturday, June 25, 2011 7:45:35 PM(UTC)
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859-LTST-C150GKT should work great.
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pinnocchio  
#11 Posted : Saturday, June 25, 2011 9:05:02 PM(UTC)
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Thanks!

Will order this and test!

Do
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pinnocchio  
#12 Posted : Sunday, June 26, 2011 7:19:23 PM(UTC)
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Hi Russ,

Once I change the led D1, I would like to test the AVCC module out of the BII to ensure I don't bust it.

How much voltage should I feed VD and what should AVCC voltage be?

Can I test both AVCCs independently on the module or I have to feed them both at the same time? I'm guessing they're both positive rails?

Thanks
Do
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Russ White  
#13 Posted : Sunday, June 26, 2011 7:32:36 PM(UTC)
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AVCC is fed by VD, so same voltage in. About 5V is fine.

Output should be ~3.45V
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pinnocchio  
#14 Posted : Monday, July 4, 2011 5:40:04 PM(UTC)
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Hi Russ,

I've replaced the led but nothing changed... The led I removed is still operational.

By feeding the VD to 4.75V (using 3x AA batt) I get an output of 3.415V on VDD and this on both sides... I have done a couple solder touch ups... Voltage is good, maybe current is not...

What is the next step please?

I don't mind paying for a new AVCC module, really I don't mind, even though I know it died by itself. I just want to listen to my muse! PLEASE ;-)


Thanks
Do
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pinnocchio  
#15 Posted : Monday, July 4, 2011 8:08:47 PM(UTC)
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Hi Russ, Brian,

I have an order I'm placing at Digikey. I'm putting it on hold in case there is another part to test.

I'm waiting for your answer

Thanks
Do
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ihear21khz  
#16 Posted : Monday, July 4, 2011 10:30:44 PM(UTC)
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A simple idea while you wait for Russ: Compare the voltage readings around each component (relative to 0V rail) on both the working and failed AVCC module. If a difference shows up somewhere, you probably have found the faulty component.

Cheers
DF

Edited by user Monday, July 4, 2011 10:35:52 PM(UTC)  | Reason: Not specified
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pinnocchio  
#17 Posted : Tuesday, July 5, 2011 6:52:35 PM(UTC)
pinnocchio

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Thanks DF. Unfortunately sometimes this will also point to the part right after the one that is defective. I really don't want to mess with the working module and then have both defective...

I'll wait for Russ or Brian to answer me.

I do appreciate your suggestion, I'm just too chicken right now... ;-)

Thanks
Do
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Russ White  
#18 Posted : Wednesday, July 6, 2011 3:57:52 PM(UTC)
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I think DF's suggestion is a good one. And should not cause any harm as long as you are careful.

I am sure we can get you a new AVCC module if yours is dead.
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pinnocchio  
#19 Posted : Wednesday, July 6, 2011 6:45:13 PM(UTC)
pinnocchio

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Russ,

Do I have to power both VD individually or one side powers both?

I've started to test but I'm really nervous since components are SMD and are packed really close to each other.

Thanks
Do
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toast  
#20 Posted : Wednesday, July 6, 2011 7:29:04 PM(UTC)
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Pinnocchio,
You have breadboards? You should use that to hold down the AVCC module, supply voltage to it and test it with small probe and steady hand, slowly does it. Good luck.
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