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uBitX - problem with power draw and failed chip

Michael Aiello
 

Hello,

I just received my uBitX and started wiring it up per the instructions. I wired up the power connector with the diode installed, and measured the draw from the main board, and it was high: 140 ma. Then there was a loud crack - it appears the TDA2822 chip cracked.
After the chip failed, the board is drawing a steady 82ma.

I have found a local source for the TDA2822M and have ordered a few parts. I will replace the chip, but here is my question: 
what else should I be checking on the board?
Is there a list of test points and volages to check? I'm just concerned that the chip failure was caused by some other issue on the board.

The only other out of the ordinary thing I noticed was that the bolts holding the heat sinks on the finals were loose. I tightened them before starting the assembly.

Thanks for any help or suggestions

73, Mike N2HTT

 

Mike,

That may happen if power supply voltage was too high.

The chip may have been soldered wrongly - please check.

2822 is a very tough chip, I have melted a breadboard but the chip survived.

Raj

At 13-02-2018, you wrote:
Hello,

I just received my uBitX and started wiring it up per the instructions. I wired up the power connector with the diode installed, and measured the draw from the main board, and it was high: 140 ma. Then there was a loud crack - it appears the TDA2822 chip cracked.
After the chip failed, the board is drawing a steady 82ma.

I have found a local source for the TDA2822M and have ordered a few parts. I will replace the chip, but here is my question:Â
what else should I be checking on the board?
Is there a list of test points and volages to check? I'm just concerned that the chip failure was caused by some other issue on the board.

The only other out of the ordinary thing I noticed was that the bolts holding the heat sinks on the finals were loose. I tightened them before starting the assembly.

Thanks for any help or suggestions

73, Mike N2HTT

Michael Aiello
 

My supply voltage was 13.8, is that too high? That is nominal 12v supply.

I will check the chip 
orientation before replacing the 

Thanks 
Mike




On Feb 13, 2018 8:07 AM, "Raj vu2zap" <rajendrakumargg@...> wrote:
Mike,

That may happen if power supply voltage was too high.

The chip may have been soldered wrongly - please check.

2822 is a very tough chip, I have melted a breadboard but the chip survived.

Raj


At 13-02-2018, you wrote:
>Hello,
>
>I just received my uBitX and started wiring it up per the instructions. I wired up the power connector with the diode installed, and measured the draw from the main board, and it was high: 140 ma. Then there was a loud crack - it appears the TDA2822 chip cracked.
>After the chip failed, the board is drawing a steady 82ma.
>
>I have found a local source for the TDA2822M and have ordered a few parts. I will replace the chip, but here is my question:Â
>what else should I be checking on the board?
>Is there a list of test points and volages to check? I'm just concerned that the chip failure was caused by some other issue on the board.
>
>The only other out of the ordinary thing I noticed was that the bolts holding the heat sinks on the finals were loose. I tightened them before starting the assembly.
>
>Thanks for any help or suggestions
>
>73, Mike N2HTT





 

Mike,

The voltage is fine, something else blew it. Chip cracking mean catastrophic failure..

Check for solder bridge short etc.. these boards are checked before they are sent out.

Raj

At 13-02-2018, you wrote:
My supply voltage was 13.8, is that too high? That is nominal 12v supply.

I will check the chipÂ
orientation before replacing theÂ

Thanks
Mike

Michael Aiello
 

Okay thanks Raj. It will bed a few days before I get the new chips, I'll review the board  
73 Mike N2HTT 

On Feb 13, 2018 9:31 AM, "Raj vu2zap" <rajendrakumargg@...> wrote:
Mike,

The voltage is fine, something else blew it. Chip cracking mean catastrophic failure..

Check for solder bridge short etc.. these boards are checked before they are sent out.

Raj

At 13-02-2018, you wrote:
>My supply voltage was 13.8, is that too high? That is nominal 12v supply.
>
>I will check the chipĀ
>orientation before replacing theĀ
>
>Thanks
>Mike




 

Mike,

Now break the 2822 and remove the pins one by one. Put in a socket.
If everything looks alright then you can get audio from the volume control top lead
and listen on an ampli speaker.

Raj


At 13-02-2018, you wrote:
Okay thanks Raj. It will bed a few days before I get the new chips, I'll review the board Â
73 Mike N2HTTÂ

On Feb 13, 2018 9:31 AM, "Raj vu2zap" < rajendrakumargg@...> wrote:
Mike,

The voltage is fine, something else blew it. Chip cracking mean catastrophic failure..

Check for solder bridge short etc.. these boards are checked before they are sent out.

Raj

At 13-02-2018, you wrote:
>My supply voltage was 13.8, is that too high? That is nominal 12v supply.
>
>I will check the chipĀ
>orientation before replacing theĀ
>
>Thanks
>Mike

Michael Aiello
 

Okay I will do that, and continue with wiring up while I'm waiting for the new 
chip 
Thanks  
Mike N2HTT 

On Feb 13, 2018 10:01 AM, "Raj vu2zap" <rajendrakumargg@...> wrote:
Mike,

Now break the 2822 and remove the pins one by one. Put in a socket.
If everything looks alright then you can get audio from the volume control top lead
and listen on an ampli speaker.

Raj

At 13-02-2018, you wrote:
Okay thanks Raj. It will bed a few days before I get the new chips, I'll review the boardĀ Ā
73 Mike N2HTTĀ

On Feb 13, 2018 9:31 AM, "Raj vu2zap" < rajendrakumargg@...> wrote:
Mike,

The voltage is fine, something else blew it. Chip cracking mean catastrophic failure..

Check for solder bridge short etc.. these boards are checked before they are sent out.

Raj

At 13-02-2018, you wrote:
>My supply voltage was 13.8, is that too high? That is nominal 12v supply.
>
>I will check the chipĀ
>orientation before replacing theĀ
>
>Thanks
>Mike

 

Hey Mike,

I know why it didn't work, it doesn't glow in the dark:-) No seriously folks, that's a bummer. The TDA2822M's speaker output is not referenced to ground and must be isolated from ground. It's a BTL amp. I toasted one first time I used it because I didn't know this. Just a thought.

Joel
N6ALT

 

Disregard that last comment Mike, I was confusing the TDA2822 with the TDA7052A, oops.

Joel
N6ALT

Michael Aiello
 

Hey Joel,  thanks for the head's up. I'll look for any possible ground path. The board was sitting on a piece of wood on the bench, it's not likely I shorted a pin, but I'll be more careful. 


On Feb 13, 2018 12:41 PM, "Joel Caulkins" <caulktel@...> wrote:
Hey Mike,

I know why it didn't work, it doesn't glow in the dark:-) No seriously folks, that's a bummer. The TDA2822M's speaker output is not referenced to ground and must be isolated from ground. It's a BTL amp. I toasted one first time I used it because I didn't know this. Just a thought.

Joel
N6ALT

Michael Aiello
 

Hi Raj,
I received the replacement TDA2822 today, so I removed the bad chip, replacing it with a socket. Socketing a new 2822, I fired up the board and am pleased to report the board is now drawing just a hair under 90ma, and nothing has exploded. I think I am back on track.
I won't be able to finish the wire-up until next week, because I am traveling for the next few days, but I think the rest will go according to plan.
Thanks for the help
73
Mike N2HTT