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Mini^3 Issues

post #1 of 17
5/9/11 at 10:41am
Thread Starter 

So today I finally got all the parts on the board. But when going through the initial check on the AMB page I am arriving at some issues.

 

Quiescent current check:

The mA reading was around 30mA (high performance ) is that too high?

 

I have problems in the following steps:

Output DC offset check- when testing the OL vs the IG I get a negative big number (too low for the 200mV setting)

And for OG vs IG I get -0.5mV

 

Also for the last step (checking the charging circuit) I get infinity when I test the battery contacts (when it should be reading 16mA) And the wallwart adapter is okay, it reads about 18V.

 

 

I am a n00b with DIY so any help would be appreciated!

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post #2 of 17
5/9/11 at 4:43pm

With a combination of high DC offset and higher then expected idle current, looks like you need a new U5 but it may be a good idea to try re-flowing the solder joints before replacing it.

Did the charge indicator (LED1) illuminate when you connected the AC adapter to the amplifier?

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post #3 of 17
5/9/11 at 9:40pm
Thread Starter 
Quote:
Originally Posted by MisterX View Post

With a combination of high DC offset and higher then expected idle current, looks like you need a new U5 but it may be a good idea to try re-flowing the solder joints before replacing it.

Did the charge indicator (LED1) illuminate when you connected the AC adapter to the amplifier?


Okay, I tried reflowing the 5,6,7 pins because the schematic says those are the ones that associate with the left. I will reflow the whole chip though.

 

And no it did not... :( Dang I really messed this one up haha.

 

Edit: I just reflowed the U5 chip (all pins) and tested with the IG and all came out to be unmeasurable ohms so I assume that is okay. So maybe it is something else, I will look closely at the joints again (I reflowed all of the left's components already earlier today). So idk. Also not to mention how can the right circuit pass the initial check but not the left if the chip is dead? Don't both left and right circuits utilize the U5?

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post #4 of 17
5/13/11 at 8:34am
Thread Starter 

Bump

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post #5 of 17
5/13/11 at 6:06pm

When I blew my U5 I got the same thing (in my case I forgot to clip the elongated leads off the battery contacts when filing them down and they shorted off the bottom of the case and that was enough to kill U5). I got high quiescent current (chip gets REALLY hot fast) and one channel was dead (the one with the high offset) but the other was working (test with a pair of headphones you don't mind destroying if you must).

 

Both channels go through U5, but usually only one gets shorted. Still have to replace the whole chip though.


Edited by Teal - 5/13/11 at 6:09pm
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post #6 of 17
5/14/11 at 9:07am
Thread Starter 
Quote:
Originally Posted by Teal View Post

When I blew my U5 I got the same thing (in my case I forgot to clip the elongated leads off the battery contacts when filing them down and they shorted off the bottom of the case and that was enough to kill U5). I got high quiescent current (chip gets REALLY hot fast) and one channel was dead (the one with the high offset) but the other was working (test with a pair of headphones you don't mind destroying if you must).

 

Both channels go through U5, but usually only one gets shorted. Still have to replace the whole chip though.


That is precisely what happened to me! I forgot to mention that part. The case I got has a slight concave in on one side so it touched the leads. But okay I will replace the U5 and go from there.

 

I thought it was the capacitors cause thats what actually touched the case, but I replaced those and nothing happened.

 

But I still need to look into the charging circuit.

 

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post #7 of 17
5/14/11 at 9:51am

If u guys are using the 1455c801 case, what batteries are u guys using? mine have more width and that makes them in compatible.

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post #8 of 17
5/14/11 at 10:44am

I spent quite some time reading datasheets and checking battery sizes in my quest for a specimen that would fit. I now use a 250mAh battery. I also have new a 200mAh one that fits too. I bought both of them @ Conard.com

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post #9 of 17
5/14/11 at 12:20pm

And what make is it?

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post #10 of 17
5/14/11 at 6:02pm

I used the battery that came with the GlassJarAudio kit. It was too thick to fit in the case (thickness as in the dimension of the shortest side), so I cut off the label and sanded down the plastic from both sides. All 9v I've come across have the same size, but vary in how much extra plastic they have around it.


Edited by Teal - 5/14/11 at 6:04pm
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post #11 of 17
5/15/11 at 1:13am
Quote:
Originally Posted by psgarcha92 View Post

And what make is it?



Their own brand. Just something they get made by a (most likely) German manufacturer.

http://www.conrad.com/NiMH-rech.battery-9-V-PP3-250-MAH.htm?websale7=conrad-int&pi=250024&ci=SHOP_AREA_14717_0501035

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post #12 of 17
5/16/11 at 9:47am
Quote:
Originally Posted by Teal View Post

I used the battery that came with the GlassJarAudio kit. It was too thick to fit in the case (thickness as in the dimension of the shortest side), so I cut off the label and sanded down the plastic from both sides. All 9v I've come across have the same size, but vary in how much extra plastic they have around it.


I had to do the exact same thing, as did my buddy when he built his mini3.  Trimming up the leads on the underside of the board BEFORE inserting into the case is a must also, as I believe has been mentioned.

 

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post #13 of 17
5/16/11 at 11:43pm
Thread Starter 

Is it possible that my U1 or U2 chip might be blown? I say this because the LED (charging) doesn't light up and I test infinity on the battery contacts, for the "checking the charging circuit"  where it should read 16mA. I have not replaced the U5 yet. But reading the schematics this doesn't have anything to do with the charging circuit. (Please correct me if I'm wrong)

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post #14 of 17
5/17/11 at 12:01am

Do you have C2 installed the right way around?

(the marking on the case is the positive lead on tantalum capacitors)

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post #15 of 17
5/17/11 at 1:54pm
Thread Starter 
Quote:
Originally Posted by MisterX View Post

Do you have C2 installed the right way around?

(the marking on the case is the positive lead on tantalum capacitors)



Yes it is. The positive lead is in the positive hole

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