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Mini3 No Sound Left Channel

post #1 of 8
2/9/10 at 9:33pm
Thread Starter 
I just finished the second Mini3, doing the extended version with schottky diodes. When I installed the battery a couple things happened, one the battery got warm (didn't notice till later) and I had crosstalk & intermittent sound out of the left channel until I turned the volume more than half way then it would kick in. Now there is no sound on the left at all. I checked all the joints and looked for solder bridges but everything looks good.
Could I have fried the volume control while soldering? I did let the pads heat a few seconds before soldering the connection.
Anyone else run across this same scenario, if so I'd appreciate some direction.
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post #2 of 8
2/9/10 at 9:43pm
Quote:
Originally Posted by ovrclkd View Post
I just finished the second Mini3, doing the extended version with schottky diodes. When I installed the battery a couple things happened, one the battery got warm (didn't notice till later) and I had crosstalk & intermittent sound out of the left channel until I turned the volume more than half way then it would kick in. Now there is no sound on the left at all. I checked all the joints and looked for solder bridges but everything looks good.
Could I have fried the volume control while soldering? I did let the pads heat a few seconds before soldering the connection.
Anyone else run across this same scenario, if so I'd appreciate some direction.
While it's possible to 'fry' a volume control while soldering it, it requires GOBS of heat and rather than frying the pot, what happes is that the plastic case melts and the terminals could detach.

Have you checked the orientation of the electrolytic capacitors?

cheers!
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post #3 of 8
2/9/10 at 9:53pm
Is D4 in backwards? Also, did you go through every step in the "initial check" section of the Mini³ website? Which step does it fail? (i.e., quiescent current, DC offset, etc.)
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post #4 of 8
2/9/10 at 11:26pm
Thread Starter 
I have sound out of the left channel again from 1/3 volume up, but it's doesn't reach it's "full" volume.

Here's what I have in ohms:

◦Battery + and - contacts: 225
◦U4 pins 7 and 4: 15
◦U4 pin 7 and IG: 11 to 14
◦U4 pin 4 and IG: 16 to 20
◦U5 pins 8 and 4: 5
◦U5 pin 8 and IG: 330
◦U5 pin 4 and IG: 12
◦Output jack tip (OL) to sleeve (OG) : 12
◦Output jack ring (OR) to sleeve (OG) : 3.9
◦Output jack tip (OL) to IG : 1.8
◦Output jack ring (OR) to IG : 1.8
◦Output jack sleeve (OG) to IG: no reading

Thanks in advance for the help ....
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post #5 of 8
2/10/10 at 2:49am
Quote:
Originally Posted by ovrclkd View Post
Here's what I have in ohms:

◦Battery + and - contacts: 225
Were these measured with the battery in place? If so you should remove the battery and re-test. If not, is "225" really in ohms, Kilo-ohms or Mega-ohms?

Quote:
◦U4 pins 7 and 4: 15
◦U4 pin 7 and IG: 11 to 14
◦U4 pin 4 and IG: 16 to 20
◦U5 pins 8 and 4: 5
◦U5 pin 8 and IG: 330
◦U5 pin 4 and IG: 12
Ditto the above. If it really is these low tens of ohms then you have a serious short. Also something doesn't make sense, you have 11-14 ohms at U5 pacross pin 7 and IG, but 330 ohms at U4 across pin 8 and IG? These two locations measure the same thing... same for U5 pin4-IG and U4 pin4-IG and U5 pin7-pin4 and U4 pin8-pin4, they also measure the same thing yet your readings are inconsistent.

Quote:
◦Output jack tip (OL) to sleeve (OG) : 12
◦Output jack ring (OR) to sleeve (OG) : 3.9
ohms, K ohms, M ohms? These are also seriously shorted if they are in ohms.

Quote:
◦Output jack tip (OL) to IG : 1.8
◦Output jack ring (OR) to IG : 1.8
◦Output jack sleeve (OG) to IG: no reading
If these are in K ohms then it's about right.

A note to everyone: when reporting measurement results, please specify the reading's proper unit and multiplier!
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post #6 of 8
2/10/10 at 1:45pm
Thread Starter 
Quote:
Originally Posted by amb View Post
Were these measured with the battery in place? If so you should remove the battery and re-test. If not, is "225" really in ohms, Kilo-ohms or Mega-ohms?


Ditto the above. If it really is these low tens of ohms then you have a serious short. Also something doesn't make sense, you have 11-14 ohms at U5 pacross pin 7 and IG, but 330 ohms at U4 across pin 8 and IG? These two locations measure the same thing... same for U5 pin4-IG and U4 pin4-IG and U5 pin7-pin4 and U4 pin8-pin4, they also measure the same thing yet your readings are inconsistent.


ohms, K ohms, M ohms? These are also seriously shorted if they are in ohms.


If these are in K ohms then it's about right.

A note to everyone: when reporting measurement results, please specify the reading's proper unit and multiplier!
OK, let me begin by asking you to forgive my lack of electronic skills but I am here to learn as well as build.
I had the volume down on my ZEN player before so I put it up to MAX.
Now the volume is VERY loud at the lowest setting coming out of the right side, as I turn the volume up the left side begins to come in finally equalizing at just over half way. (which by then using my test SENN 202's is about blowing my eardrums out and I play guitar thru mesa 4 x 12 cabs )

I set the meter to Cen-Tech meter to 2000 and here are readings:
NR = No Reading

◦Battery + and - contacts: NR
◦U4 pins 7 and 4: NR
◦U4 pin 7 and IG: NR
◦U4 pin 4 and IG: NR
◦U5 pins 8 and 4: NR
◦U5 pin 8 and IG: 342
◦U5 pin 4 and IG: NR
◦Output jack tip (OL) to sleeve (OG) : NR
◦Output jack ring (OR) to sleeve (OG) : NR
◦Output jack tip (OL) to IG : 1830
◦Output jack ring (OR) to IG : 1827
◦Output jack sleeve (OG) to IG: NR

quiescent current draw 10.9

Rail Splitter check V= to V- 9.3v / v- to IG 4.6v

Output DC offset check: meter at 200mv
IG to OG: 0.4mv
IG to OL: 0.1mv
IG to OR: NR

Battery Charging Circuit Check: OK
16.5 mv Bat + & -
12.7 volts at Bat + & -

Thank you for any insight you may have as to what the issue is.
I've check and rechecked for solder bridges and obvious shorts and the battery temp is ok.
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post #7 of 8
2/10/10 at 2:06pm
I had a similar problem at one time with my mini3. Started out intermittent, then became more permanent.

I suggest you measure the volume control. I had a dry joint on the ground pin on one channel. It looked OK on visual inspection.

I eventually fixed it by desoldering the entire control, cleaning all the pins, coating them with flux and then resoldering it. No problems in the 2 years since. The offending ground pin looked quite dirty when I took the control out.

It also happened to a couple of other people on the old HeadWize threads. I think there is an occasional manufacturing problem

Kevin
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post #8 of 8
2/10/10 at 3:34pm
Thread Starter 

Thank You!

Quote:
Originally Posted by knorthover View Post
I had a similar problem at one time with my mini3. Started out intermittent, then became more permanent.

I suggest you measure the volume control. I had a dry joint on the ground pin on one channel. It looked OK on visual inspection.

I eventually fixed it by desoldering the entire control, cleaning all the pins, coating them with flux and then resoldering it. No problems in the 2 years since. The offending ground pin looked quite dirty when I took the control out.

It also happened to a couple of other people on the old HeadWize threads. I think there is an occasional manufacturing problem

Kevin
!!!BINGO!!!

THANKS KEVIN!

And Thanks to Ti & the other "emergency responders"!
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