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jasonhanjk

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Posts posted by jasonhanjk

  1. Posted · Report reply

    Jason, I received my boards today!!! Thank you. I finished building my first board. I hit a few snags with using electrolytic caps with a too small uF rating. I used 220uF 25v elna cerafine caps which caused a huge amount of DC offset. And caused the chips to be starved for power. They were running hot and oscillating badly. I removed the 220s and installed some 470uF caps and now everthing is ok. 1.3mV DC in the right channel and 0.7 in the left. The amp is drawing about 50 mA of current.

     

    Sorry I missed your post. The amp shouldn't draw 50mA current. I don't see the 2 10k resistor, those are for stabilizing the virtual voltage.

     

     

     

    But after which I found a lot of distortion to the right channel not like static but like noise (varying in amplitude) but this does not increase over how I change the volume and is present even when the volume is set to zero. Any idea what can be wrong and how do I trouble shoot.

     

    Have you clean the PCB? ;)

  2. Posted · Report reply

    Hmmm. From Blake's result, the problem lies with the OR pin, the OPA2134B opamp.

    Is that opamp socketed? Change a new socket may help, I had previously encounter a bad contact socket. What you can do is using a cutter and cut the socket to 8 pieces. That should make removing it easier.

     

    The LM6171 should be ok. ;) The min +-5V is required for the opamp to meet the manufacturer spec.

  3. Posted · Report reply

    Hi, sorry for coming in late.

    Can you do a few quick measurements on the pin so I can help to diagnose? The cap in the spec seems ok. Also check for correct connections for your input and output stereo jack. Make sure it's not solder wrongly.

     

    In DC mode with referrence to V-:

    OL

    OR

    OG

    +pin of C7

    +pin of C6

     

    And finally the voltage across C4.

     

    IPB Image

  6. Posted · Report reply

    The courier is really really espensive. I tried once and it cost around $50 sing... :no: 2-3 days delivery.

    Registered cost less than $10 (depends on weight) and will take 10 working days. If the other party doesn't receive, bring your receipt to singpost and submit a complaint.

     

    There are some parcels or envolope (with bubbles in it) available at Singpost. :))

  8. Posted · Report reply

    5% is ok.

     

    It should be called high pass filter. ;)

    If following the spec straight, should gives around -3dB at 18Hz.

     

    Ok, kianannsim.

    Make sure the pot is at min.

    Take the multimeter and measure the DC for left and right channel with respect to ground. What do you get?

    Also can post the picture of your board, front and back?

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