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adn6244

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Posts posted by adn6244

  2. Posted · Edited by adn6244 · Report reply

    went to koba after lunch...searched for 30 minutes..they don't have the 100kx2 pot that has 8 pins like the Alps. Those that they have are either 6 pins or the size is too big or only 100k pot with 6 pins and no built in switch. I'll try Well later.

     

    Thanks for the suggestion so far.

     

    Another alternate solution is to increase the resistor value...is this worth trying? Do I change R15/16 pr R11/12?

     

    If the voltage is 4.5v to either channel (?), is this the max voltage that will flow thru?

     

    Pardon my layman words I don't have the elec eng background to quote it in the smarter manner and still desperately trying to find something that may work. :party:

  4. Posted · Edited by adn6244 · Report reply

    Hello,

    I need help...what's new :bash:

     

    I bought the amp from Dr Meier Meier Audio but the problem is now finding the Alps 100k pot!! I tried many places except koba, the pot is really difficult to get.

     

    While I have spare 10k pot from the old projects, I don't know how to increase the resistor value to compensate for the decrease in pot's resistance. :no:

     

    I read this ohm's law but which resistor to change

     

    The diagram is attached or can be found in the above link...all help is greatly appreciated! :cans::party:

    [attachmentid=4008]

    Corda.bmp

  6. Posted · Report reply

    Bro...I was trying to desolder the battery connector to file down the parts but wasn't successful so i reflow the solder on the battery connector. But now my mini3 suddenly has high quiescent current reading > 150mA, does anyone knows which part is causing the problem? :helpsmilie:

     

    The amp sounds fine using the power adaptor mode though. :rclxub:

  7. Posted · Report reply

    go to the seller shop (jaben or stereo) and test it out yourself using your own player and earphone...or you can try theirs but have to warn you...you may spend more than $200 at the end :grin:

     

    Personally I started diy small amps recently and music using amp sounds "nicer" and "louder" to me but it depends whether you can hear the difference or not.

  8. Posted · Edited by adn6244 · Report reply

    Ok...finally I finished my Mini3 on Tuesday nite with lots of detemination and discipline on how many components I solder each day to avoid complaints from my home minister.

    :bash:

     

    ok :b2t ... the AD8397 was actually working fine from the beginning. uglyjoe pointed pin 7 to the wrong resistor. Discovered it after checking the diagram. :doh:

     

    Last nite, spend a few hours testing the amp following amb's method and duh...things went wrong again!!!!

     

    First it passes all the test and i was full of expecation and relief...but when i plug in the earphone...how come it sounds like my first jaben cmoy but no matter where i touch it just won't sound sweet!!! :rclxub:

     

    The led that i temporary "cucuk" in the hole also didn't light up and I am so afraid of shorting the amp i didn't try listening it with the wall charger on.

     

    I thought it's another write off...until i decided to try it with the power adapter on... :cans: suddenly...i got the music back...it's all because of the low battery power !!!

     

    The 9v I bought from SLT has less than 5v after using it on the jaben cmoy for less than 2 hours!!

     

    Now can't wait to box it :holiday::thumbup:

  9. Posted · Report reply

    wah, you really getting into one project after another huh? Actually, same goes for me, next up after mini3 is SOHA than Millett hybrid. hee hee :D

     

    Hehehe...the Mini3 is giving me enough problem already...flow and reflow solder still pin 7 giving me high resistance reading. This CKKIII is a longer term project but I need to get something else from Farnell so may want to order first.

     

    Here's what I ordered from Farnell. Please check if complete as I may have some parts already. Rename the extension to .csv and open it in Excel or OpenOffice.

     

    Thanks heady. I will check the list.

     

  11. Posted · Report reply

    koba also carries the sanwa MM. I bought the analog YX360 not too long ago. the uncle showed me both digital and analog but i bought the analog one...took me some time to get use to the different meter reading ... digital is much easier for lazy ppl like me

     

     

    What uglyjoe method? Can post the link?

    That's normal and means each pin is soldered to pad. But doesn't guarantee that the opamp will be ok especially the AD8397. This opamp is very sensitive to shorts elsewhere. Make sure the pcb is clean before apply power which will happen when you solder the battery tabs. And be very careful afterwards to drain the caps immediately before touching the amp.

     

     

    Uglyjoe method link found in post 18 above. ;)

     

    I just started the opamp soldering and now i dare not continue. so there is no way i can tell whether AD8397 is faulty or not.... :sweat: luckily i ordered another 8397 as spare...i knew it won't be that easy for me :wacko:

     

  12. Posted · Report reply

    actually follow uglyjoe method all zero resistance except for pin 7. didn't adj the meter when i first checked the reading.

     

    from opamp pin to pad all return zero. is this normal? shall i continue to finish the rest cause removing the opamp after putting in all the components going to be difficult.

  14. Posted · Report reply

    Hello...it's me again :bash: problem problem....

     

    I soldered the opamp on the pcb and tried testing it using the method posted by uglyjoe HERE

     

    All reading is around 2ohm except for U5 pin 7 where one probe at R4R returned 200ohm :cry:

     

    Is this considered short or fried or just cold joint? :rclxub::helpsmilie:

     

     

  15. Posted · Report reply

    Hello,

     

    I refer to the EIA table and found that for E96 +/- 1% tolerance resistor, the value is 24.3k ohms but in farnell I can only find 24k...is it ok to use 24k to replace 24.3k? Any particular rules that I need to follow or as long as the parts tolerance range is overlapping should be fine?

     

    Other than farnell, locally where can i find WIMA caps that is +/- 5%? I found +/-10% but not sure can be used to replace the +/-5%. does it mean the output will not be so "precise" or detailed if I use higher %?

     

    :helpsmilie:

    :grin:

     

     

    thanks.

  17. Posted · Report reply

    Oooh...I din really check his ebay price but I tried upload his BOM to mouser...parts alone cost approx USD28++ excl shipping. Some of the parts cannot be found at Farnell or I haven't tried hard enough :bash:

     

    I tried to look for other portable amp project but I think so far Mini3 is the only best options available but it looks so much more complicated than the cmoy though!! :lust::shocking:

     

    I didn't know the jaben cmoy can be upgraded ...he he he .. I'm still learning!!

     

     

     

     

     

  21. Posted · Report reply

    I spend some time troubleshoot desolder and test and test until one fine day...... :rclxub: I wanted to force out the Dip socket and resolder...and pull out 2-3 small rings on the pcb :prettyprincess:

     

    Went jaben and bought another set and spend few hours to prepare and finally soldered the working cmoy :cans::dance:

     

    Now will move on to the m3 :thumbup: soon ...very soon ..

  24. Posted · Report reply

    opamp 833...not sure if this is the problem.

     

    I thought this opamp should have been changed by jaben but I was given this opamp when I bought the unit approx 2 weeks ago.

     

    I don't have other opamp to test so not sure it is giving the problem.

     

    I tested the voltage, it's less than 20mV so it didn't blow my cheap earphone. Although this test is not conclusive of whether the opamp is working or not!!

  25. Posted · Report reply

    has to touch both pins in yellow box to get the "right" output :no:

     

    will try to desolder-resolder the input/output jack tomorrow.. the battery wire broke when i was trobleshooting and just managed to rewire it after spending few hours to remove the residual....

     

    will try to post photo later...

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