ablaze 0 Report post Posted September 7, 2003 power supply works. just not the amp. how to test diode polarity? Share this post Link to post Share on other sites
ckng 0 Report post Posted September 7, 2003 power supply works. just not the amp. how to test diode polarity? Use a multimeter. Set to OHMS mode and connect the probes to the diode. It should conduct one way but not the other. Polarity wise, the end with the white band (in the case of a 1N4001) is the cathode (negative). Regards CK Share this post Link to post Share on other sites
ablaze 0 Report post Posted September 7, 2003 diode's like this right? eg. current flow -------> so diode ---+ve:diode:-ve--> correct? I've attached more pics Share this post Link to post Share on other sites
ablaze 0 Report post Posted September 7, 2003 closer Share this post Link to post Share on other sites
ckng 0 Report post Posted September 7, 2003 diode's like this right? eg. current flow -------> so diode ---+ve:diode:-ve--> correct? That's right. Regards CK Share this post Link to post Share on other sites
jtfoo 0 Report post Posted September 7, 2003 (edited) Most DMM should have a diode check mode that measured the forwarding voltage of your diode. The symbol on the DMM should be that of a diode symbol. Putting the DMM's black lead on the white band of the diode and the red lead on the other end, will will the forwarding voltage of the diode.. No display means your diode not working or your have mixed up the ends. You can check your LED with this method too.. Edited September 7, 2003 by jtfoo Share this post Link to post Share on other sites
ablaze 0 Report post Posted September 7, 2003 whats "forwarding voltage"? is that how much the diode allows? mine reads 0.52v does that sound right? Share this post Link to post Share on other sites
Firefox 0 Report post Posted September 7, 2003 Funny... My previous post didn't make it through. Must be some forum glitch. I've found your problem. You failed to populate pads Q3L & Q3R which are essential for the left & right channel opamps to receive power. !!! Share this post Link to post Share on other sites
ablaze 0 Report post Posted September 7, 2003 that shouldn't be it, cos I've got V+ and V- of the LR channels tied to the ground channels' V+ V-, according to morsel's instructions. (actually I wanted separate rails, then I realised I didn't have enough of the 5486s ) Share this post Link to post Share on other sites
jtfoo 0 Report post Posted September 7, 2003 (edited) whats "forwarding voltage"? is that how much the diode allows? mine reads 0.52v does that sound right? Yup, 0.5V should be the forwarding voltage of a typical 1N400X... Use the same method you can check the polarity of your LED. I also notice you haven't jumpered across the S2. Solder wire across if you don't intend to add C7 & R7 for the bass boost. Edited September 7, 2003 by jtfoo Share this post Link to post Share on other sites
Firefox 0 Report post Posted September 7, 2003 (edited) that shouldn't be it, cos I've got V+ and V- of the LR channels tied to the ground channels' V+ V-, according to morsel's instructions. (actually I wanted separate rails, then I realised I didn't have enough of the 5486s ) The 2N5486's sink out about 10mA of current or so.the 4 jfets there sink out 20mA to 40mA at best per rail. Your 3 opamps, rail-splitters & capacitors will need more current than that to operate properly. =) Edited September 7, 2003 by Firefox Share this post Link to post Share on other sites
Firefox 0 Report post Posted September 7, 2003 (edited) One more important factor. You haven't added TLE2426's for each of the left & right channels. It's a must! You must also place a 10pF cap across C6G & jumper across R3G! Edited September 7, 2003 by Firefox Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted September 7, 2003 (edited) Since you busted 2 TLE's, connect the ground of the TLE to left and right channel... Edited September 7, 2003 by jasonhanjk Share this post Link to post Share on other sites
ablaze 0 Report post Posted September 7, 2003 wah. so many replies suddenly jt: S2 IS jumpered. too small to see? hehe ben & jason: ben, I've been reading tangent's step-by-step guide over and over again. including checking with his pictures. C6G and R3G are not necessary. I didn't add the TLEs on the L and R cos I was checking with morsel and ppl and they said if I tie the ground's V+ V- to the L and R V+ and V-, I won't need the other 2 TLEs. ANYWAY, turns out..the DC jack was a lil screwy. I got light on the LED now! new problems, DC offset on L and R outputs are good <1mV. but on ground channel, it keeps rising and rising..hmm.. Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted September 7, 2003 HOw much is it rising? Share this post Link to post Share on other sites
