squalle 0 Report post Posted April 26, 2006 btw, the 10pF cap is the same. just different brand and when I checked yours out, it's actually made by vishay, while mine just some cheap ones LOL I dont think you need to change the 10pF just that, becareful not to accidentally swap the caps around. there's no labelling on the caps is there? good luck again ~enjoying voice of susan wong + pint + um2~ Share this post Link to post Share on other sites
heady 0 Report post Posted April 26, 2006 Changing computer, finally can log in again. Thanks for the tips. Share this post Link to post Share on other sites
heady 0 Report post Posted May 1, 2006 squalle - second built has exactly the same problem as the first. I am still using the ferrites I bought as the type you used are not here yet from Farnell. So will put this aside and wait for the ferrites to come. Hope that's the reason for the oscillation. Share this post Link to post Share on other sites
squalle 0 Report post Posted May 2, 2006 so have u got the ferrites today? Share this post Link to post Share on other sites
heady 0 Report post Posted May 3, 2006 Replace the ferrite today and it still has the same high power consumption. This is one tough amp to build. Putting it away for time being, no time. I ordered two more boards from Tangent, you wanna build one for me? Thanks. Share this post Link to post Share on other sites
heady 0 Report post Posted May 8, 2006 I tried to resurrect the previous PINT board. I restored the connections for the trace which I cut and also for those traces which lifted off when I desoldered the parts to trouble-shoot. I then soldered the components as per Tangent's list, execpt for the gain resistors which I set for gain of 3. For the opamp, I used TS922ID which is the only alternative opamp I could find in SG. The result -> awful sound. Sounds like the ground connection is bad. I have checked all the soldering with the DMM and they looked ok. Checked the voltage the V+ and V- is ok but the VG seems to be wrong, not the middle of V+/V-. Any suggestions re: the virtual ground? The resistors are reading correctly in the DMM. Share this post Link to post Share on other sites
squalle 0 Report post Posted May 8, 2006 errm, how far off is it from the mid-value? ground op-amp input is correctly at mid-value (or thereabout)? if so, it means your ground op-amp is somehow oscillating or, the feedback's broken? anyway, if you meet me, please bring it and I'll take a quick look and see if I have any idea to help you out at most leave it with me for some tests Share this post Link to post Share on other sites
heady 0 Report post Posted May 8, 2006 (edited) errm, how far off is it from the mid-value? ground op-amp input is correctly at mid-value (or thereabout)? if so, it means your ground op-amp is somehow oscillating or, the feedback's broken? anyway, if you meet me, please bring it and I'll take a quick look and see if I have any idea to help you out at most leave it with me for some tests Was testing with 9V battery and got slightly more than 6V from one (forgot whether + or -) to VG. Forgot to measure the other direction. When my new boards arrive, you can have all my failures plus the new board. If you don't mind, that is. Thanks -EDIT- Oh yeah, the current draw was a ridiculous 2mA. Edited May 8, 2006 by heady Share this post Link to post Share on other sites
heady 0 Report post Posted May 8, 2006 Using 4AA batteries (abt 6V), + to VG was 5V and - to VG was about 1V. Measuring the resistors, I get 46.7K for both +/- to VG and 93.4K for + to -, so no short anywhere. Share this post Link to post Share on other sites
squalle 0 Report post Posted May 8, 2006 then I think ur ground opamp is clipped to the max output might be due to oscillation? or can be due to broken feedback Share this post Link to post Share on other sites
heady 0 Report post Posted May 20, 2006 I am happy to report that my second PINT built with AD8397 is now working ok. I could not test it for the last couple of weeks due to work and also because my new DMM cannot now measure DC current. I bought a new analog multimeter and used it instead. Also, instead of using 3 AA cells like squalle, I used a 9V battery. The current draw is now in the mid-fifties mA which is what it should be. Thanks squalle for all your help and support. You are a great pal. BTW - my first built which I also tried a substitute opamp (TS922) sounds really odd even with the 9V supply. I officially pronounced it dead. Share this post Link to post Share on other sites
squalle 0 Report post Posted May 20, 2006 explain the oddities? ermmm arent u supposed to pass one to me to troubleshoot? Share this post Link to post Share on other sites
heady 0 Report post Posted May 20, 2006 squalle, I was supposed to pass you both the PCBs I built and another new one for you to built. While waiting for the parts, I was testing the PCBs but turn out my DMM became unable to read the current draw. No idea why, it works for resistance and voltage but now won't conduct current. Anyway, bought a new multimeter and using a 9V battery, I could see the current draw is about 50mA. The first PCB using the TS922 has a really weird sound. I can't explain it but it sounds like a very coloured sound, with a squashed sound stage, highs missing. Maybe some phase problem? Once in a while can hear some distortion. The PCB has been very badly treated by me, soldering,desoldering and resoldering, I am not surprised it isn't working properly. I think I don't need to ask you to built the new PCB after all. But if you like, I can send you the one with the TS922, just for fun. I am quite hard up for time lately. So much work, so little time for diy.... Share this post Link to post Share on other sites
kross 0 Report post Posted May 21, 2006 my current draw was about 45mA. used a cheapo casing found in SLS which looks quite well..all in all quite satisfied with the SQ and the ease of building. very compact too..thanks squalle... Share this post Link to post Share on other sites
heady 0 Report post Posted May 22, 2006 Hi kross, how about some pics of your PINT in its casing? Share this post Link to post Share on other sites