That'll do it. Its just enough to send the partially off chipamp.com kit, totally berserk. How that happens, usually, is that it wasn't designed for stereo builds (but rather monobloc). To fix it, you'd just have to hookup anything ground related to that big green "X" in the middle of the drawing. Once met, never again. And the ground(s) all met once there, so that has established the only valid hookup point.This may help identifying the ground loops.
Wiring such as one ground wire to the potentiometer, one ground wire to the speaker jacks, one ground wire to the rca jacks, could be important for stereo builds.
yeah starting a personal attack, that's not considered gentlemanly where I come from.. sheesh.
I have no idea what your talking about voting for winners and losers...I reckon yer just hurt from me laughing about your free offer to chipamp.com.
Last edited:
The very real problem is that the chipamp.com kit was designed as a starter/incomplete kit for a monobloc build; which, causes needless complications if someone wanted a stereo build with it.
Regardless of how it may look on first glance, we should never expect a real engineer to react disproportionately. If they're the real deal, the severity of the comments is always proportionate to errors in the circuit. Even though you might have to take a moment, such negative comments are usually valuable for information purposes.
Also, don't hesitate to ask them to do something more specific, because indeed that works brilliantly!
Silence is the worst answer from an engineer. Compare: A cussout means that he does care and thinks that you should have and are able to do better. It is kind of an offbeat compliment, in a way.
Also, those guys are rarely specific, because they think that you should have already done that.
Anyway, so long as they're talking, they've intended to be helpful--try and figure out what they really said.
I already had a fight with that thing, and I lost. Years later, Philfr succeeded. It was only after that, I'd found out that it was possible to make a good practical amplifier from that kit. The surprise was excellent!
the OP is silent as well, some vocal ppl has proclaimed the "problem" is due to oscillations from a bad PCB layout. I don't see any evidence of that here in this thread, or from the many other builds.
I reckon the OP is having multiple errors hooking the thing up and reading instruments E.g basic learning curve for beginners. He never did post an image of the bench test up! as for vocal thread individuals, I've come to think that some have sort of beliefs system that might worked for their builds, that they in turn have apply to every situation. Do I try to convince the all the vocal religious folks to come down off their soap boxes ... that would be foolish too.
BTW controlling stray line currents from introducing a third wire is another matter.
I completely forgot about that.
However the photo around here, about pulling out 4 diodes and adding some jumpers, to convert the chipamp.com power board for center tap, is my photo. It has 3 conductors in, and 3 conductors out.
So, indeed I had used a center tap.
It was in a circa 1976? rig, which had a 2 prong power cord.
I don't see a path between the load and source ground. Is there one?
Hi everyone:
Thanks for checking back with me. Yes, I openly admit to not knowing what I'm doing. However, I did finally manage to get that friend of mine to help me scope the power supply boards today.
I've got some screenshots and some CSV files to post, which I'll do in the next day or two. It's late here.
For both PSU boards, the plot looked awful. Both sides of each power supply output something resembling a a sawtooth wave, and the voltages were way too high as well.
Thanks again for your persistence in helping me. Will post screenshots as soon as I can.
Thanks for checking back with me. Yes, I openly admit to not knowing what I'm doing. However, I did finally manage to get that friend of mine to help me scope the power supply boards today.
I've got some screenshots and some CSV files to post, which I'll do in the next day or two. It's late here.
For both PSU boards, the plot looked awful. Both sides of each power supply output something resembling a a sawtooth wave, and the voltages were way too high as well.
Thanks again for your persistence in helping me. Will post screenshots as soon as I can.
Does it work? did you build it to the guidelines ? post symptoms or advice on what to test next. Once again, images of the test set up would be most helpful to folks trying to help!
if you're new to measurements things like PS rail O-scope shots may indeed look awful to the uninitiated, but the chip amp uses feedback and PSRR to clean it up at the output with in reason. IMO posting o-scope shots of the chip amp rails without any other data would be the worst troll thing a newb could post. I reckon half the folks here that have built one would be shocked as well! BTW It will never look good post O-scope shots of the output 1st sheesh
if you're new to measurements things like PS rail O-scope shots may indeed look awful to the uninitiated, but the chip amp uses feedback and PSRR to clean it up at the output with in reason. IMO posting o-scope shots of the chip amp rails without any other data would be the worst troll thing a newb could post. I reckon half the folks here that have built one would be shocked as well! BTW It will never look good post O-scope shots of the output 1st sheesh
Last edited:
with no load(rest of the circuit) voltages will measure higher and without specifying the scope's voltage scale, power supply ripple can seem horrible.(like looking at a fly's eye with a microscope)
it might seem like nit picking but understanding all conditions/setup for the test is important.
it might seem like nit picking but understanding all conditions/setup for the test is important.
Well, I've been told by my friend that we probably shouldn't post the scope shots until we do some more scoping. He will try to come over tonight or tomorrow.
I'm guessing that one reason for this is that on one PSU board, we initially had a very clean signal on one side, and that sawtooth-y looking signal on the other. We kept the volts/div scale very low for the side that looked clean. Later, when we reconnected the same board, both sides showed as sawtooth-y, but we didn't change the volts/div setting to make it equal for both sides. Not sure if that matters or not, as my friend is the only one with any knowledge of these things.
Perhaps I should have grounded the heatsink when the amp boards were connected. Thank you for that. However, this latest set of test results were only from PSU boards-no amp boards connected, so I don't think the heatsink grounding is relevant for this scoping. I will keep it in mind if we ever get past this stage.
I'm guessing that one reason for this is that on one PSU board, we initially had a very clean signal on one side, and that sawtooth-y looking signal on the other. We kept the volts/div scale very low for the side that looked clean. Later, when we reconnected the same board, both sides showed as sawtooth-y, but we didn't change the volts/div setting to make it equal for both sides. Not sure if that matters or not, as my friend is the only one with any knowledge of these things.
Perhaps I should have grounded the heatsink when the amp boards were connected. Thank you for that. However, this latest set of test results were only from PSU boards-no amp boards connected, so I don't think the heatsink grounding is relevant for this scoping. I will keep it in mind if we ever get past this stage.
if signal/ripple wasn't there the first time but it showed on the second try you may still have intermittent/bad solder joints....
hey quick question when you mounted the output transistors to the heatsinks did you use insulating hardware and afterwards did you check that your transistors where indeed isolated from the heatsinks you intend to ground? i'm starting to understand infinia's position of seeing the test setup.
turk182:
I don't think this project has any transistors, just the opamp, right? Are you thinking of another thread/project?
I did not insulate the metal screw that fastened the heatsink to the opamp. Did I need to do that? I thought because the chip was coated with plastic, that wouldn't matter. Was I mistaken? Is it better to use one of those PVC/plastic screws?
I don't think this project has any transistors, just the opamp, right? Are you thinking of another thread/project?
I did not insulate the metal screw that fastened the heatsink to the opamp. Did I need to do that? I thought because the chip was coated with plastic, that wouldn't matter. Was I mistaken? Is it better to use one of those PVC/plastic screws?
sorry yes they are chip amps (op amps on steroids) but the same would apply for transistors.
from the technotes for the lm 3886 the tab (that metal back plate with that convenient hole you can put a screw through) is not isolated internally there's a link to V-
and no not a PVC/plastic screw but a combination of a flat mica washer(between the chip and heat sink) and plastic shoulder washer at the hole to isolate the screw
from the technotes for the lm 3886 the tab (that metal back plate with that convenient hole you can put a screw through) is not isolated internally there's a link to V-
and no not a PVC/plastic screw but a combination of a flat mica washer(between the chip and heat sink) and plastic shoulder washer at the hole to isolate the screw
yes it applies to the TF or overture series and if a chip amp was not "sealed" i wouldn't use it.
hey you don't take my word for it verify it yourself you have a multimeter see if there's continuity between the V- (pin 4) and the tab.(no power applied your taking a resistance reading)
and if your next post is going to contain a statement like "how do i find pin 4? which end of the chip do i count from?" i will haze you further about your resistance to learning this "stuff" fair 'nuff.
hey you don't take my word for it verify it yourself you have a multimeter see if there's continuity between the V- (pin 4) and the tab.(no power applied your taking a resistance reading)
and if your next post is going to contain a statement like "how do i find pin 4? which end of the chip do i count from?" i will haze you further about your resistance to learning this "stuff" fair 'nuff.
I don't understand that last post. TF means it's insulated version of same chip, so I'm not srue what you mean.
I also don't understand what you mean by sealed version-I assume you're referring to TF (insulated version) of chip?
Hazing? Sure, if you really feel you have to. Just consider one thing:
You have no idea the challenges I face in my life that prevent me from properly taking the time to learn this stuff really well. It is not a matter of laziness or stuborness or that kind of issue. I used to have the biggest work ethic known to mankind. It is strictly things over which I absolutely have zero control, and no one else in my shoes would either. And when people say "then wait to give this project the time it deserves", I agree, but will likely never be in that kind of position. Just something to consider.
I also don't understand what you mean by sealed version-I assume you're referring to TF (insulated version) of chip?
Hazing? Sure, if you really feel you have to. Just consider one thing:
You have no idea the challenges I face in my life that prevent me from properly taking the time to learn this stuff really well. It is not a matter of laziness or stuborness or that kind of issue. I used to have the biggest work ethic known to mankind. It is strictly things over which I absolutely have zero control, and no one else in my shoes would either. And when people say "then wait to give this project the time it deserves", I agree, but will likely never be in that kind of position. Just something to consider.
I am no longer willing to help the OP he refuses to post an image of his tests. He would rather be spoon feed answers to questions he doesn't even know how to ask. Rather than spending time reading the manual and data sheets he'd rather waste everyone elses time https://youtu.be/1wXs_1V7KiA
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.