so, im re-opening this thread!
im tired of the preamp just sitting there collecting dust. i ordered a 1.7 kit from a guy on here, but after 2 months, he has yet to ship it, and still have my money. im still working it all out, he claims it was lost in the mail, but still, it sounds fishy.
anyways, i want this thing fixed and working. i have a scope now! im not entirely sure how to use it, but im pretty sure it works, and i have test leads.
i hooked it up to the wall outlet and looked at the AC voltage coming in from the wall. it looked like a nice sine wave, with just a tiny bit of distortion at the peaks. i went step by step hooking up the preamp. i started with just the transformer, and looked at it through the scope. it looked pretty much the same, nice and smooth lines.
then i hooked up the power supply board. i got +-59v, a little low, but fine. however, i tried to stick the scope probe on it, but all i got was a solid line, no matter how many knobs and dials i messed with. so obviously im doing something wrong there. or maybe it is supposed to look like that. but it was always pretty much perfect.
i hooked up the preamp circuit and measured it all, the voltages are perfect. i put the scope on the output, and same story, straight line. it kicks up and down when the amp turns on an off, but other than that, it looks the same as if the probe wasnt even plugged in...
ill try hooking up a source and see what it sounds like. maybe staying away from it for so long has made it work finally. haha, yeah right.
so, can someone tell me how i can use the scope to diagnose this problem?
im tired of the preamp just sitting there collecting dust. i ordered a 1.7 kit from a guy on here, but after 2 months, he has yet to ship it, and still have my money. im still working it all out, he claims it was lost in the mail, but still, it sounds fishy.
anyways, i want this thing fixed and working. i have a scope now! im not entirely sure how to use it, but im pretty sure it works, and i have test leads.
i hooked it up to the wall outlet and looked at the AC voltage coming in from the wall. it looked like a nice sine wave, with just a tiny bit of distortion at the peaks. i went step by step hooking up the preamp. i started with just the transformer, and looked at it through the scope. it looked pretty much the same, nice and smooth lines.
then i hooked up the power supply board. i got +-59v, a little low, but fine. however, i tried to stick the scope probe on it, but all i got was a solid line, no matter how many knobs and dials i messed with. so obviously im doing something wrong there. or maybe it is supposed to look like that. but it was always pretty much perfect.
i hooked up the preamp circuit and measured it all, the voltages are perfect. i put the scope on the output, and same story, straight line. it kicks up and down when the amp turns on an off, but other than that, it looks the same as if the probe wasnt even plugged in...
ill try hooking up a source and see what it sounds like. maybe staying away from it for so long has made it work finally. haha, yeah right.
so, can someone tell me how i can use the scope to diagnose this problem?
an update:
i threw on an RCA connector for the output on the preamp board and plugged it into an amp i have in my shop that i use for testing. i hooked the scope up to the outputs on the amp. after fiddling with a lot of settings, i got a something that was interesting.
with the preamp off, the scope just shows a pretty much perfect straight flat line. with the preamp on, it goes a little nuts on startup (i get a buzzing at startup through the speakers, so the scope shows this), and then it shows a line that is "decent", but has some bumps in it and is a bit fuzzy or looks kinda like static. its not a perfect line anymore. and when i kick the preamp off again, or unplug it, the line jumps around a bit (turn off thump), and then stabilized to an almost perfect line again.
SO, im seeing whats going on. what can i do from here to troubleshoot? ive checked and rechecked all my components for the most part. i THINK all the components are fine. ive replaced ALL fets twice or more. where should i go from here?
i threw on an RCA connector for the output on the preamp board and plugged it into an amp i have in my shop that i use for testing. i hooked the scope up to the outputs on the amp. after fiddling with a lot of settings, i got a something that was interesting.
with the preamp off, the scope just shows a pretty much perfect straight flat line. with the preamp on, it goes a little nuts on startup (i get a buzzing at startup through the speakers, so the scope shows this), and then it shows a line that is "decent", but has some bumps in it and is a bit fuzzy or looks kinda like static. its not a perfect line anymore. and when i kick the preamp off again, or unplug it, the line jumps around a bit (turn off thump), and then stabilized to an almost perfect line again.
SO, im seeing whats going on. what can i do from here to troubleshoot? ive checked and rechecked all my components for the most part. i THINK all the components are fine. ive replaced ALL fets twice or more. where should i go from here?
scope lesson#1
1. If your bosoz is making 60hz humming noise, you should be able to see it on the scope, turn your timebase down to 60hz, which is about 1/60= 16.6ms/div, so use 20 or 10ms/div. Your trace will slow down, as it goes across the screen.
then turn your v/div on the input amps up till you see the hum as a pattern of waves or partial waves on the screen.
2. turning up the v/div on the input amps will show you all the noise that is there, the straight line will not be so straight after all once you start cranking the amp. However, you have to play with the timebase to learn where the noise is in frequency as HF and LF noise cannot be seen on the low/fast speed (ns) settings.
3. If you want to see AC make sure you select "AC couple" the waveform will not shift position if there is DC on it. this is good to look at the noise on your 60V rails, for example. You may want to see if noise is coming in from your power rails, check them out, if they have bumps then your MOSFETs are probably working right, your power supply might be bleeding the AC to the circuit.
4. You might want to look at the output and rails/input simultaneously on the screen to see if the bumps are happenning at the same time or not in the ps and amp circ.
did this help?
cowanrg said:
1. If your bosoz is making 60hz humming noise, you should be able to see it on the scope, turn your timebase down to 60hz, which is about 1/60= 16.6ms/div, so use 20 or 10ms/div. Your trace will slow down, as it goes across the screen.
then turn your v/div on the input amps up till you see the hum as a pattern of waves or partial waves on the screen.
2. turning up the v/div on the input amps will show you all the noise that is there, the straight line will not be so straight after all once you start cranking the amp. However, you have to play with the timebase to learn where the noise is in frequency as HF and LF noise cannot be seen on the low/fast speed (ns) settings.
3. If you want to see AC make sure you select "AC couple" the waveform will not shift position if there is DC on it. this is good to look at the noise on your 60V rails, for example. You may want to see if noise is coming in from your power rails, check them out, if they have bumps then your MOSFETs are probably working right, your power supply might be bleeding the AC to the circuit.
4. You might want to look at the output and rails/input simultaneously on the screen to see if the bumps are happenning at the same time or not in the ps and amp circ.
did this help?
cowanrg said:
Hi cowanrg, I too hope to get a scope soon, in the meantime I have been reading/studying on which ones to get on Ebay. I found a great tutorial from Tektronics on oscilloscopes that may be helpful.
http://www.tek.com/Measurement/cgi-...rement/App_Notes/XYZs/&FrameSet=oscilloscopes
Stan
thanks for the help guys. unfortunately, i cannot see ANYTHING connected just to the preamp itself. it always shows a straight line, no matter how many knobs and dials i turn. this is also true for my meter, the meter registers almost no voltage out on the preamp. in theory, its quite.
however, here is what i see when hooking it up to an amplifier:
(no making fun of my scope)
however, here is what i see when hooking it up to an amplifier:
(no making fun of my scope)
Attachments
this is with no input into the preamp at all. the phoenix connectors are completely empty. the outputs just a single rca going from + and GND to an RCA jack. then, an interconnect connects that RCA to the amplifier. i put the probe at the positive output of the amp's speaker terminal. i could of course be picking up noise from the amp itself, but without the preamp connected, there is just a straight line. so, the preamp is introducing it.
it SEEMS like its a ground loop issue, but ive tried everything. ive lifted grounds, ive shorted inputs, etc... it never goes away. and the preamp board is almost 2 feet away from the transformer, etc... this is a perfect test condition. and the power supply appears to be pretty clean.
the settings i used are: 1ms/cm, .05 v/cm, AC input.
i hope that tells someone SOMETHING. i just found a very small plitron transformer at a surplus shop. its rated at 30 watts and has 55v secondaries i believe. im going to make a small power supply using that, a couple bridge rectifiers, and some caps. i will get rid of the regulated supply and xformer, as they might be the issue. ill see if i still have noise then.
it SEEMS like its a ground loop issue, but ive tried everything. ive lifted grounds, ive shorted inputs, etc... it never goes away. and the preamp board is almost 2 feet away from the transformer, etc... this is a perfect test condition. and the power supply appears to be pretty clean.
the settings i used are: 1ms/cm, .05 v/cm, AC input.
i hope that tells someone SOMETHING. i just found a very small plitron transformer at a surplus shop. its rated at 30 watts and has 55v secondaries i believe. im going to make a small power supply using that, a couple bridge rectifiers, and some caps. i will get rid of the regulated supply and xformer, as they might be the issue. ill see if i still have noise then.
well, well, well.
i finally used a completely different power supply and the results are interesting. previously, i used the transformer that was in the original build and removed the PSU boards and just made a simple linear unregulated supply. i had the same results as with the regulated PSU boards.
well, it was said that it could be the transformer causing the issues because it was so oversized. i used this little 30 watter i got to test that theory. in the writeup for the bosoz, nelson says that you can use 30-60v rails, but at 60v, you get lowest distortion. this transformer gave me 30v rails loaded. i just used a single bridge rectifier and a pair of smaller value caps. nothing fancy at all.
the exact same noise was still there, but now it was louder. that was probably due to the lower voltage supply, and noisier supply. here is what it looked like (is that what oscillation looks like?):
i finally used a completely different power supply and the results are interesting. previously, i used the transformer that was in the original build and removed the PSU boards and just made a simple linear unregulated supply. i had the same results as with the regulated PSU boards.
well, it was said that it could be the transformer causing the issues because it was so oversized. i used this little 30 watter i got to test that theory. in the writeup for the bosoz, nelson says that you can use 30-60v rails, but at 60v, you get lowest distortion. this transformer gave me 30v rails loaded. i just used a single bridge rectifier and a pair of smaller value caps. nothing fancy at all.
the exact same noise was still there, but now it was louder. that was probably due to the lower voltage supply, and noisier supply. here is what it looked like (is that what oscillation looks like?):
Attachments
cowanrq,
Well I don't know exactly what "WBT" means. If it means "water-based-something" then yeah... you need to wash these boards.
Lemme 'spain Rucy... Good ole Kester 44 and most other solders use a pine tar/oil based flux... it smells like pine when you use it. This stuff is non-conductive and can be left on the circuits forever without any harm (at least that is what we know after 100 years or so)
OTOH, water based fluxes are very conductive; so it's like having a bunch of 200K resistors connecting every point in your amp to every other point. Better still, it is mildly corrosive; so it eats away at your connections if left on the boards.
This is just a wild guess... but it sounds like that is where your at.
Go to their website... and post the link for us... give us the brand, part number and all that for the solder your using.
If you're just starting out building electronics... try to stay away from exotics... in just about anything. I am all about gold plated connectors simply because they don't rot; but I won't pay alot for them (10 cents worth of gold). Beyond that, the only people who can hear a difference are the people that actually spent a pile of money on something questionable.
Let us know about your solder... and we'll line you how on how to clean your boards... IF you need to.
Well I don't know exactly what "WBT" means. If it means "water-based-something" then yeah... you need to wash these boards.
Lemme 'spain Rucy... Good ole Kester 44 and most other solders use a pine tar/oil based flux... it smells like pine when you use it. This stuff is non-conductive and can be left on the circuits forever without any harm (at least that is what we know after 100 years or so)
OTOH, water based fluxes are very conductive; so it's like having a bunch of 200K resistors connecting every point in your amp to every other point. Better still, it is mildly corrosive; so it eats away at your connections if left on the boards.
This is just a wild guess... but it sounds like that is where your at.
Go to their website... and post the link for us... give us the brand, part number and all that for the solder your using.
If you're just starting out building electronics... try to stay away from exotics... in just about anything. I am all about gold plated connectors simply because they don't rot; but I won't pay alot for them (10 cents worth of gold). Beyond that, the only people who can hear a difference are the people that actually spent a pile of money on something questionable.
Let us know about your solder... and we'll line you how on how to clean your boards... IF you need to.
ok, here is the exact solder i used for the preamp and PSU boards:
http://www.wbtusa.com/wbtsilversolder.htm
ive used it for two working aleph3 monoblocks, a 2-ch gainclone, some stepper motor controller boards, and several other things.
i also have some backup solder that i use, which is kester "44" rosin core. the label is worn off, so i cant tell much more than that.
i have a VERY hard time believing that is the cause. BUT, its not the power supply, or the power supply boards, and both channels of the preamp are doing the same thing, so maybe it is...
http://www.wbtusa.com/wbtsilversolder.htm
ive used it for two working aleph3 monoblocks, a 2-ch gainclone, some stepper motor controller boards, and several other things.
i also have some backup solder that i use, which is kester "44" rosin core. the label is worn off, so i cant tell much more than that.
i have a VERY hard time believing that is the cause. BUT, its not the power supply, or the power supply boards, and both channels of the preamp are doing the same thing, so maybe it is...
OK,
For openers, WBT doesn't have a "spec sheet" on their product, the solder. In my book, that makes it a "non product" right out of the gate... looked like some audiophile cr4p there too. I would stay away, save your money, and deal with professional product. I don't know if your boards should be washed or not... you might send them an email and find out. I do agree, with the other amps working that flux is probably NOT the problem. Never hurts to clean your boards though... problem IS, don't know what to clean with... no specs. They are buying this from some one else... slapping on their label... charging 4 times more for it... and concealing the specs so other people won't match specs and find out it is just Kester, or the normal German brand solder being relabeled. Try to stay away from products and websites that don't have specs... not professional grade... you want tuna that tastes good.
I read back through the thread again. You changed power supplies and still the same problem. But your waveforms imply a hum problem.
The most telling thing in the whole thread was the fact that you could alter the input connections and change the noise problem. Ah-ha????
Can you post a schematic or link. I don't follow all threads and "fashions" etc...
For openers, WBT doesn't have a "spec sheet" on their product, the solder. In my book, that makes it a "non product" right out of the gate... looked like some audiophile cr4p there too. I would stay away, save your money, and deal with professional product. I don't know if your boards should be washed or not... you might send them an email and find out. I do agree, with the other amps working that flux is probably NOT the problem. Never hurts to clean your boards though... problem IS, don't know what to clean with... no specs. They are buying this from some one else... slapping on their label... charging 4 times more for it... and concealing the specs so other people won't match specs and find out it is just Kester, or the normal German brand solder being relabeled. Try to stay away from products and websites that don't have specs... not professional grade... you want tuna that tastes good.
I read back through the thread again. You changed power supplies and still the same problem. But your waveforms imply a hum problem.
The most telling thing in the whole thread was the fact that you could alter the input connections and change the noise problem. Ah-ha????
Can you post a schematic or link. I don't follow all threads and "fashions" etc...
Hi,
WBT is a German brand wich also makes all sorts of cinch and loudspeaker connectors. I´ve used their solder quite often without any problems (it smells very nice )
Since both of your boards do the same thing the mistake must be one that is constructed in and not a faulty part.
Since the schematic is very simple you could check the boards point to point if they comply with the schematics.
William
WBT is a German brand wich also makes all sorts of cinch and loudspeaker connectors. I´ve used their solder quite often without any problems (it smells very nice
)Since both of your boards do the same thing the mistake must be one that is constructed in and not a faulty part.
Since the schematic is very simple you could check the boards point to point if they comply with the schematics.
William
plenty of people on here use the WBT solder, its pretty popular. i got it off a recommendation about 2 years before poobah became a member! hehe. i didnt get it for sonics, etc.. i got it because its really easy to work with and melts at a low temerature. it isnt that expensive if you know where to buy it, and it truly solders a LOT better than the kester i use otherwise.
ive built to many things with it to think that its the solder thats causing the problem.
here is the schematic again:
http://www.kk-pcb.com/bls.html
the board and schematic are there.
here is a link to the full writeup from nelson pass. he includes a service manual that has voltages to check. im getting almost exact values at the spots. the schematic is on page 4. im getting within 1% or so of all the values given.
http://www.passdiy.com/pdf/balzenpre.pdf
this is why its so confusing to me!!!
poobah, you said this:
"The most telling thing in the whole thread was the fact that you could alter the input connections and change the noise problem. Ah-ha????"
where did you see that? all the noise you are seeing on this post is without a single thing connected at the input. i will try shorting the input to see if it changes things (ive done it before, but not with a scope). could you maybe show me the post where i said this? there are about 3 threads with 10+ pages of posts of this problem alone
ive been trying to fix it for about a year now.
ive built to many things with it to think that its the solder thats causing the problem.
here is the schematic again:
http://www.kk-pcb.com/bls.html
the board and schematic are there.
here is a link to the full writeup from nelson pass. he includes a service manual that has voltages to check. im getting almost exact values at the spots. the schematic is on page 4. im getting within 1% or so of all the values given.
http://www.passdiy.com/pdf/balzenpre.pdf
this is why its so confusing to me!!!
poobah, you said this:
"The most telling thing in the whole thread was the fact that you could alter the input connections and change the noise problem. Ah-ha????"
where did you see that? all the noise you are seeing on this post is without a single thing connected at the input. i will try shorting the input to see if it changes things (ive done it before, but not with a scope). could you maybe show me the post where i said this? there are about 3 threads with 10+ pages of posts of this problem alone
ive been trying to fix it for about a year now.
Well, enough about the solder. BTW, I was designing amps before the web existed... excuse the 2 months on DYI please.
Geeze there is nothing to this thing! Shouldn't be that hard.
Rig up 2 connectors for the input (cheap ones) just make a short circuit... "tip to ring". Short the inputs, read the outputs and listen... tell us what you get.
Geeze there is nothing to this thing! Shouldn't be that hard.
Rig up 2 connectors for the input (cheap ones) just make a short circuit... "tip to ring". Short the inputs, read the outputs and listen... tell us what you get.
poobah said:Well, enough about the solder. BTW, I was designing amps before the web existed... excuse the 2 months on DYI please.
Geeze there is nothing to this thing! Shouldn't be that hard.
Rig up 2 connectors for the input (cheap ones) just make a short circuit... "tip to ring". Short the inputs, read the outputs and listen... tell us what you get.
thats exactly what i was going to try.
oh, and i wasnt at ALL trying to call you a newbie. just to show that many people on here use WBT solder, and its popular, and im sure its not the problem. thats all. you know more than me at this, yet you've only been registered here for a few months, me, a few years. it doesnt relate in any way to knowledge.
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