Kleos - Dipole Line Array

[Hank]

Find that dad-blamed short or ship the board to me. :

[Johnloudb]

Find that dad-blamed short or ship the board to me. :

I hear ya Hank!

The trace leading to the capacitance multiplier -


The end of that trace, connecting to R100 -


The pad on the left is output of voltage regulator, now cut. do see some discoloration there, but I scraped around the pad ... don't think that the short.




Hank, going to put JFETs in the other board and give it a quick test this weekend. Everyone knows this project would nowhere without you kicking me in pants. Sure if anyone wants to check out this board, you're welcome to. Think I'm done, will send it to ya.

[5th element]

Glowing fluorescent PCBs, what sorcery is this!

Edit - I want some.

[Johnloudb]

Glowing fluorescent PCBs, what sorcery is this!

Edit - I want some.

Lol, it's backlit with a flashlight, so I check it out easier. But it is kind of cool looking. Could add led backlighting and a transparent cover on a nice case I suppose ... Must get everything working first!

[5th element]

Oh I see you've got the copper etched off on both sides of the PCB around the traces, so that if you shine a light in from one side it illuminates the material the board is made of and makes the area around the traces shine. It does look pretty cool.

[monzanut]

It looks like you are almost there. Assuming you haven't already found the short I have a couple of points that might help:

1) Is the 'short' actually a dead short? Have you measured with a meter?
2) If it is a dead short the easiest way to find out where it is after you've done your visual inspection is to hook that rail up to a high current power supply at less than or equal to the voltage that rail would normally run at. A PSU with a variable current limit is ideal, at a pinch a lead-acid battery will do. Remember to use short heavy gauge wires to avoid limiting the current. This will most probably blow out your short (if its pretty small) or at least highlight it by heating up that bit of the board.
3) If it is not a dead short (~0 ohm) the value will give you an idea of where to look. If its similar to any of your resistor values look around those areas etc...

The speakers look great by the way. I have been following this thread for a while and am impressed by how long you have kept going.

[Hank]

John, if you haven't seen anything yet, the short could well be a solder bridge underneath a component, so that it's hidden. I'm a smoke test kinda guy, so I agree with monzanut's recommendation.

[Johnloudb]

Oh I see you've got the copper etched off on both sides of the PCB around the traces, so that if you shine a light in from one side it illuminates the material the board is made of and makes the area around the traces shine. It does look pretty cool.

Yep, no solder mask on this and no ground plane on the bottom to block the light.

[eb15]

I don't know if this is your problem, but when I worked on some projects 30 years ago, I'd was hit by
where the regulator heat sink tab was internally connected somewhere other than where I thought
it was connected causing a short circuit when it was mounted.
And also positive and negative regulators have differing pinouts which didn't mirror each other.

I'd double check the pinouts there. Pull it out completely and see if there's still a short.

-
Ed

[Johnloudb]

It looks like you are almost there. Assuming you haven't already found the short I have a couple of points that might help:

1) Is the 'short' actually a dead short? Have you measured with a meter?
2) If it is a dead short the easiest way to find out where it is after you've done your visual inspection is to hook that rail up to a high current power supply at less than or equal to the voltage that rail would normally run at. A PSU with a variable current limit is ideal, at a pinch a lead-acid battery will do. Remember to use short heavy gauge wires to avoid limiting the current. This will most probably blow out your short (if its pretty small) or at least highlight it by heating up that bit of the board.
3) If it is not a dead short (~0 ohm) the value will give you an idea of where to look. If its similar to any of your resistor values look around those areas etc...

The speakers look great by the way. I have been following this thread for a while and am impressed by how long you have kept going.

I tried to reply to you and Hank yesterday but the post got lost somehow and didn't have time to do it again.

It is a dead short.

I've measured the resistance across R100 and it measures 1.8k which is exactly R100 and R101 in parallel which it should be if the output of regulator is shorted. So the resistors are okay.

So, monzanut and Hank, I'll take one last look at the board and then I'll try to start a fire. The only component left were there could be a short under it is R100, and I see anything short there.

So, I got 4D batteries stapped together, 6 volts ... Video later tonight. Eye protection and a clear glass bowl will be over the batteries.

John

[Johnloudb]

I don't know if this is your problem, but when I worked on some projects 30 years ago, I'd was hit by
where the regulator heat sink tab was internally connected somewhere other than where I thought
it was connected causing a short circuit when it was mounted.
And also positive and negative regulators have differing pinouts which didn't mirror each other.

I'd double check the pinouts there. Pull it out completely and see if there's still a short.

-
Ed

Thanks Ed, the heat sinks aren't touching the board or any other pins other than the back tab. So , I think I'm fine there. And the power supply of my other board works fine.

[JonP]

I tried to reply to you and Hank yesterday but the post got lost somehow and didn't have time to do it again.

It is a dead short.

I've measured the resistance across R100 and it measures 1.8k which is exactly R100 and R101 in parallel which it should be if the output of regulator is shorted. So the resistors are okay.

So, monzanut and Hank, I'll take one last look at the board and then I'll try to start a fire. The only component left were there could be a short under it is R100, and I see anything short there.

So, I got 4D batteries stapped together, 6 volts ... Video later tonight. Eye protection and a clear glass bowl will be over the batteries.

John

Wow, this sounds interesting... D batteries are good for many 10's of amps, that's what you need if you dont' have a power supply for that.. (most don't) What you also should have, is a good meter with a mV scale, so you can do something like run 5-10A in momentary bursts, and probe around measuring millivolts here and there during those times, to figure out where the short is.

I was doing something like this, both with a >10A power supply, and then to clear it, with a really big cap and a higher voltage supply on a batch of PCB's with a short. Back in the day, you'd occasionally get a board with a hair, or dust or whatever on the photoresist... causing an extraneous hair of copper on the board to short something out. Guess this is still possible. The cap, big enough and charged up enough, would blow that tiny bridge, just vaporize the short. If you were lucky, that is...

So, some times you could fix them. I'd guess the cap effect would help more than straight current, so if you have 5, 10, 15KuF at your voltage, I'd give that a shot too, on a 20, 30, 50V power supply... If that doesn't clear it, it's too big and solid to fix... If it's big and solid, and you can find it... well, then an xacto knife is your friend...

Good luck!

[Johnloudb]

Wow, this sounds interesting... D batteries are good for many 10's of amps, that's what you need if you dont' have a power supply for that.. (most don't) What you also should have, is a good meter with a mV scale, so you can do something like run 5-10A in momentary bursts, and probe around measuring millivolts here and there during those times, to figure out where the short is.

I was doing something like this, both with a >10A power supply, and then to clear it, with a really big cap and a higher voltage supply on a batch of PCB's with a short. Back in the day, you'd occasionally get a board with a hair, or dust or whatever on the photoresist... causing an extraneous hair of copper on the board to short something out. Guess this is still possible. The cap, big enough and charged up enough, would blow that tiny bridge, just vaporize the short. If you were lucky, that is...

So, some times you could fix them. I'd guess the cap effect would help more than straight current, so if you have 5, 10, 15KuF at your voltage, I'd give that a shot too, on a 20, 30, 50V power supply... If that doesn't clear it, it's too big and solid to fix... If it's big and solid, and you can find it... well, then an xacto knife is your friend...

Good luck!

Good thoughts JonP! Hmmm ... I've got a couple old 13,000uF , 75v mallory's from an old amplifier. Got a power supply that will charge those up 45 volts! That should juice the board pretty good!

I'm worried I missed something on the board but how could I? just two traces on the back that are nowhere close to a ground and the traces I posted above. There is just no path to ground I can see .... anyway, let's see if I can blow something up today.

John

[JonMarsh]

This makes me shudder to read about... :W

But you know, for a new board, I often build it in stages, testing as I go along... sorry I don't have anything else helpful to offer.

[Johnloudb]

This makes me shudder to read about... :W

But you know, for a new board, I often build it in stages, testing as I go along... sorry I don't have anything else helpful to offer.

Yeah, I should have build in stages starting with the power supply, and I considered doing that ...

Anyway, I have news ... Pics and video coming later tonight ... No spoilers!

[Johnloudb]

Okay, are some pics of my setup:

Make note of the large caps and blue 3M Tape which held them together nicely!!!


Charging up through resistor, parallel LED circuit shows when charging.


Here is the pad before -


Here is the pad after -


So, looks like a bad pad to me. Like the copper wasn't completely etched off around the pad. The trace is partly fried too on one side but the short is gone!!! The resistance across R100 is now 2.7k as it should be, and the trace and pad are still good!!! yay, thanks for the suggestions guys!

I have video but haven't been able to upload it to Dropbox for some reason. But will post as soon as I get it up loaded somewhere.

Now how do I put all the caps I pulled out back in. These are plated through holes and desoldering wick is useless. Well, have to get creative I guess.

[5th element]

So you fixed the short by throwing tons of power through it and it melted? LOL I like this method.

[Johnloudb]

So you fixed the short by throwing tons of power through it and it melted? LOL I like this method.

Yeah, I perhaps over did a bit with the power, cleared it good and almost took out the trace and pad. But who knows, it may have done that regardless. Big flash, and would like to post a link to the video if I can ever get it uploaded somewhere.

OT, Just came home from the grocery and this fire engine with lights and siren going went through a red light when I was waiting to turn. So I turned and followed a ways back behind him, and he goes 20 miles per hour and takes up two lanes (must been a real emergency!) and of course you don't pass a fire engine ... And a funeral procession builds behind him till he turns off onto the freeway, still slowly. WTF

Perahaps he was having some kind of health problem and that was the emergency?!!! Haha ... You think I care, "get off the damn road!"

[Hank]

I love it! Power, flash, smoke, explosion. Brute force is way more fun than delicate probing any day. And, that blue tape survived unscathed, no doubt.

[Johnloudb]

I love it! Power, flash, smoke, explosion. Brute force is way more fun than delicate probing any day. And, that blue tape survived unscathed, no doubt.

I agree! just hope there's no more problems with the board. I was surprised that there was a defect like that.

[monzanut]

Glad that the tip helped. You applied quite a bit more energy than I had envisaged, but if it works then all good! On finer boards you can use less current and a thermal camera, although that requires a thermal camera that most people don't have just lying around!

Now how do I put all the caps I pulled out back in. These are plated through holes and desoldering wick is useless. Well, have to get creative I guess.

Two thoughts:

Solder wick can work a lot better if you "wet" it with more solder, hold the wick over the hole apply heat from the iron and when you start to see the solder being wicked up add a little bit more solder to the back of the wick. It sounds counter-intuitive, but it seems to suck the solder out of the hole. Also if you can arrange the wick so it is partially overlapping the hole you'll be able to see when it is clear. Also leaded solder is pretty much a must here unless you have a super-hot iron.

Failing that, just heat up the solder in the holes already and push the component legs through the molten solder. Two irons can be handy here :-). Once you have the part in resolder with fresh solder to ensure a nice shiny joint.

[BobEllis]

I use a solder sucker on through plated holes - I suspect a shot of compressed air on a properly heated blob of solder would work to blow it out of the hole as well.

[Johnloudb]

Great ideas guys! Okay I have a solder sucker like that and think I have a plan for it that might work, we'll see what happens but with this kind of support surely something will.

[BobEllis]

I forgot to mention that before the solder sucker I use a wick to remove as much solder as possible. Essentially what I suck out is a plug the size of the through hole. Use a hotter than normal iron and work quickly - melt the solder and get it out and stop heating the board.

[Johnloudb]

I forgot to mention that before the solder sucker I use a wick to remove as much solder as possible. Essentially what I suck out is a plug the size of the through hole. Use a hotter than normal iron and work quickly - melt the solder and get it out and stop heating the board.

Thanks Bob! Well, I burned myself with the soldering iron and got fed up for a bit and then got busy with my photography class and other stuff. But, I've got to get this done before school starts in late August so going to try to focus more on this and finish it up.

So, the End is near ... I promise everyone in the world that that I'll have both up and running before school.

[Hank]

If both are not up and running and you have not posted measurements and a listening review, Jon and I shall perform an interdiction in the middle of the night in a white van, abduct the speakers and crossovers and sell it all out of the back of the van the next day in a WalMart parking lot.:dance:

[Johnloudb]

If both are not up and running and you have not posted measurements and a listening review, Jon and I shall perform an interdiction in the middle of the night in a white van, abduct the speakers and crossovers and sell it all out of the back of the van the next day in a WalMart parking lot.:dance:

Understood Hank, The pressure is on! Perhaps I could suggest an alternate plan ... maybe you and Jon show up in a white van with measurement equipment and tools ... Fix my crossover, measure and optimize my loudspeaker and we all sit down for a nice listening session. Drinks are on me!!!

No worries ... I'll get it done!

[Hank]

Send me your address and I'll send you my OmniMic so you can measure to your heart's content :righton:

[JonMarsh]

Understood Hank, The pressure is on! Perhaps I could suggest an alternate plan ... maybe you and Jon show up in a white van with measurement equipment and tools ... Fix my crossover, measure and optimize my loudspeaker and we all sit down for a nice listening session. Drinks are on me!!!

No worries ... I'll get it done!

If necessary, we'll enlist Evil Twin to help.... :B

[JonMarsh]

Thanks Bob! Well, I burned myself with the soldering iron and got fed up for a bit and then got busy with my photography class and other stuff. But, I've got to get this done before school starts in late August so going to try to focus more on this and finish it up.

So, the End is near ... I promise everyone in the world that that I'll have both up and running before school.

Should we run a little friendly side wager whether you succeed in procrastinating longer with these than I will with the Wavecor Ardents? I think Ben and his Dad will run an interdiction on me if I don't have things finalized soon!

I'm spotting you two weeks as I have to leave this Wednesday until the 10th for my GF's niece's wedding... that's a pretty good handicap!

[Johnloudb]

Should we run a little friendly side wager whether you succeed in procrastinating longer with these than I will with the Wavecor Ardents? I think Ben and his Dad will run an interdiction on me if I don't have things finalized soon!

I'm spotting you two weeks as I have to leave this Wednesday until the 10th for my GF's niece's wedding... that's a pretty good handicap!

Haha, car repairs ... i.e. Performance lowering springs and shocks have left me pretty dry, but okay a small wager. Anything to keep Evil Twin from showing up on my doorstep!

How about the loser buys the winner a CD title of their choice?
Oh yeah, can't chose some 'spensive esoteric CD either, $15.00 max!

Well, to update I'm waiting on some replacement caps, should be here today. Got to get this done in two weeks!

[JonMarsh]

How about the loser buys the winner a CD title of their choice?
Oh yeah, can't chose some 'spensive esoteric CD either, $15.00 max!

Well, to update I'm waiting on some replacement caps, should be here today. Got to get this done in two weeks!

You think you're dry? How about me having just bought a new VFR1200, a new Corbin seat, OEM panniers, and a rear carrier rack? Oh, and Helibars and Knight Design Pegs, and a Leo Vince exhaust on order? Now THAT's being DRY! My pocket book is squealing like a lab mouse while getting a shot!

OK, I like your terms.... DONE! this is one I can afford to lose- just remember, you've got a two week handicap on me! Pressure's ON!

[Hank]

Side wager? I'll take a piece of that action. Don't you boys forget who the King of Procrastination is. I've forgotten how many years it's been since I "planned" to do an OBLA. I wear my crown proudly. I'm sure enjoying my "new" Acoustat model 3's. I don't suppose anyone else on this forum owns electrostats - you're all cones and domes, right?

[Johnloudb]

Side wager? I'll take a piece of that action.

I'm okay with that. So, how does that work? If you bet Jon and I win, then both you and Jon buy me a different CD? If you bet on me and I win, then Jon buys us both a CD.

There are other scenarios but I'm trying to stay positive.

Glad you're enjoying your Acoustats! Did you get them modded yet?

John

[JonMarsh]

I once owned a set of Maggies, and if I was to buy something manufactured, the 3.7's would be on my short list.

[Hank]

John, I've finally got all the parts in - latest are high voltage diodes - going to replace the voltage multiplier board caps and diodes. Probably don't need to, but 1981 build makes me think that aging may subject the old parts to failure - would probably make some nice fireworks. Plus the requisite modern film caps to replace the other caps in the interfaces, plus big honking HV resistors, plus military high purity copper/teflon insulated wire.

Jon: if you go planar, you need to compare Maggies to the latest electrostats or used Acoustats and upgrade the interfaces with better caps, resistors and internal wire. You just might be a convert. But with either planar type, you'd have to face the GAF factor :W

[Johnloudb]

That sounds great Hank ... I would worry about the old caps too. Just as soon as I get done here I'll start nudging you to get that done. Return the favor so to speak

Well I have some good news ... One board is powered up, and all looks good - supply voltage, bias currents, dc offset, but won't know for sure till I hook it up to a scope.

The caps I thought I ordered, didn't get ordered, mistakenly didn't finish the order but they are on the way now. I installed the JFETs in the other board and that's the one that is powered up. So feeling good!

[JonMarsh]

John, I've finally got all the parts in - latest are high voltage diodes - going to replace the voltage multiplier board caps and diodes. Probably don't need to, but 1981 build makes me think that aging may subject the old parts to failure - would probably make some nice fireworks. Plus the requisite modern film caps to replace the other caps in the interfaces, plus big honking HV resistors, plus military high purity copper/teflon insulated wire.

Jon: if you go planar, you need to compare Maggies to the latest electrostats or used Acoustats and upgrade the interfaces with better caps, resistors and internal wire. You just might be a convert. But with either planar type, you'd have to face the GAF factor :W

I used to sell Acoustats, and am pretty familiar with the set Thomas has. Both would be a bit of a GAF challenge, again, due to optimum placement issues. OTOH, I showed pictures of the 1.6's to GF for one of her GF's, and she thought they looked nice. Maybe not much of a challenge.... :W

I fully concur with the notion of rebuilding your HV electronics BEFORE something bad happens... the Acoustat panels are very rugged, though, compared with most.

[Johnloudb]

Murphy's Law is giving me fits, a real battle going on here ... It's getting dark ... But it's always darkest before the Dawn! Details later ...

[Johnloudb]

Murphy's Law is giving me fits, a real battle going on here ... It's getting dark ... But it's always darkest before the Dawn! Details later ...

Well, the board I had working quit working, developed a lot of DC at the output of two of the JFET pairs, I assumed broken JFETs and replaced the two pairs but the problem persisted. So, I snooped around with my multimeter and found the gate resisted was an open circuit to the rest of the circuit, so the gate floating eventually causing the JFET to latch up to the positive rail. It looked soldered well but it was not a good electrical connection and I fixed that. Similar problem with the other one but with the resistor that provided the path to ground. It was connected with silclear for a temporary connection and fixed that too.

Anywho, have been thinking about whether I should just solder those silcleared parts in but I decided not too, at least until I get one speaker up and running in the room location where they'll be. I'll test this out board out in my scope when I get back home. At the auto shop now.

[JonMarsh]

For new hardware, I always recommend a thorough scope test, followed by 24 hour burn in, and another scope test. keep at it, you'll get there eventually!

[Johnloudb]

For new hardware, I always recommend a thorough scope test, followed by 24 hour burn in, and another scope test. keep at it, you'll get there eventually!

Thanks, didn't get to that yesterday but will check it out this morning and then let it burn in.

[Johnloudb]

Just keeps getting better and better. Good news is the high pass filter works as it should! Yay!

But the low pass filter is shorted just before the gate resistor of the second JFET pair. Like the other short there is no visible short ... I took out the Wima filter caps which were not soldered and checked all around that node front and back of board. I've isolated the short to a particular pad, and like the other one it looks perfectly fine all the way around. I took a pic but can't post it from my phone. So going to blow the sucker, with just 9v this time, so I don't my damage any parts. More to come ...

[Johnloudb]

That was easy, just 10 volts and a 10,000uF cap cleared it. No sparks or anything.

[JonMarsh]

Man, no sparks? That's no fun... there's a reason I call electronics wires and sparks, you know... gotta have both!