Ever when these bias boards work.... I have found ...thay can have diff V. output....I re-work panels on the Summit.. Ascent,i...Odyssey...Prodigy....these panel are a lot ezer to open an not rip the mylar... than the SL3s..Quest.. panels ....but the older panels sound better to me....thay are heaver.....I have a nuff parts now..... to run most my newer ML with the older bias boards...vary hard to work on these boards....well for me...
Also if you can get ML to send you some of the long chips...right by the red LED...Thay were runing out....thay said thay were not making them any more.....I got 2-4.....if that chip gos.....it over for that board less you re-work.........SL3 has same chip...as dose all other ML bias boards I seen....
you need to have some on hand if your going to owne ML...
Also if you can get ML to send you some of the long chips...right by the red LED...Thay were runing out....thay said thay were not making them any more.....I got 2-4.....if that chip gos.....it over for that board less you re-work.........SL3 has same chip...as dose all other ML bias boards I seen....
you need to have some on hand if your going to owne ML...
Last edited:
Yeah, those look to be 1 Watt Zeners so they can dissipate a far amount of heat in normal operation. You confirmed they are working correctly because the AC voltage is being regulated to ~250 Vac. If one or more of the Zeners failed open or closed, the AC voltage you measured at the output of the transformer would be higher or lower respectively.
The diodes and caps may look fine externally, but still can be failed internally. Reading AC voltage across the first capacitor indicates that one of the parts in the first stage of the voltage multiplier is faulty. The diode is easiest to test. It should read open circuit with DVM probes connecting in one direction, and low resistance in the other. If it reads low resistance in both directions, it has failed shorted. If it reads open circuit in both directions it has failed open. You can practice testing the diodes on the good bias board to get a feel for how a good one measures.
The capacitor is tougher to test without special equipment. Substitution is usually easiest.
Another simple test you could do is to bypass the first multiplier section by removing the first diode(temporarily clip one leg which is easily soldered back), and short the first capacitor with a wire soldered between its pins on the back of the PC board. If the rest of the multiplier sections are working, you should get about 2kV output.
I'll try your suggestion this evening. I tested the diodes, didn't just physically examine. My tester showed 5.41v on all diodes, open when reversed.
I have been going to pull the tranfourmer an caps off these boards.... an put my owns bias board togather... bias tranfourmers are the same thay have always used....ezey to do...
all the ML panels as with any ESLs I have work with.. an owend....if the bias feed on all the the time to the panels the sound is better............
Mr bolserst is here with all his help....I don't know what any of us would do with out all his help....getting my minds rapet around this Maze ..these ESL setup can be......thanks to him so much for his time an putting up with us all......
all the ML panels as with any ESLs I have work with.. an owend....if the bias feed on all the the time to the panels the sound is better............
Mr bolserst is here with all his help....I don't know what any of us would do with out all his help....getting my minds rapet around this Maze ..these ESL setup can be......thanks to him so much for his time an putting up with us all......
Last edited:
Hmmmm...interesting. Was this all diodes on the good supply as well?
Those diodes should measure about 0.6v drop in the forward direction.
In any case, if they all measured the same, that would point more toward that first capacitor failing open which seems odd because it is charged to only half the voltage that all the others are. I know many others would say that if you have AC coming into the multiplier and no HV coming out just replace all caps and all diodes and be done with it. I still prefer to try and track down the root cause...but that is just me.
Last edited:
I'll verify again when I get home. I haven't messed with electronics much since school 15 years ago. Most of my equipment hasn't been touched since then. Looking for a decent scope and some other things so I can get back into it as I remove failed AV components for a living.
Should the output of the first cap be DC as I see on the working board? On this problem board I see AC voltage.
And I agree with TYU, thank you for all of your advice to a new guy.
Should the output of the first cap be DC as I see on the working board? On this problem board I see AC voltage.
And I agree with TYU, thank you for all of your advice to a new guy.
Aren't those chips just the LM324 quad opamp?
They are still being produced and available for < $1 from any electronics parts distributor. (Mouser, Digikey, etc...)
Remember, that chip is only for the auto ON/OFF feature, so you can always bypass that 🙂
See first attachment here:
http://www.diyaudio.com/forums/planars-exotics/205136-ground-reference-esls-3.html#post2891710
Yes. The first diode and capacitor form a half wave rectifier, charging the capacitor up to a DC value nearly equal to the positive peak of the AC waveform. There is a pretty good description of how the multiplier works here:
Experiments: Experiment 15
Your very welcome. Just passing it forward 🙂
Should I pick up a cap and diode to swap in? I'm going on a short vacation tomorrow for the weekend, so I'll only have a couple hours tonight to play.
If you can, sure! They shouldn't cost too much. (1N4007 diode, 0.1uF/630V cap)
Since all diodes measured the same for you, I'd try swapping the cap first to see if you then get DC instead of AC voltage across it. If not, then swap the diode as well. With new diode and cap you would definitely be getting DC on the first stage of multiplier then. Whether the rest of the multiplier is functional would remain to be seen.
Since all diodes measured the same for you, I'd try swapping the cap first to see if you then get DC instead of AC voltage across it. If not, then swap the diode as well. With new diode and cap you would definitely be getting DC on the first stage of multiplier then. Whether the rest of the multiplier is functional would remain to be seen.
Because I have no luck but bad, the supply by me is completely out of .1uf caps. Guess we'll try next week.
Well, there is a .1 630 Mylar cap here, but it's the wrong form factor. I'm going to solder this on inline later just to test.
Here's the 'official' replacement:
https://www.madisoundspeakerstore.c...very-26w/4534g-10-aluminum-cone-woofer-4-ohm/
I was incorrect in my voltage reading. 0.521v on all diodes aside from the first two in the ladder. Those are at 0.491v. Just swapped in the new cap and still have AC on both sides. About to put the old one back in and swap diodes. I bought a few of them.
I don't really know anything about those drivers in practice, but I would not hesitate to get a pair of Scan-Speaks even if they were made in China. They should beat the pants off the paper cone Vifa...
I'll probably get a pair on the way shortly.
Back to the board:
Replaced first cap and first two diodes in the ladder. Still not getting DC voltage. Still not seeing a voltage rise, but the frustration level is rising exponentially.
Back to the board:
Replaced first cap and first two diodes in the ladder. Still not getting DC voltage. Still not seeing a voltage rise, but the frustration level is rising exponentially.
Once you get your Ascent working, don't even waste a minute using the stock passive bass xo. Go active xo for the bass, and you'll have some actual bass impact instead of mush.
Just got in from mowing the lawn...something VERY odd is going on.
If you can send me a PM with you phone number I can call you to discuss troubleshooting tactics in about 20 minutes when I am cleaned up.