And to be perfectly clear what I bought was a meter with the ability to test capacitance. I already have two other meters. I'm not a complete novice.
So like I said I checked all of the caps and they are all within 5%. I tested the output of the transformer and I get 530 volts and 364 volts with my neg test lead on the top solder joint I the photos and the the positive on the next one down and then the one below that next.
Thanks
Eric
So like I said I checked all of the caps and they are all within 5%. I tested the output of the transformer and I get 530 volts and 364 volts with my neg test lead on the top solder joint I the photos and the the positive on the next one down and then the one below that next.
Thanks
Eric
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Okay that's Cool.
What is the voltage after the resistor feeding the Mutiplier?
jer
Straight out of the transformer taps.
Thanks
Eric
Okay then the supply is working that is what we needed to find out.
The reason you only measured about 330v or so with your meter was becuase your meters internal resistance formed a voltage divider with the High valued resistors that are already on the board.
If you only got 1mm to 2mm of an arc out of it, this explains the lower output of 2.4Kv or so, as I was expecting much more.
Then the next step would be to measure the step-up transfomer and see if it is working correctly.
You can do this by feeding a test tone to your amp connected to the input of transformer with or without the crossover.
Without would be a better choice.
Set your test tone to about 100Hz to 200Hz at 1Vrms into the primary of the transformer.
Most meters are okay with this frequency range.
Then measure the voltage coming out of the transformer and it should be stepped-up and the output voltage will reflect what the step up ratio is, as measured from the wires going to the stator's.
Make sure that you don't use any input voltage greater than about 2Vrms for two reasons.
#1~With a 2V input your output would/could be as high as 200Vrms or more.
#2~ We don't know what the designed saturation point is for that transformer and more voltage at that low of a frequency could cause it to saturate.
There may very well be a problem with the panels coating itself as this happens a lot with ML's.
But we must first make sure that it is getting the required driving voltages.
jer
The reason you only measured about 330v or so with your meter was becuase your meters internal resistance formed a voltage divider with the High valued resistors that are already on the board.
If you only got 1mm to 2mm of an arc out of it, this explains the lower output of 2.4Kv or so, as I was expecting much more.
Then the next step would be to measure the step-up transfomer and see if it is working correctly.
You can do this by feeding a test tone to your amp connected to the input of transformer with or without the crossover.
Without would be a better choice.
Set your test tone to about 100Hz to 200Hz at 1Vrms into the primary of the transformer.
Most meters are okay with this frequency range.
Then measure the voltage coming out of the transformer and it should be stepped-up and the output voltage will reflect what the step up ratio is, as measured from the wires going to the stator's.
Make sure that you don't use any input voltage greater than about 2Vrms for two reasons.
#1~With a 2V input your output would/could be as high as 200Vrms or more.
#2~ We don't know what the designed saturation point is for that transformer and more voltage at that low of a frequency could cause it to saturate.
There may very well be a problem with the panels coating itself as this happens a lot with ML's.
But we must first make sure that it is getting the required driving voltages.
jer
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To protect your amplifier when testing a transformer of unknown condition, put a 4 ohm - 8 ohm power resistor in series with the (+) wire from your amplifier. The resistor will roll off the highs a bit, but it will let you know if the transformer is working or not without risking damage to your amplifier even if the transformer is internally shorted.
Radio Shack sells a 20Watt 8ohm resistor that would work nicely, Catalog #: 271-120
I reassembled the power supply and the crossover and hooked everything up.
They were louder but not 100% right. Additionally there was no sound from the woofer still. I switched the hookup to the bass terminals and the bass was there but all distorted. The jumpers are in place. I then switched back and the sound returned to the panel but then cut out.
Something isn't soldered in right or something. The FPO really did a job on these.
I'll try to do some sleuthing tomorrow after work.
Thanks
Eric
They were louder but not 100% right. Additionally there was no sound from the woofer still. I switched the hookup to the bass terminals and the bass was there but all distorted. The jumpers are in place. I then switched back and the sound returned to the panel but then cut out.
Something isn't soldered in right or something. The FPO really did a job on these.
I'll try to do some sleuthing tomorrow after work.
Thanks
Eric
Yes, that sounds about right.
They are even and that is great !!!
Try the woofers directly without the crossover at a low volume to determine if the drivers are good, If they are still distorting then I would say that they are blown or damaged.
It is good that you have the panels working now.
Sounds like you may have a bad switch as well.
Remember that there are two settings of the Bias voltage via switch on the bias supply and one setting will be lower than the other.
Yes check all of the solder connections, when they get heated like that the solder can get so hot that it will suck up into itself and cause an open or cracked connection to the board.
Steel rivets are known for this.
This happened to one of my monitors and my scope recently and resoldering them made them all good again.
Use a magnifying glass when examining the solder connections on the PCB's as some times they are very hard to detect with the naked eye.
Sound like you may also have a cracked trace maybe, as these are things to look for.
jer
They are even and that is great !!!
Try the woofers directly without the crossover at a low volume to determine if the drivers are good, If they are still distorting then I would say that they are blown or damaged.
It is good that you have the panels working now.
Sounds like you may have a bad switch as well.
Remember that there are two settings of the Bias voltage via switch on the bias supply and one setting will be lower than the other.
Yes check all of the solder connections, when they get heated like that the solder can get so hot that it will suck up into itself and cause an open or cracked connection to the board.
Steel rivets are known for this.
This happened to one of my monitors and my scope recently and resoldering them made them all good again.
Use a magnifying glass when examining the solder connections on the PCB's as some times they are very hard to detect with the naked eye.
Sound like you may also have a cracked trace maybe, as these are things to look for.
jer
Attachments
Oh I have cracked traces alright.
When they were damaged there was fire or at least smoke as there was soot on the caps of the power supply and inside the metal enclosure. The resin that covers the traces has been completely burned away below where the old resistors were. The PO ran beads of solder along the traces to mend the broken spots. I removes this as it was 1/8" thick and soldered in Teflon covered silver clad copper point to point.
What really sucks is I broke the glass tube from inside my solder sucker trying to get the huge globs of solder that had become lodged in side.
The woofers are fine. I hooked them up directly before and they are fine.
Seems there is an issue with the jumpers on the speaker terminals. This will also be part of my sleuthing.
Should I be trying to isolate the boards from the case or is the case grounded?
Thanks
Eric
When they were damaged there was fire or at least smoke as there was soot on the caps of the power supply and inside the metal enclosure. The resin that covers the traces has been completely burned away below where the old resistors were. The PO ran beads of solder along the traces to mend the broken spots. I removes this as it was 1/8" thick and soldered in Teflon covered silver clad copper point to point.
What really sucks is I broke the glass tube from inside my solder sucker trying to get the huge globs of solder that had become lodged in side.
The woofers are fine. I hooked them up directly before and they are fine.
Seems there is an issue with the jumpers on the speaker terminals. This will also be part of my sleuthing.
Should I be trying to isolate the boards from the case or is the case grounded?
Thanks
Eric
That I couldn't tell ya.
They could be using the case as a common ground connection.
Check and see if there are any traces going to any of the standoffs.
Sometimes cracks can form in the trace were the screw and washer compresses the board.
As badly as that board is burn't it could even be conducting causing a short!!
I had this happen on the power distribution board in my Mackie 32-8 mixer and it shorted half of the supply to all of the opamps causing it to go haywire and a dead master section.
It was enough to drop the voltage from +/-18V to below 12V or less on each rail.
A bypass cap went bad and shorted and the whole area was burn't with nothing left but charred carbon.
I could measure the resistance of the charred part with my VOM!
I had to grind out all of the bad material with my dremel like a dentist would do for a bad tooth before I could repair it.
Fixed it and all was good for 4 years until the last recent go around with the those crappy aging molex connectors that are in it.
jer
They could be using the case as a common ground connection.
Check and see if there are any traces going to any of the standoffs.
Sometimes cracks can form in the trace were the screw and washer compresses the board.
As badly as that board is burn't it could even be conducting causing a short!!
I had this happen on the power distribution board in my Mackie 32-8 mixer and it shorted half of the supply to all of the opamps causing it to go haywire and a dead master section.
It was enough to drop the voltage from +/-18V to below 12V or less on each rail.
A bypass cap went bad and shorted and the whole area was burn't with nothing left but charred carbon.
I could measure the resistance of the charred part with my VOM!
I had to grind out all of the bad material with my dremel like a dentist would do for a bad tooth before I could repair it.
Fixed it and all was good for 4 years until the last recent go around with the those crappy aging molex connectors that are in it.
jer
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The PO replaced every thing.
He had already burned everything up and then followed the upgrade using the Dayton caps that is posted on the internet.
He did a shitty job. He snipped a lot if the leads coming out if the PCBS and then snipped the cap and resistor leads and soldered the new parts to the stubs.
Ugggg!
Thanks
Eric
He had already burned everything up and then followed the upgrade using the Dayton caps that is posted on the internet.
He did a shitty job. He snipped a lot if the leads coming out if the PCBS and then snipped the cap and resistor leads and soldered the new parts to the stubs.
Ugggg!
Thanks
Eric
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