Martin Logan Montis Power Supply Board Help

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Key word is... work....in the end that the all we need...I guess...but like Tick did new better caps can give better sound...to any of these boards new are old..its a big upgread to get the old brown caps out of the board...or at lest the last two right before the 15mg res start.....
good luck... john I have never had a prob with logan....even this new guy... vary helpful
 
The new ML power supplies work the same way, just packed more tightly with cheaper parts.

Funny the more I think about your statement.....an your so right
But you ..our anyone relay when it come too ...what like
2k80-3k70 High Voltages...you think the older bias board type lay out ...would be the way to say for the best sound....just saying.......
but it works.....
 
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Finally had some time to get back to this -

- as far as the 5 pin connector, the PDF doesn't give any details on the pinout, but if it is like the SPIRE:
pin 1 will be +12Vdc
pin 2 will be ground
pin 3 will be -12Vdc
pin 4 will be ON/OFF control to power amp (same signal going to the LED connector)
pin 5 NC

You can cross-check by measuring continuity with the LM311 opamp pins.

LM311 pin 1 should be ground
LM311 pin 4 should be -12V
LM311 pin 8 should be +12V

Looks like pin 1 and 4 on LM311 are tied, so that means only single rail +12VDC voltage?

Also sent ML a schematic request for the BCFS7HVg power supply board
 
Looks like pin 1 and 4 on LM311 are tied, so that means only single rail +12VDC voltage? Also sent ML a schematic request for the BCFS7HVg power supply board

Hmmmm….yup, that means they are using the LM311 in single supply mode. Wonder why :scratch:
But, that doesn’t tell us if the supply pins are connected to (+12V and ground), or (+12 and -12V)…either combination could function as a single supply.

That would be great if ML can supply a schematic.
In the mean time, I outlined a few continuity tests below that will help identify if +12V/-12V are being used (or just +12V/ground), and which pins to hook the power to. See attached pic for identification of the various test points. Let me know what you find out, or if you have any questions.

Using DVM determine IC power connections to which Input connector pins (P1 thru P5):
LM311 Power Pins 4 & 8
- Ua4 has low resistance connection to pin Px?
- Ua8 has low resistance connection to pin Px?

LM324 Power Pins 4 & 11
- Ub4 has low resistance connection to pin Px?
- Ub11 has low resistance connection to pin Px?

Using DVM determine HV ground connections:
- Rc1 has low resistance connection to pin Px?
- confirm Rc2 has low resistance connection to HV1

Using DVM determine audio input ground connections:
- Terminal CON1 has low resistance connection to Ra1, Ra2, Rb1, or Rb2?
- Terminal CON2 has low resistance connection to Ra1, Ra2, Rb1, or Rb2?

The two remaining ends of Ra and Rb not having low resistance connection to CON1 or CON2
- should have low resistance connection to each other. Confirm.
- should have low resistance connection to Rc1 or Rc2? Determine which one.

====================================
By low resistance connection, I mean < 1 ohm.
By Px I mean which of the 5 input connector pins, P1 thru P5.
 

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Somehow got unsubscribed to my own thread...Thanks Bolserst

I will check all items this weekend!

Also confusing, I know these diaphragm bias supplies are supplied with +/- 12vdc from an ICEPower 200ASC module that powers the bass woofer. The -12vdc and ground being connected on the bias supply would short out the Icepower module....doesn't make sense...
 
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The -12vdc and ground being connected on the bias supply would short out the Icepower module....doesn't make sense...
Fortunately, having pin 1 connected to pin 4 on the LM311 will not cause a short between power and ground. The LM311 chip uses pin 1 as a reference for it's output stage. I made the (incorrect) assumption that pin 1 and pin 4 would be connected to different voltages since +/-12V are available for a split supply. Having the complete set of connectivity measurements from post#27 will tell us if pin 1 & 4 are both connected to -12V or to ground on the power input connector.
 
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OK, here we go Answers in RED

Using DVM determine IC power connections to which Input connector pins (P1 thru P5):
LM311 Power Pins 4 & 8
- Ua4 has low resistance connection to pin P3
- Ua8 has low resistance connection to pin P1

LM324 Power Pins 4 & 11
- Ub4 has low resistance connection to pin P1
- Ub11 has low resistance connection to pin P3

Using DVM determine HV ground connections:
- Rc1 has low resistance connection to pin P2
- confirm Rc2 has low resistance connection to HV1 - YES

Using DVM determine audio input ground connections:
- Terminal CON1 has low resistance connection to Rb1
- Terminal CON2 has low resistance connection to Ra1

The two remaining ends of Ra and Rb not having low resistance connection to CON1 or CON2 - YES - NEITHER
- has low resistance connection to each other. Confirm. YES, AND SHORTED TO HV1
- has low resistance connection to Rc2
 
Excellent!
Every test confirms that the power pins 1 thru 3 are arranged the same as the Spire.
Hook these up and apply an audio signal to CON1 & CON2 and you should be in business.
pin 1 = +12Vdc
pin 2 = ground
pin 3 = -12Vdc

You should not need to connect anything to pins 4 or 5.
For reference, the Spire had an ON/OFF control signal(ON=+12V, OFF=-12V) on pin 4 going back the the power amp module, and pin 5 for was not connected to anything.
 
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OK, great. Got it...

Also, this is what I see on other connections:

HV1 goes to the Step Up Transformer Center tap
HV2 (other side from HV1) is Bias Voltage to diaphragm
Spade Con1 is one side of step up tranny to Stator
Spade Con1 is other side of step up tranny to Stator

Correct?

And one more thing - what does switch do?
 
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All correct. (well, I'm assuming the 2nd Con1 was supposed to be Con2)

The small momentary switch discharges the the auto ON/OFF capacitor.
So, if you want to turn off the HV supply while testing or troubleshooting and don't want to wait 10-15minutes for it turn off by itself, just push the button.
 
Dear all, I had operated my Martin Logan Aerius 2 for several months, I drive these speakers with carver PM 900 , sound great untill one day the electro static section (hi and hid frequence) suddenly fade out whilst the sub still operates in normal condition. Is there any possibility of the failure in the electronic circuit board in the speaker causes this condition ? , is it possible that the excessive current from the power amp will break the circuit board ? (as i suspect the volume control in my old carver might erratically malfunction) . thanks for your help
 
Yes it is possible that failure in the power supply board could be the cause. Excessive current could have caused the limiter to fail, but this is pretty unusual. Let me know if you still need help solving this problem and I can provide some troubleshooting steps.

I know Indonesia is a large country, but I seem to recall that diyaudio member sumotan is also from Jakarta. I helped him solve a similar problem on his Odyssey speakers and he has become quite familiar with the Martin Logan power supply circuit. He may also be able to assist you.
ML Odyssey lower volume on 1 panel
 
Dear Bolrest,
it is an honor to get a response from this forum, thank you . Yes i still had this problem, I will gratefull, should you have time to give my your troubleshooting advise. Thanks also for your info on the similar case faced by Sumotan, I wil try to review the discussion on his case also. Again thank you and much appreciate
 
Usually the first step in diagnosing cases where one ESL is working and the other isn’t, is to remove the back and swap the HV power supply board between the two channels. If the problem follows the board over to the other ESL, you know the problem lies with the board. If the problem stays with the same ESL you know the problem is with the panel or wiring between board and panel. Since the ESL faded rather suddenly, I am pretty certain that the problem lies with the board, but best to run the swap test to make sure.

Once you have the backs off and can see the HV power supply boards, you can also run a couple other tests if the board swap indicates a bad board. Let us know what you find out.

1) Confirm that the red LED on the board comes on when the ESL is plugged in and music is being played
2) If LED on the board is lit, confirm that you are getting about 250VAC at the output of the HV transformer.

Attached is a copy of the schematic for the Aerius power supply board, along with locations to make the 250VAC measurement mentioned above if your board version is the MLPS-102. If it is a different version, post which one so we can identify where to make the measurements.
 

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