Martin Logan Aerius i - New HT Board / Repair ? HELP !!

hi folks, looking for some help

I think I need a new HT board on one of a pair of Aerius i's as the panel is very quiet and if I move swap boards the fault moves with the board.

I have been quoted an eye watering £300 to replace the HT board in the UK :wtf:

Is there any other place I can buy new or refurbed parts ?
Is the HT board something that can be repaired without replacement ?
Any tips or links on a similar topic I could follow ?

Thanks in advance for your help !!!

Hola malcesine. Yes, it can be repaired, but you must have electronic and soldering a de-soldering skills. Inspect the foil side for a bad joint solder. Then, usually the problem is the transformer that it is located at the middle of the Power supply unit (PSU). You have to measure the AC voltage at the secondary winding. This secondary winding is facing the multiplier voltage, where you see diodes, capacitors. You can first measure the good one, and then the faulty. If the measure is OK, then check for a faulty diode at the multiplier. Also there are five 15M resistors that are connected in series to the end of the voltage multiplier to the red color cable that goes to the panel. This is the bias voltage. You need a special probe to measure it, because this voltage circa 2KV!. Usually one resistor is open. Pray for open 15M (resistor colors: brown-green-blue-gold ) If you want, PM to me with your email and also take a pic of the PSU with the components side. I will try to guide you better. Happy listening.

roberto said:

Hola malcesine. Yes, it can be repaired, but you must have electronic and soldering a de-soldering skills. Inspect the foil side for a bad joint solder. Then, usually the problem is the transformer that it is located at the middle of the Power supply unit (PSU). You have to measure the AC voltage at the secondary winding. This secondary winding is facing the multiplier voltage, where you see diodes, capacitors. You can first measure the good one, and then the faulty. If the measure is OK, then check for a faulty diode at the multiplier. Also there are five 15M resistors that are connected in series to the end of the voltage multiplier to the red color cable that goes to the panel. This is the bias voltage. You need a special probe to measure it, because this voltage circa 2KV!. Usually one resistor is open. Pray for open 15M (resistor colors: brown-green-blue-gold ) If you want, PM to me with your email and also take a pic of the PSU with the components side. I will try to guide you better. Happy listening.

Click to expand...

Roberto, you are a star !!!
I do have electronic experience, multimeter and soldering kit etc - I will start to follow your advised path and report back.....

pm also sent

roberto said:

Hola malcesine. Yes, it can be repaired, but you must have electronic and soldering a de-soldering skills. Inspect the foil side for a bad joint solder. Then, usually the problem is the transformer that it is located at the middle of the Power supply unit (PSU). You have to measure the AC voltage at the secondary winding. This secondary winding is facing the multiplier voltage, where you see diodes, capacitors. You can first measure the good one, and then the faulty. If the measure is OK, then check for a faulty diode at the multiplier. Also there are five 15M resistors that are connected in series to the end of the voltage multiplier to the red color cable that goes to the panel. This is the bias voltage. You need a special probe to measure it, because this voltage circa 2KV!. Usually one resistor is open. Pray for open 15M (resistor colors: brown-green-blue-gold ) If you want, PM to me with your email and also take a pic of the PSU with the components side. I will try to guide you better. Happy listening.

Click to expand...

That's great advice on checking the ML power supply boards.

Some of the guys over on the DIY audio site have modified their power supply boards on various ML speakers by increasing the amperage of the transformers, increasing the wattage of the 1/4-watt 15M-ohm high voltage output resistors to 3w or 5-watts and increasing the DC voltage power output from 3Kv to 3.5Kv or 3.8Kv. You will also find a pdf schematic for the ML bias power supply board which may be very useful when checking all your components. http://www.diyaudio.com/forums/planars-exotics/200227-martinlogan-bias-mod-2.html

Thanks again for the feedback roberto and #ZERO

My board I think is a newer version of the one above, its is MLPS-103 rev h and it doesn't have a fuse

The 15M resistors are all good but I think I have an open circuit winding on the transformer
The Part No is 60T2706 but I can't find one anywhere despite trawling google for ages.
Any tips of finding one or an equivalent ?

thanks

I would contact Scott Gribble at ML and you should be able to purchase a replacement transformer for sixteen bucks plus shipping cost.

#ZERO said:

I would contact Scott Gribble at ML and you should be able to purchase a replacement transformer for sixteen bucks plus shipping cost.

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Have contacted ML who have given me the UK agent details and they are the same supplier that quote £300 for one HT board.
I have contacted them and hopefully they can supply the part rather than the whole board.

Will report back on progress.

#ZERO said:

I would contact Scott Gribble at ML and you should be able to purchase a replacement transformer for sixteen bucks plus shipping cost.

Click to expand...

I was able to order this transformer separately from ML (I spoke w Dana Brown) last year for $16 + shipping, so you may be able to get it straight from ML in USA?

Tosh said:

I was able to order this transformer separately from ML (I spoke w Dana Brown) last year for $16 + shipping, so you may be able to get it straight from ML in USA?

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Thanks for the tip Tosh, looks like ML UK won't help at component level (but they will sell me the whole board at $480 !!)
ML USA can't supply to the UK due to international dealership rules etc so I need to find some kindly person in the US to order and ship to me !!

Unless of course there is an equivalent of the transformer that is commonly available ?

The transformers were manufactured by Coil-Tran Corp part number: 60T2706 EIA696B1-9717 OBJY2 which were custom made to ML specifications. I tried contacting the supplier which is now Hobart Electronics to see if they could supply me a PCB mount transformer with a slightly higher amperage rating but they won't release any information or custom maunfacture transformers on a small quantity order basis. So the only alternative would be to have someone here in the US to order them from ML and have them shipped to the UK.

Hola. I would like to help, but my parts are 120V, not 220-240V as UK. If someone is going to help this friend, keep in mind that the transformer must be 220-240V. Happy listening!

roberto said:

Hola. I would like to help, but my parts are 120V, not 220-240V as UK. If someone is going to help this friend, keep in mind that the transformer must be 220-240V. Happy listening!

Click to expand...

I believe the transformers are the same for each voltage because they have dual primaries & dual secondary windings. http://www.hobart-electronics.com/transformers/global_5h.html

I'm also pretty sure it the A & B jumper locations on the PCB which determine the voltage settings.

Hola. #ZERO. I just realize that you are right. There are specific power supplies for 50Hz, ( and I was assuming this) that will not work with 60Hz, and it is the frequency line that will not turn on the PSU, not the voltage. What you are saying is right. The transformer comes with two primary windings, and it is connected in parallel for 120V, and in series for 220V. The Aerius is not this case, and the transformer will work for both voltages. I made a mistake! Thanks for the tip, #ZERO. Happy listening!

hi #zero,

Is the board in the pic from an aerius i ? or from a standard aerius ?
Reason I ask is that I might be able to get a pair of MLPS-102 boards in the UK

thanks

#ZERO said:

That's great advice on checking the ML power supply boards.

Some of the guys over on the DIY audio site have modified their power supply boards on various ML speakers by increasing the amperage of the transformers, increasing the wattage of the 1/4-watt 15M-ohm high voltage output resistors to 3w or 5-watts and increasing the DC voltage power output from 3Kv to 3.5Kv or 3.8Kv. You will also find a pdf schematic for the ML bias power supply board which may be very useful when checking all your components. http://www.diyaudio.com/forums/planars-exotics/200227-martinlogan-bias-mod-2.html

Click to expand...

malcesine said:

hi #zero,

Is the board in the pic from an aerius i ? or from a standard aerius ?
Reason I ask is that I might be able to get a pair of MLPS-102 boards in the UK

thanks

Click to expand...

Power board for the ML Aries: http://www.canuckaudiomart.com/details/649010555-martin_logan_cross_over

If you have the MLPS-103 rev h power board without the PCB fuse installed; I would keep that version since it's used in many of the larger ESL panels, such as the Monolith-III, CLS-II, ReQuest and quite a few others. Also they both have the same transformer and use similar A & B jumper locations for the different voltage options.

Thanks again for everyones help :cheers:

I have a pair of HT boards harvested from old Aerius's in the UK coming soon

Hopefully that will do the trick either by a) robbing the transformer from one to fit to mine or 2) replacing both boards if I have too

UPDATE:

Now have an older MLPS-102 from the Aerius and have connected it in place of the MLPS103 rev h on my Aerius i

Problem is the connections to the X-OVER transformer are not the same on both.
On the 103 there are 4 wires to 4 different PCB terminals, on the 102 there are only 2 wires and only 2 terminals to connect to.

On the 103 3 of the 4 are actually connected together via PCB track and are not connected to anything else on the PCB and the other is connected to a series of 15Mohm resistors.
On the 102 one wire also connects to the 15M resistors but the other is connected via a 15M resistor and then ground.

My first instinct was to simply connect all 3 wires from the 103 together into the one terminal that goes to the 15M resistor then ground but I am worried I might damage the board.
Alternatively I can remove the 15M resistor in question to isolate from ground.

The other difference is that the mains power has ground wire on the 102 but not on my 103.

Kinda looks like a difference in grounding overall, with the 103 optional resistors not used.

Any initial thoughts ?

It seems as if you have everything hooked up correctly from the picture above. Just make sure the high voltage positive red wire located near the four 15M-ohm resistors side is going to the ESL panel and the other red negative wire on the opposite side is going to the stator transformer. Don't worry about the extra green ground wire on the power cable side as it's only the white & black wires that supply the transformer with the 230 voltage. The other two pin connector in spot BB4 on your original board is not used so there's no need to worry it not having it on the older version board.

#ZERO said:

It seems as if you have everything hooked up correctly from the picture above. Just make sure the high voltage positive red wire located near the four 15M-ohm resistors side is going to the ESL panel and the other red negative wire on the opposite side is going to the stator transformer. Don't worry about the extra green ground wire on the power cable side as it's only the white & black wires that supply the transformer with the 230 voltage. The other two pin connector in spot BB4 on your original board is not used so there's no need to worry it not having it on the older version board.

Click to expand...

Thanks #ZERO, got similar feedback from ML so will connect up and test tomorrow and report back

Quick Update...

New board fitted and wired as per posts here and everything now works superbly well !
Very happy and thanks to everyone for the great advice... :->