Ascent power supply board failed - replace or repair/tweak?

[Tom33731]

The power supply board in my Ascent speaker just failed.

I am considering several options:

1) I can simply swap out for a new power supply board from Martin Logan ($379).

2) Since it has discrete components, I can have the existing board repaired

3) Have the new or existing power supply board modded with new and better components.

4) Have the crossover modded with new and better components.

Any thoughts or recommendations?

 

[Robert D]

Choosing between option 1 and 2 should be easy. If the new ones only cost $379, it doesn't make any sense repairing the old.

My Prodigies were made in 2000. I sure hope my power supplies don't go out. How common is that, does anybody know? It's awesome that ML still makes those for us.

 

[Brandon Hartwick]

The answer to your question depends on what's wrong with the board and if you have the skills or know people that could do the repairs.

$380 isn't terrible, but if it's something really simple I'd attempt to repair them for sure.

 

[Tom33731]

Thank you Robert and Brandon.

@ Robert - "it doesn't make any sense repairing the old." - that is my thought as well, because there may be other components ready to fail, or design improvements.

@ Brandon - " I'd attempt to repair" - that is an option as well, there is a good service person in my locale.

I will wait to see if there are further posts before making a decision.

 

[Tom33731]

Does anyone have any insight into whether the power supply board (when properly functioning) has any impact upon sound quality?

 

[Robert D]

Does anyone have any insight into whether the power supply board (when properly functioning) has any impact upon sound quality?

Good question. Is there a way to upgrade that as well? I'm guessing no.

 

[Brandon Hartwick]

Good question. Is there a way to upgrade that as well? I'm guessing no.

I believe all the power supply section does is supply the ESL panel with an electric charge. If everything is operating as it should I don't see how it would effect sound. I've heard about the transformer possibly having an effect on sound but that's opening a can of worms.

 

[Tom33731]

I believe all the power supply section does is supply the ESL panel with an electric charge. If everything is operating as it should I don't see how it would effect sound.

I ordered a new power supply for the one speaker. After installation, I will compare the two speakers and let you know if I perceive any audible difference.

 

[Peter Ward]

I have Ascents so will be very interested in you results.

 

[jaffrie]

Hi Guys,
There will be a difference in sound if the bias voltage is higher or lower then the other speaker.
There's a couple of resistors on the board that can make changes to the voltage

 

[Leporello]

The answer to your question depends on what's wrong with the board and if you have the skills or know people that could do the repairs.

$380 isn't terrible, but if it's something really simple I'd attempt to repair them for sure.

As an experienced tech that would be my choice. Spend a few hours or minutes seeing if it's a simple problem and if it's simple to repair. As long as you're sure it isn't the tranny, which indeed would be a can of worms. I would give myself one day to solve it, then bite the bullet. Time and aggravation are worth more than $380.

The transformer should be putting out a few hundred volts all the time, easily and relatively safely verifiable with a multimeter (preferably, clip on test leads before energizing and keep your hands free). The board consists of an op amp based audio signal presence detector, a triac that switches between high and standby voltage and a voltage multiplier stack of multiple rectifiers and capacitors (the most likely failure point). A schematic may be available somewhere. A high voltage probe and good safety procedures are a must (keep one hand away from anything, discharge before touching again, etc.). An accident with the bias supply probably won't kill you but those aren't dice I would roll. If you are unsure about any of this just get the board.

As for performance enhancing mods, you would obviously need to do them to both speakers. I would pass until I had them both working to original specs.

 

[Tom33731]

Hi Guys,
There will be a difference in sound if the bias voltage is higher or lower then the other speaker.
There's a couple of resistors on the board that can make changes to the voltage

Good observation! I ordered a replacement power supply board from ML, and installed it. The speaker now works, but is about 1 dB lower in volume that the other speaker. I have adjusted (via my AV processor) the volume to match.
So all is working well.

 

[Tom33731]

Thank you all for your helpful posts. I really appreciate your insights.
I did order a replacement power supply board from ML, and installed it. The speaker now works well. Once the volume was adjusted (see above), the repaired speaker sounds the same as its mate.

 

[Tom33731]

BTW, ML support did suggest:
>> these are old panels and should be replaced in the near future.

 

[Leporello]

If the new ones only cost $379, it doesn't make any sense repairing the old.

If it's not something obvious you can find yourself (such as replacing charred components), agreed. Not much to it, though: a voltage multiplier stack (diodes, capacitors) and signal detection/turn on circuit. Does the LED light up when you feed the speaker a signal? If it's the power transformer, though, replacing the board won't help. A high voltage probe would be useful, and used ones are cheap now that few people are repairing CRT displays.

Personally, I'd spend an hour or so trying to troubleshoot the board, then order the replacement, assuming I'd verified the transformer is OK.

 

[Leporello]

If it's not something obvious you can find yourself (such as replacing charred components), agreed. Not much to it, though: a voltage multiplier stack (diodes, capacitors) and signal detection/turn on circuit. Does the LED light up when you feed the speaker a signal? If it's the power transformer, though, replacing the board won't help. A high voltage probe would be useful, and used ones are cheap now that few people are repairing CRT displays.

Personally, I'd spend an hour or so trying to troubleshoot the board, then order the replacement, assuming I'd verified the transformer is OK.

Just realized I replied to the post a while ago and you have it working. Never Mind.