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Acurus A150

K

koryrf

New Member
My recently purchased Acurus A150 has an issue. It appears that one of the channels is failing to transmit lower frees (sub 200 hz) to the speakers. Lots of troubleshooting has isolated the issue to one channel in the amp (swapping speakers, swapping preamps, swapping cables... etc.).

While I am handy and I own a decent LCR meter and soldering station, I am not a small electronics repairman. Still, I'd rather fix it myself if it is something relatively simple. Any ideas or advice? TIA.
 
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Hi Kory:

Welcome to AudioKarma!

I'm sorry you are facing an issue with the A-150. Acurus amplifiers are very well designed & built (proudly in the USA) and are still sought after by audiophiles as they perform even better with select upgrades.

Given the fact that this unit is 25+ years old and has both channels working, the reduction in lower frequencies on one channel could be attributed to the dried up capacitor at the input stage. I would suggest replacing the 10uF bipolar capacitor C1 at the input with a audio grade Nichicon or Elna. You could also replace the 0.1uf bypass capacitor C2 with a Wima MKP film. Refer to this thread for details on this including a "cleaner" schematic, thanks to the efforts of @mondialfan.

https://audiokarma.org/forums/index.php?threads/restoring-an-acūrus-a150-soliciting-advice.858960/

In addition, there are several well documented upgrade/restoration threads on AK and DIYAudio should you decide to go that route once you have this issue taken care of.

Keep us posted on your progress.

Best Rgds,
Mayank
 
Mayank said:
Hi Kory:

Welcome to AudioKarma!

I'm sorry you are facing an issue with the A-150. Acurus amplifiers are very well designed & built (proudly in the USA) and are still sought after by audiophiles as they perform even better with select upgrades.

Given the fact that this unit is 25+ years old and has both channels working, the reduction in lower frequencies on one channel could be attributed to the dried up capacitor at the input stage. I would suggest replacing the 10uF bipolar capacitor C1 at the input with a audio grade Nichicon or Elna. You could also replace the 0.1uf bypass capacitor C2 with a Wima MKP film. Refer to this thread for details on this including a "cleaner" schematic, thanks to the efforts of @mondialfan.

https://audiokarma.org/forums/index.php?threads/restoring-an-acūrus-a150-soliciting-advice.858960/

In addition, there are several well documented upgrade/restoration threads on AK and DIYAudio should you decide to go that route once you have this issue taken care of.

Keep us posted on your progress.

Best Rgds,
Mayank
Click to expand...

Thanks Mayank! I assume I should replace the caps you mention on both channels to keep everything balanced right?
 
Mayank said:
Hi Kory:

Welcome to AudioKarma!

I'm sorry you are facing an issue with the A-150. Acurus amplifiers are very well designed & built (proudly in the USA) and are still sought after by audiophiles as they perform even better with select upgrades.

Given the fact that this unit is 25+ years old and has both channels working, the reduction in lower frequencies on one channel could be attributed to the dried up capacitor at the input stage. I would suggest replacing the 10uF bipolar capacitor C1 at the input with a audio grade Nichicon or Elna. You could also replace the 0.1uf bypass capacitor C2 with a Wima MKP film. Refer to this thread for details on this including a "cleaner" schematic, thanks to the efforts of @mondialfan.

https://audiokarma.org/forums/index.php?threads/restoring-an-acūrus-a150-soliciting-advice.858960/

In addition, there are several well documented upgrade/restoration threads on AK and DIYAudio should you decide to go that route once you have this issue taken care of.

Keep us posted on your progress.

Best Rgds,
Mayank
Click to expand...
May I pose a question please.I bought a 150 untested although buyer claimed it worked.With headphones I can hear this slight ticking in one channel.Upon connecting speakers those slight tickings became loud pops.I just shut it down.The only "repairman" in town said output transistors and gave a $500 estimate which I was very skeptical of.Was I wrong in my skepticism?
 
koryrf said:
My recently purchased Acurus A150 has an issue. It appears that one of the channels is failing to transmit lower frees (sub 200 hz) to the speakers. Lots of troubleshooting has isolated the issue to one channel in the amp (swapping speakers, swapping preamps, swapping cables... etc.).

While I am handy and I own a decent LCR meter and soldering station, I am not a small electronics repairman. Still, I'd rather fix it myself if it is something relatively simple. Any ideas or advice? TIA.
Click to expand...


Hello Kory,

You should replace the 220uF electrolytic caps on the channel boards. These are bipolar caps, they are located in the feedback loop and if they dry out over time they will cause a loss of low freq. Once you get down below about 50uF in these caps you'll begin to notice the loss of bass.
 
:thumbsup:
KC (@mondialfan) is the resident Aragon & Acurus guru with invaluable experience and is very generous with his support to fellow AK-ers !!

Affirmative, replace the capacitors in both channels - the unit should be good for the next 20+ years. I have had good experience with Nichicon UES "Muse" series bipolar electrolytic capacitors, they are around ~$1 each on Mouser.

Good luck
Mayank
 
Thanks all. Right now I am starting think it may not be the amp at all. I thought I solidly troubleshot it down to the amp, but today found that my preamp appears to be dodgy. It's a PS Audio 6.0 and the company says it's to old to fix (the won't do it and they said the parts were too expensive). For now, I need t get my paws on a new preamp to chase the gremlins down.
 
Koryrf

I've seen a lot of those old PS Audio pre's with problems for sale on the big auction site over the years. I've thought about buying one of them a few times to dabble with but it always seems that I have too many projects going on.
 
superdog said:
May I pose a question please.I bought a 150 untested although buyer claimed it worked.With headphones I can hear this slight ticking in one channel.Upon connecting speakers those slight tickings became loud pops.I just shut it down.The only "repairman" in town said output transistors and gave a $500 estimate which I was very skeptical of.Was I wrong in my skepticism?
Click to expand...


At first that seems like a quite high price, but its a lot of work especially if there's other parts that are bad. I could see a good tech spending a full day on it if additional problems were there.

However,
I'd be hard pressed to spend that kind of $$$ for repair especially when you can pick up another A150 for about half that cost and then you'd have two replacement channels.
 
mondialfan said:
At first that seems like a quite high price, but its a lot of work especially if there's other parts that are bad. I could see a good tech spending a full day on it if additional problems were there.

However,
I'd be hard pressed to spend that kind of $$$ for repair especially when you can pick up another A150 for about half that cost and then you'd have two replacement channels.
Click to expand...
Thanks.I felt the same way.Im just going to cut my loses with this and perhaps ebay it as parts unit.
 
I currently have a A150 that was serviced and looks to be main filter caps replaced as well as the ones in the signal path. I’m using a Nikko Beta 20 preamp with it and driving a set of A/D/S 570/2 speakers. Excellent sound and really wakes up and speaker I’ve put on it.
 
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