20 Most Recent Alesis RA-150 Amplifier Questions & Answers

My Alesis SA-300 started the cutting out when at moderate levels some months ago... Well, Radio Shack has instant gratificaion for those who have one in the neighborhood. Part number 275-249 will do the trick!

I replaced the Dong Woo part with the Radio Shack item and the amp is back to its old self... maybe even a little better. Loud, clean and steady.

Thanks to all you who have contributed to this thread.


Alesis RA-150... | Answered on Jun 24, 2016

it may be an open input side coupling capacitor in the feedback circuit around the power amp. if the amp has a limiter in it it may be stuck. here is the service manual, in any case.


Alesis RA-150... | Answered on Dec 26, 2013

Start with the basics. Fuses, check transformer, look for burnt or damaged parts.
With this kind of thing more than one part could have failed. Indeed you could have more faulty parts than working ones! Or it could be just one thing that's gone!!!

Alesis RA-150... | Answered on Sep 02, 2013

Your first clue to going wrong with the repair is that the relay with two extra pins was the wrong type! So you need to look at the old one and read the ratings on it and search the net for one that does match it with the correct number of pins.
As for the resistors you need to read the colour code of them and again search for something the same size. The colour code will tell you the type you need. If you don't know how to read the colour code search on the net for a resistor colour code calculator.
As they look bad I would replace them, even if they did work, they could go dead later.

Alesis RA-150... | Answered on Jul 31, 2013

OK one thing at time first take cover off unit then check fuse if its blown there is a short do not replace fuse yet then locate bridge rectifier
check it for short if it is unsold-er and replace it then locate output transistors and check all of them for short. if one of the devices that i told you to check is bad then when you replace it then replace fuse and try powering up unit. be sure to replace all shorted parts before replacing fuse and powering it up. DE

Alesis RA-150... | Answered on Mar 29, 2013

Its samwha brand with a 100volt working voltage 6800 microfarad capacitance value its next symbols seems to me the chemical compositions or stock code, and its maximum working temperature. Could be a low ESR type capacitor.

Alesis RA-150... | Answered on May 09, 2011

The first things to check are the devices on the heatsink. They do all the work so tend to go when pushed! Remember stereo amps are just two amps put together, so at least you have a good channel (which is the same as the bad one) to do tests with say an ohmeter.

Alesis RA-150... | Answered on Apr 27, 2011

ALesis doesn't make it anymore and you can buy one for about $185 online.
If you could find the board , it would be about $75-125

Alesis RA-150... | Answered on Apr 06, 2011

Hi Cristina,
You may download the service manual of your unit at this LINK.

Alesis RA-150... | Answered on Mar 31, 2011

Check for a stereo/ mono switch in the front or back, and make sure it wasn't accidentally switched in the wrong position. Also check and make sure the wires are not crossing each other causing a short.

Alesis RA-150... | Answered on Feb 20, 2011

Either by sheer force or if you can see a hole in them, by an Allan Key.

Alesis RA-150... | Answered on Feb 06, 2011

Not finding what you are looking for?
Alesis RA-150 Amplifier Logo

36 questions posted

Ask a Question

Usually answered in minutes!

Top Alesis Audio Players & Recorders Experts


Level 3 Expert

5686 Answers

Ben Armstrong

Level 2 Expert

360 Answers


Level 3 Expert

904 Answers

Are you an Alesis Audio Player and Recorder Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

View Most Popular

Alesis Audio Players & Recorders

  • Alesis Audio Players & Recorders

Most Popular Question

samson power amp capacitor help

  • Audio Players & Recorders