Alesis RA150 burns power resistor - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 11th January 2014, 11:35 AM   #1
diyAudio Member
 
Join Date: Jan 2014
Default Alesis RA150 burns power resistor

Hi All,

I am new to audio electronics tinkering and hope my diyAudio participation proves valuable to others as well.
Jumping right in: My recently repaired Alesis RA150 worked for 2 wks then quit, again burning out the power resistor.
What happened: Heard a “click” thru spks, volume increased on its own, “searing” noise thru spks, sound died amid smoke.
What I found: 1. Mains Fuse burned; 2. R401 (470/2W) burned; 3. C403 (220uf) bulging at top but testing normal with analog vom; 4. Z1 (15V) shorted.
Repair Status: Changed those 4 parts and reconnected LED indicator circuit, Driver amps and Pwr amps to Pwr Supply board one at a time.
Bench running at low volume for a couple hours now. DC at spk terminals: Rt – 0.1mV Lt – 0.5mV
Question: What else should I check and/or replace before putting amp back in service? Previous fix included change of all el’tic caps except main filters and 2 in the LED circuit. Schematics can be viewed here http://forum.vegalab.ru/attachment.p...mentid=75690&d
Big thanks.
Mort
  Reply With Quote
Old 18th January 2014, 11:59 AM   #2
diyAudio Member
 
Join Date: Jan 2014
Default Update to Alesis ra150 burns resistor

Update on Alesis RA150:
Bench run unit for 6-10 hrs daily since replacing 470R and zener.
Rigged 12 volt fan above area of PS board and ran unit thru Polk LSI9s for 2 hrs with enough volume to fill my ~ 24x24 room. No problems (Right ch slightly lower volume than Left).
Next project is a Kenwood KR-2090 Receiver with crackly controls and a misfiring phono stage. CD input to Aux gives no discernable distortion. Anyone with a schematic?
Thanks.
Mort
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Schematic for Alesis RA-100... Ha! Alesis doesn't have it!! crispycircuit Solid State 0 22nd February 2010 09:16 PM
lm4780 Zobal resistor burns immediately on Power ON kuldeepsingh Chip Amps 22 2nd August 2008 12:43 AM
Alesis RA500 Power Amps x2 Tenson Swap Meet 3 2nd February 2008 10:28 PM
Philips cd880 player channel dead, resistor burns out canuck Digital Source 1 2nd September 2004 10:38 PM
Alesis ADAT Power supply TTLHARMNIKDSTN Digital Source 0 10th June 2004 02:04 AM


New To Site? Need Help?

All times are GMT. The time now is 10:43 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2