Question about Amplifiers & Preamps
Current status: Amp goes in protection mode when switched on. On/Off light keeps blinking.
Problem: Left channel gave loud hum, the amp when in protection mode. Gave to service centre for repairs. Worked for few months and same problem came up. This time it burned left channel midrange B&W speaker that needed to be replaced. Service centre was of no help.
Request: I have adequate knowledge of electronics and if yor are able to guide me precisely, I may be able to repair the amp.
Thanks for help
After thorough cleaning of the speaker leads, PC Boards etc, I desoldered all the leads of the main two power transistors of the Left channel that had given problem earlier. Switched on the amp and bingo, it did not go in protection mode which confirmed that the two power transitors were the culprit. After checking the voltages and values of some other vital componenets vis-a-vis remaining left channels, it was confirmed that the circuitry was okay. The power transistors were checked again and found to be okay as well. I then took a chance and resoldered not only these two Left channel power trnasitors but also resoldered all the leads of all the other power transistors as well.
The amp was switched on again and this time also it did not go into protection mode. The amp is working fine. Problem could be either dry solder or short of power transistor leads by stray solder waste strand. There was no need to change any part which was great.
Thanks for help anyway.
Posted on Nov 30, 2008
The numbers of the transistors thay you need to replaced are on the transistor themselfs. Just take out the bad transistors and get the numbers that you need. I ALWAYS replace the output, driver and bias control transistor myself. One thing to keep in mind, if the number on the transistor starts with "A or B or C or D or K" you need to add "2S" in front of that number when you order it. Now that this problem has repeated itself, double check your wire and speaker. They can cause this problem.
Posted on Nov 12, 2008
Tips for a great answer:
Jan 18, 2016 | Denon Amplifiers & Preamps
Feb 18, 2014 | Amplifiers & Preamps
Dec 18, 2010 | Denon Amplifiers & Preamps
Nov 01, 2010 | Denon PMA-2000 IV R 2-Channel Amplifier
Oct 16, 2010 | Denon POA-8300 3-Channel Amplifier
Aug 21, 2010 | Cambridge Audio Azur 650a 2Channel...
Nov 03, 2009 | Denon Amplifiers & Preamps
Nov 04, 2008 | NAD C370 2-Channel Amplifier
Nov 01, 2008 | Amplifiers & Preamps
648 people viewed this question
Usually answered in minutes!