Hello all...I have had a DA4ES for about 5 years now and have always loved the unit. I recently upgraded to a new TV, so I had to reconfigure my receiver cabling, move its' position, etc.
Upon hooking everything back together, I noticed the my front left speaker channel wasn't producing any sound unless I crank the volume WAY up (like to 10 db or so...). Once I get it to produce sound, I can then lower the volume to a normal level, but I have to do this every time I turn the receiver on these days.
The speaker connection is fine, but I must have fried some resistor when I moved the unit.
Anyone have any ideas of what might be the culprit? Is there an easy fix/ part to replace that I can DIY? I have a decent repair technician in town I can send the unit to, but I am hoping I might be able to fix it myself.
Joined: Mar 13, 2003
Posts: 13788
From: Sewell, NJ
Posted: 2009-11-15 18:39
Welcome to Agorquest! You probably blew a left channel output transistor, which usually takes out a resistor that acts like a fuse. The left channel output transistors are IC 502 and IC503. Check R526 in the vicinity of the output transistors. If the value is >> 33 ohms, one of the two transistors is shorted and must be replaced as well as the resistor. Also check R524 and R525. If the value of either is >> 10 ohms, the resistor needs to be replaced. Its a good thing that these resistors are in the circuit as they mitigate the consequences of a shorted output transistor.
Wow, jehill. Seems that are pretty familiar with this stuff. You always amaze me with your know how. I sure hope I never need your help in this way, but very thankful to know that you're there for us.
Curious though, rather than use resistors as fuse, why not use a fuse? It would be easier to replace, right.
DenMar
Joined: Mar 13, 2003
Posts: 13788
From: Sewell, NJ
Posted: 2009-11-18 19:58
The advantage of using resistors is that you can determining the current through the resistor by measuring the voltage drop across it and then applying ohm's law (I = E/R). I looked at the schematic closer and see that the 33 ohm resistors are not identified as protective resistors. Instead, they determine the bias applied to an output transistor pair.
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Posted: 2009-11-15 01:09
Posted: 2009-11-15 18:39
