Check the transistors marked 1A and 2A.
Re-check the output transistors in that channel to make sure none are leaky or shorted. Sometimes if they get to hot during replacement they can short or leak.
Once the DC is remedied if the channel will still not bias and has static check the diodes marked 5A and A7. Always check the smd resistors in the problem channel to make sure within tolerance.
Re-check the output transistors in that channel to make sure none are leaky or shorted. Sometimes if they get to hot during replacement they can short or leak.
Once the DC is remedied if the channel will still not bias and has static check the diodes marked 5A and A7. Always check the smd resistors in the problem channel to make sure within tolerance.
I run through them on diode test, and look for the .4-.6vdc on those transistors, I never been taught other wise. I just kind of figured bit out. Ididn't check the 5a diodes. I found a few resistors missing from this channel and the lm337 was completely ripped from the rail pad and all. Thinking maybe just cut out the section and mount mosfets to the, sink? No shorted outputs, I turned both bias peds all the way down. I'll change the drivers first. See what happens. Thanks sean
Sean what is the proper component for Q9, it was missing and I used a lm337? The other side has a lm317T
Changed alot of smd transistirs and now the DC offset is 5.9mv but still a square wave comes out on the scope on the right channel? Adjusting the bias pots changes it to square to triangle??
The lm337 is correct.
Are you saying when you inject a signal instead of a nice sine wave your getting a square wave?
So I been changing out the mmbt3904-06 transistors throughout the channels. And now the amp is cutting in and out. Drawing current then not, like trying to start over and over. Or in and out of protection?
Connect a load to the bad channel and drive a signal into it. Post an image of the waveform. Drive the output to about 2/3 of the way to the rail.
I can't get it to power up, the supply fluctuates from .8a to 1.50 to 2.3a over and over. I was going from 1.5 intially to 1.1 and staying on. And when I put a load on the left channel it draws current.
Post an image with no load.
You may need to post one with a load, but later. The transistors would have to heatsink compound and clamped down.
You may need to post one with a load, but later. The transistors would have to heatsink compound and clamped down.
It has the 39.5v back on the speaker terminal and I think the protection circuit is cutting it off and on. Scope just juspa around. This happened when I changed the password drivers. Q2,q1,q5,q4.
Something isn't right. It appears that the IC is driving the outputs but there is no output from the supply. What's the DC voltage across pins 1 and 3 for the power supply (password?) FETs
Yes and double checked them perry with the other side. This however before I found the bad driver transistor. I'll get some new numbers perry. Now it's back to driving them and I have gate signal at the power supply fets. I'll double check all my locations of the npn, and pnp's and recheck the 494 DC.
- Status
- Not open for further replies.