Orion 4100GX - right channel out

[mitchyz250f]

I've marked x's on the packages that get hot.

[Perry Babin]

There are 3 outputs grouped together but only one has an x on it. Remove it and clean the pads to ensure that there are no solder bridges. Does that change anything?

[mitchyz250f]

I don't understand what you mean with the 3 outputs. It seems like the output(yellow wire) is connected to a group of 6 TO-220 packages(top left of picture). Can you further describe which package you are talking abot?

[Perry Babin]

There is a group of 6 outputs for one channel. There are two groups of 3 for that channel. One group of 3 had 3 Xs. The other group of 3 has 1 X. Remove the transistor with the X in that group of 3.

[mitchyz250f]

That does seem to be the issue. Before removing the component I measured resistance to be ~200 ohms between pins 2 and 3. After removing it went up to Mohms.

I'm looking to find out what the part number is. The numbers are not legible, but it looks like 2N6438. I can only find that part as a TO-3, so it doesn't look like I'm able to read the part number well enough. How can I go about finding the part number, or selecting an appropriate alternate?

[Perry Babin]

2N6488. They have to be replaced in groups.

[mitchyz250f]

Thank you Perry. By the way I did go ahead an turn on the amp(no load) to ensure the short was fixed and both channels now draw standby current of ~.8A.
I'll go ahead and replace all 6. Should I also be replacing the complementary 2N6490s or is it only important to change the ones in parallel with each other?

[Perry Babin]

If you want the amp to be as reliable as possible, replace the 2N6491s also.

[mitchyz250f]

Great. Thank you again Perry, you've been a huge help.
I'll confirm all is well once I get these components in and test the amp.

[mitchyz250f]

I tested the amp and after about 15 seconds on I heard a noise and smelled some smoke. I turned it off quickly, but now when I turn it on it draws ~15A (current limited on my power supply).

I am trying to trace the problem and I've found that there is no voltage on one of the inputs to the transformer, so I suppose it's the drive circuitry, but I am unsure how this amp is laid out. What components should I be look at or what tests should I perform?