I blew my Hartke A35 up any guesses?

[Jsixis]

I have a Hartke A35 35 watts 10 inch speaker, like an idiot I took it to practice and tried to keep up with drums, anyhow the amp now buzzes bad, doesn't matter what speaker is hooked up to it.
Any ideal on what may be wrong? This amp is a PITA to work on.

 

[nigelwright7557]

Check output transistors first the n work back until all faulty components are replaced.
Also check impedance of your speaker in case the speaker blowing took your amp with it.

 

[JMFahey]

Here´s the schematic:

 

[Jsixis]

I took the amp out and did a quick test using the CD input, still buzzes so I put a thermometer on the 2 out put chips one was 90 degrees the other was 127 so it looks like I blew one of them.
Thanks

 

[Jsixis]

Thanks for the schematic, I was not able to find that on Hartke's site

 

[Bone]

Dont just change one transistor, you could have damaged the other, check both of them, and also check the drivers Q5 & 6 and the VAS Q4.

 

[wg_ski]

Q4 and Q5 are definitely at risk in this circuit if it is severely overdriven. Collector current of Q4 is not sufficiently limited. Looks like they’ve pulled out all the stops to maximize voltage swing on the VAS, even bootstrapping the entire + rail of the front end. Without a current limiter on Q4 it can feed a lot of base current into Q5.

 

[Jsixis]

thanks guys, not the easiest thing to work on. I'll need to clean up the bench area and need a couple of nasty weather days.

I'm pretty raw in this field, any clues as to what type of transistors as I have not found a parts list, I do have a large assortment of the smaller ones like Q4 & Q5 but the power transistors is what I am really looking for.