Transistor circuit help needed

[John482]

I have an amp on my vintage Telefunken r2r that has lost one channel due to shorted output transistor. I was checking it out and noticed that I have portion of the circuit showing 6.7k across a 6.7k resistor, the functioning channel shows about 800 ohms across it's 6.7k resistor. Both resistors out of circuit show 6.7k. Ideas?

 

[J!m]

You have all the test point voltages- check all of those to help narrow the search.

 

[John482]

You have all the test point voltages- check all of those to help narrow the search.

Nope, it's blowing fuse. Sorry should have said.

 

[Gepetto]

I have an amp on my vintage Telefunken r2r that has lost one channel due to shorted output transistor. I was checking it out and noticed that I have portion of the circuit showing 6.7k across a 6.7k resistor, the functioning channel shows about 800 ohms across it's 6.7k resistor. Both resistors out of circuit show 6.7k. Ideas?

It appears that each resistor is spanned by the B-E junction of T302 or T402 depending on the channel. That B-E junction could be what is measuring 800 ohms on the good channel. Since the B-E junction is polarity sensitive, have you measured the resistor, in circuit, using both polarity directions of your DMM?

 

[John482]

The good channel resistor is the one at 6.8k, r306 is measuring 800 ohms. I stated that wrong, sorry. R406 in the good amp is 6.8k. I measured both out of circuit and both resistors are spot on.