Ok, so I know that this Sunn's output transistors are getting too hot. What I'm sensing is it seems hottest around Q3. I've tried diaging it by following some other posts people have on the forum and it seems that I may have some resistor issues for Q5 and Q2. I've checked the windings on the trans and all the secondary coils are around 2.7 ohms and the primary is 18ohms. Checking the ohmage of B-E in circuit on the transistors is showing:
Q5-42
Q4-25.6
Q3-26.3
Q2-40
Voltages are as follows:
Q5= (E) -1.26 (B) -.66 (C) 17.44
Q4= (E) 17.9 (B) 18 (C) 46
Q3= (E) .3 (B) .84 (C) 46
Q2= (E) -1.2 (B) -1.3 (C) -.005
Q1= (E) 1.9 (B) 2.4 (C) 37.5
These are all with no load on the speaker jack. Which, by the way, has 17.8vdc on it.
Any suggestions on where to go next? There has been considerable work done in the past from what I see. New caps and wires soldered on where the quick connects broke off of them.
sunn_concertbass2.pdf
Q5-42
Q4-25.6
Q3-26.3
Q2-40
Voltages are as follows:
Q5= (E) -1.26 (B) -.66 (C) 17.44
Q4= (E) 17.9 (B) 18 (C) 46
Q3= (E) .3 (B) .84 (C) 46
Q2= (E) -1.2 (B) -1.3 (C) -.005
Q1= (E) 1.9 (B) 2.4 (C) 37.5
These are all with no load on the speaker jack. Which, by the way, has 17.8vdc on it.
Any suggestions on where to go next? There has been considerable work done in the past from what I see. New caps and wires soldered on where the quick connects broke off of them.
sunn_concertbass2.pdf
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