Gabbyhayes
New Member
A very interesting failure and repair!
The output transistors were blown..S/C
The driver transistor was ok.
The next transistor inline tested ok...sorta...after a closer look, which came with alot of head scratching was also faulty. As I said it sorta tested ok.
Lower gain, I missed that when I initially checked the transistor on my Heathkit IT-21.
When I checked again the gain was only about 15.
Under real world operation it would drive the transistors to saturation.
Output Q307 and Q308 were blown. Q306 was good. Q304 was faulty...low gain.
See Attached PDF
A very challenging repair.
The output transistors were blown..S/C
The driver transistor was ok.
The next transistor inline tested ok...sorta...after a closer look, which came with alot of head scratching was also faulty. As I said it sorta tested ok.
Lower gain, I missed that when I initially checked the transistor on my Heathkit IT-21.
When I checked again the gain was only about 15.
Under real world operation it would drive the transistors to saturation.
Output Q307 and Q308 were blown. Q306 was good. Q304 was faulty...low gain.
See Attached PDF
A very challenging repair.