I have read everything on this amp, but after months and months of testing and repairing, I can not find the reason for a Neg 5 volt at the RH speaker out.
I have matched the transistors and tested and replaced anything that is even kinda out of spec.
The variable R119 resistor is turned all the way up to 5 ohms, no more adjustment.
If someone could be kind enough to point me to a proper test so I can get the amp finished.
I am using a Fluke 87 and a Heath 18 tester.
Thank You.
Dan.
I have matched the transistors and tested and replaced anything that is even kinda out of spec.
The variable R119 resistor is turned all the way up to 5 ohms, no more adjustment.
If someone could be kind enough to point me to a proper test so I can get the amp finished.
I am using a Fluke 87 and a Heath 18 tester.
Thank You.
Dan.
Thank you for clearing that up, I guess I was not understanding the circuit, I thought they went hand in hand.
I replaced ic101 with a LT1006, maybe I got it to hot when I installed it, I have a new op97e I can put in.
I will do that now and see what happens.
Thank you for the reply, Craig, I do appreciate it.
Dan....
I replaced ic101 with a LT1006, maybe I got it to hot when I installed it, I have a new op97e I can put in.
I will do that now and see what happens.
Thank you for the reply, Craig, I do appreciate it.
Dan....
I thought someone posted about the capacitors c157 c158 and c160, I just replaced those with a new op97, I used the variable resistors to set the bias at the t# posts.
I set it at the lower side of 3.5mv, I am still running the amp through a 72 watt bulb.
Now I have 8.1 volts of negative offset at the RH output.
I bought this amp from a audio store, it was a basket case, all apart, all transistors laying in a box, ALL of them. Half the resistors were missing. I have done my best to do this right, with the correct parts.
I sourced parts from bdent, Mouser and Digi key, I believe I recieved some fake or junk parts along the way. I replaced some parts 5 or six times with the same results. I have been on this since March.
I made another order from Bdent and replaced the already relaced transistors and low and behold I no longer have 80 volts, just the 8 volt neg on the RH side, LH is 0.00v.
Q101 and 102 I matched yesterday, and it made no difference.
At this point I am kinda at a stand still. There is something I am overlooking, I just do not know what that can be.
Dan.
I set it at the lower side of 3.5mv, I am still running the amp through a 72 watt bulb.
Now I have 8.1 volts of negative offset at the RH output.
I bought this amp from a audio store, it was a basket case, all apart, all transistors laying in a box, ALL of them. Half the resistors were missing. I have done my best to do this right, with the correct parts.
I sourced parts from bdent, Mouser and Digi key, I believe I recieved some fake or junk parts along the way. I replaced some parts 5 or six times with the same results. I have been on this since March.
I made another order from Bdent and replaced the already relaced transistors and low and behold I no longer have 80 volts, just the 8 volt neg on the RH side, LH is 0.00v.
Q101 and 102 I matched yesterday, and it made no difference.
At this point I am kinda at a stand still. There is something I am overlooking, I just do not know what that can be.
Dan.
Could anyone recommend a transistor tester that will load the transistor with working volts/amps. I have all kinds of parts that I can change out in a known good circuit, it seems as 90% are no good. My guess is the break down is way to low, or leakage, I do not know what to think any more.
Thanks.
Thanks.
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