Luxman R-1070 Output Transistor Subs
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Better? Maybe not better, but electrically suitable even though mounting may require modifications:
2SD745 ==> MJL3281A
2SB705 ==> MJL1302A
I had 2SB784A/2DS736As fail in a Kenwood and refit the OnSemi devices cleanly.
Since DigiKey evidently has the correct package devices, that makes it a lot easier, even though they are twice the cost.
2SD745 ==> MJL3281A
2SB705 ==> MJL1302A
I had 2SB784A/2DS736As fail in a Kenwood and refit the OnSemi devices cleanly.
Since DigiKey evidently has the correct package devices, that makes it a lot easier, even though they are twice the cost.
Except the Darlington part numbers.
I finally got the time to install the caps and transistors for the Luxman 1070. Was getting ready to install the output transistors and found i was short 2 insulators. While i am waiting for the insulators to arrive i was wondering if i could fire up the receiver without the outputs and test voltage.
Found a post by AKer JURB
"Most amps have low value resistors from the emitter to base. Reading low from collector to either means it is bad. If it is reading a short collector to emitter in circuit then the drivers transistors are suspect.
Leave the outputs clean out and fire it up and take voltages. If you read low B-E and the rest of the amp is OK you should get low offset and no drop across the emitter resistors. Do not connect speakers at this time, though you might try some headphones.
If that works, measure the voltage between the positive and negative driver transistor's bases, they should be approximately the same."
My receiver had 3 of the 4 output transistors blown. Before I install the output transistors I was wondering if I could test voltages to them.
Negative probe to chassis and positive probe to one of the transistor leads from the board?
Is there any other tips to doing this or just turn on the receiver and be careful not to short anything while testing?
Thanks,
Monte
Thanks,
Monte
Found a post by AKer JURB
"Most amps have low value resistors from the emitter to base. Reading low from collector to either means it is bad. If it is reading a short collector to emitter in circuit then the drivers transistors are suspect.
Leave the outputs clean out and fire it up and take voltages. If you read low B-E and the rest of the amp is OK you should get low offset and no drop across the emitter resistors. Do not connect speakers at this time, though you might try some headphones.
If that works, measure the voltage between the positive and negative driver transistor's bases, they should be approximately the same."
My receiver had 3 of the 4 output transistors blown. Before I install the output transistors I was wondering if I could test voltages to them.
Negative probe to chassis and positive probe to one of the transistor leads from the board?
Is there any other tips to doing this or just turn on the receiver and be careful not to short anything while testing?
Thanks,
Monte
Thanks,
Monte
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