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Old 12th October 2006, 12:08 PM   #11
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Quote:
Originally posted by pborlace
TR8 tested and ok.

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Peter
Doesn't prove it will work when it has to work if you know what i mean.
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Old 12th October 2006, 12:14 PM   #12
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Take the good TR8 from the other channel and test again.
It's not much work and it save's money.
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Old 12th October 2006, 03:01 PM   #13
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I've just replaced TR8 with a new component. I'm getting the same voltage at FS1 and FS2 and FS2 blows.

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Peter
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Old 12th October 2006, 03:21 PM   #14
405man is offline 405man  Scotland
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I have had a faulty SOA circuit fail on several 405-2s These are shown as N1 & N2. These are mounted on 2 small 5 pin pcb/modules. To check you can remove these and the amplifier will operate with out them fitted but will not be protected against over current so do not connect a load to the output.

Stuart
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Old 12th October 2006, 03:27 PM   #15
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Now please stop blowing fuses, connect a light bulb accross F2, and switch on your amp.
See what is a voltage across collector - emitter of tr10, base - emitter of tr10, collector - emitter of tr8 and base - emitter of tr8.

Also, gentlemen who criticized Swinik, please show me your "Bridge" on the schematics. The whole patented "invention" is an approximation of a transfer function through the R38 resistor. It reminds me another patent, for the invention of the weapon with a screw-like trunk.
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Old 12th October 2006, 03:46 PM   #16
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Check also t2 on the small pcb board out the speaker teminals.
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Old 12th October 2006, 05:48 PM   #17
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TR10
b-e = 0.001v
c-e = 0.013v

TR8
b-e =0.015v
c-e = 0.013v
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Old 12th October 2006, 05:55 PM   #18
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Quote:
Originally posted by pborlace
TR10
b-e = 0.001v
c-e = 0.013v

TR8
b-e =0.015v
c-e = 0.013v
Did the current flow through the bulb connected instead of F2 fuse?

Now please check C16 and D11. Also, check if no odd connections between a minus rail and a ground.
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Old 12th October 2006, 06:05 PM   #19
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Current flowing through bulb.

Voltage at d11 = 0.016v
c16= 0.847v
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Old 12th October 2006, 06:09 PM   #20
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Quote:
Originally posted by pborlace
Current flowing through bulb.

Voltage at d11 = 0.016v
c16= 0.847v
I mean, check if they are alive and not shorted.

Unplug your amp, let it stay few minutes untill all capacitors are discharged, then check everything going from the F2 fuse, step by step, unsoldering and checking resistance to the ground with a speaker connected, probably D11 is bad, or emitter of tr10 is shorted to the heatsink.
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