I am a novice in spite of quite a few years of success and failures. I do not have a strategy or procedure to follow. I have just bounced aroun looking for a problem. I have a Bryston 3B on my bench. I have checked with Dim light bulb and have now plugged it in and turned it on. It was handed to me and I was told nothing except that it doesn't work.
What are my next steps. I believe myself that I should check for DC offset so that I don't cook my test speaker. Is this correct? Then what?
What are my next steps. I believe myself that I should check for DC offset so that I don't cook my test speaker. Is this correct? Then what?
Murphy's law. The one time I decide that I am going to do the job right, I find a lead from the transformer secondaries disconnected. I plugged it in, tested the amp, called the owner of the Amp. Asked him what was wrong with the amplifier. "Dead on one channel" he says. I went back to the amp. The disconnected lead corresponded to the dead channel.
Hi Guys
Bryston offers fantastic service support, so there is no reason for most techs to even bother.
In general, 99% of amps are tested and repaired without a load and definitely without a speaker. You eventually get to connecting a light bench load, then a heavy one, then connect a speaker once every other test is passed.
Do you have a scope? a sine wave generator? You can't really fix an amp easily without these tools.
The 3B is a hefty amp with 250W+ per channel at 8R. The rails are about +/-80V in older units and +/-90V in models built after the late '80s - they raised all supplies by 10V to increase transient power and reduce THD a teeny bit. With voltages like these you have to be very careful, and with the amount of energy that can be stored - that much more careful.
Fortunately, since Bryston's PAs are dual-mono, you can power up one channel at a time and test it without risking fireworks from the other channel.
Have fun
Kevin O'Connor
Bryston offers fantastic service support, so there is no reason for most techs to even bother.
In general, 99% of amps are tested and repaired without a load and definitely without a speaker. You eventually get to connecting a light bench load, then a heavy one, then connect a speaker once every other test is passed.
Do you have a scope? a sine wave generator? You can't really fix an amp easily without these tools.
The 3B is a hefty amp with 250W+ per channel at 8R. The rails are about +/-80V in older units and +/-90V in models built after the late '80s - they raised all supplies by 10V to increase transient power and reduce THD a teeny bit. With voltages like these you have to be very careful, and with the amount of energy that can be stored - that much more careful.
Fortunately, since Bryston's PAs are dual-mono, you can power up one channel at a time and test it without risking fireworks from the other channel.
Have fun
Kevin O'Connor
Thanks. I just aquired my first high quality DVOM yesterday. It is black and white compared to the portable automotive meters I have used in the past. I have a scope now as well. I have no experience with a scope except with a bit of audio analysis. My scope has a line out as well as sawtooth. Would that be a signal I could use for testing?
Thanks
Thanks
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