Good afternoon,
your help about a Genesis four channel amplifier ... may I say: "half working".
It came into my desk with one channel in short circuit (two darlingtons blow and 47 ohm SMD resistance on a preamp stage broke); after replacements the amplifier works only on right channels.
Main voltages: + and - 18 are ok; +31 on positive rail, -28 on negative rail: is this little difference right ?
Another question: why signal of R channels is present into INV pin of the preamp stage (and these channels play good music), but into L channels pin INV is not connected ?
Sorry but without a schematics it is difficult to understand input stage and, mostly, the crossover circuits and the subwoofer module !!!
Thank for your help. Some pictures of the circuit are attached
Giovanni
your help about a Genesis four channel amplifier ... may I say: "half working".
It came into my desk with one channel in short circuit (two darlingtons blow and 47 ohm SMD resistance on a preamp stage broke); after replacements the amplifier works only on right channels.
Main voltages: + and - 18 are ok; +31 on positive rail, -28 on negative rail: is this little difference right ?
Another question: why signal of R channels is present into INV pin of the preamp stage (and these channels play good music), but into L channels pin INV is not connected ?
Sorry but without a schematics it is difficult to understand input stage and, mostly, the crossover circuits and the subwoofer module !!!
Thank for your help. Some pictures of the circuit are attached
Giovanni
Attachments
Hi jkrokenberger,
thanks for your reply.
I measured rail voltages at caps terminals and I noticed a difference (litte, of course) beetween + and -.
Boh, probably it's normal, but tomorrow I'll make some tests changing ground reference.
For the input into preamp module, probably you're right: for bridging purpose, R signal is inverted and L signal are in fase.
So if i don't have any signal into L modules into normal input, the problem are into input stage and / or crossover
thanks for your reply.
I measured rail voltages at caps terminals and I noticed a difference (litte, of course) beetween + and -.
Boh, probably it's normal, but tomorrow I'll make some tests changing ground reference.
For the input into preamp module, probably you're right: for bridging purpose, R signal is inverted and L signal are in fase.
So if i don't have any signal into L modules into normal input, the problem are into input stage and / or crossover
Hi Lenin,
after measures you've suggest, i've changed all OP amps (the originals were TL074CN, but I've TL084IN only) and now signal arrives at the output stages; potentiometers and switches are OK.
I don't understand yet because there is a difference between both positive rails (+30 V) versus both negative rails (-27 V): investigations in progress
Do you know nominal idle current of this amp ? Without any TIP in place it consumes 0,8 A
Thanks and happy easter from Italy
Giovanni
after measures you've suggest, i've changed all OP amps (the originals were TL074CN, but I've TL084IN only) and now signal arrives at the output stages; potentiometers and switches are OK.
I don't understand yet because there is a difference between both positive rails (+30 V) versus both negative rails (-27 V): investigations in progress
Do you know nominal idle current of this amp ? Without any TIP in place it consumes 0,8 A
Thanks and happy easter from Italy
Giovanni
Hi guys,
I made some other tests because 2 - 2,5 A is too much for this amplifier.
Mi problem is my "sound source": an old Ipod with battery carger always connected because battery is broken.
Probably a short circuit between supply ground (connected trought a DC/DC converter to my Ipod) and audio signal ground is the cause of this high idle current (with another audio source, Genesis take 0,8 A only).
And sound is much better
Thank everybody.
Giovanni
I made some other tests because 2 - 2,5 A is too much for this amplifier.
Mi problem is my "sound source": an old Ipod with battery carger always connected because battery is broken.
Probably a short circuit between supply ground (connected trought a DC/DC converter to my Ipod) and audio signal ground is the cause of this high idle current (with another audio source, Genesis take 0,8 A only).
And sound is much better
Thank everybody.
Giovanni
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