Quick question,has anyone encountered a noisy (intermittent static/pfft type noise) with any of their parts?
Amp is making some noises thru the woofers only,both channels,no signal.I'm fishing and hoping it may be something else.
Amp is making some noises thru the woofers only,both channels,no signal.I'm fishing and hoping it may be something else.
if both channels are equally showing same problem, I'm always suspecting on something which is common for both channels
is PSU common?
is PSU common?
Yes it is,its a modified standard +/- 23 volt pass type supply modified for approx. 46 volt output.The only change I made to it was to move the wire/cl60/u ground connection from the center of the +/- supply to the negative side to give me +46 volts.I may have a look to see if the soldering on that wire is suspect.Prior to moving the wire there was no noise from the other amp it was used with.Thanks for the tip Mr. ZM
moving NTC for chassis from previous GND to new GND is logical thing
hope nothing else is left connected to previous/old GND
hope nothing else is left connected to previous/old GND
Is the PSU the version with shared caps after the R or is it the kind with the split L/R final cap?
nothing else than to recheck all connections
though, to my liking , it'll be series secondaries and just one bridge
though, to my liking , it'll be series secondaries and just one bridge
Thank you for your input,I may have to get a can of cold spray and poke around with that.Tightening up slip on connector fittings on the PS did nothing as did poking around and moving wires with the end of a wooden spoon(hi tech test tool).
Perhaps the capacitors don't have the voltage rating for 46V for one bridge?
Better to move L1 to the positive side of the lower half of the supply?
Better to move L1 to the positive side of the lower half of the supply?
Ben, I meant caps staying in same arrangement, but that's just me , sometimes being superconservative
nothing wrong with schematic as is , and what's handy this way, itt can be again arranged as bipolar supply in no time
must be either some falling diode or critical contact
nothing wrong with schematic as is , and what's handy this way, itt can be again arranged as bipolar supply in no time
must be either some falling diode or critical contact
Noise update! I have tried to narrow down this intermittent issue.Amp on,pre amp on,no signal,intermittent noise thru both woofers (low level crackle and pops).Unplug either rca cable between pre and amp,noise disappears in that channel.RCA cable shields are part of,pre amp signal return, power supply commons,speaker negatives.These shields are tied together at the pre amp rca connectors and starred at the power amp power supply common.The power amp power supply common is lifted from "U" ground by a CL60 thermistor.Disconnecting the pre amp from the power amp and putting a scope on the pre amp rca's between center conductor and shell I found there is a low level dc (up to about 3mv) fluctualting level there.The fluctuations are not regular.Pre amp issue or crummy rca cables?P.S. At the input there is a 75k resistor to "ground", then a 1uf series capacitor in series with a 1k resistor tied to the 2sj74 gate .2sj74 gate sits at 1/2 the 46 volt supply.
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