Not mad (mad implies a loss of control), more disappointed and a bit angry / resigned.
Water under the bridge at this point, on the bright side there's no smoking ruins to repair.
NOBODY has so far forced me to "go nuclear"....
I didn't replace the diodes on one side after replacing the blown ones.The originals are on the side that's giving problems, they tested OK though
we are looking for differences between the two amp channel COMPONENTS.
WHICH DIODES, NAME THEM fer crying out loud - how can I THINK on the problem if I don't know?
You should change them first, and HOPE that it straightens this out.
Also list the component (Qxxx) and part (ksc1845) number of
every transistor that has been changed, even if they have been changed on both channels, INCLUDING the outputs. I HAVE to know what we're working with.
otherwise, we've got a LOT of digging(measuring, investigating) to do,
to root out differences of probably less then 0.1 volt
the difference in voltage could be a single component, or a group of components that were damaged during the failure, and while still testing somewhat functional, have been altered enough to cause this.
This amp is almost identical to the sx-3900 and sx-d7000, so:
(but the board layout is quite different in places)
and confirming the instructions on that page are back asswards...
vr1, vr3, vr5 (odd # parts) are the right channel
vr2, vr4, vr6 ( even # parts) are the borked left channel, which has too high of a minimum idle current. borked....
measure some voltages:
Thermal diodes -
1. the voltage between wire wrap pins 309(black) and 310(red) of the awh-114 amplifier board, right channel
2. the voltage between wire wrap pins 307(black) and 308(red) of the awh-114 amplifier board, borked left channel
Do this very quickly when the unit is just turned on,
and cold - so that BOTH thermal diodes
are at
nearly the same temperature.
IF they are significantly different, then these (pita) readings are needed:
back all 4 idle pots down to zero ohms, so we are comparing apples to apples
and do this:
1. connect the red dmm wire to pin 5 (+54v regulated) of the awh-114 amplifier board.
2. probe with an insulated (all but the tiniest portion of the tip) black probe
2.a. q115 emitter
2.b. q115 base
2.c. q116 emitter
2.d. q116 base
note: LATER we will measure (with the POWER OFF) the resistance of R127 and R128
This is the current source for the thermal bias diodes, and a difference here WILL alter the expected thermal bias diode junction's baseline voltage drop.
In close quarters, measuring live boards, I first solder tack wires to each of the measurement points and bring them out and over, securing them to a piece of cardboard with their descriptions of where they are coming from written on the cardboard.
If they are different we will have to correct this.
If they are THE SAME, we :sigh: will have to dig lots deeper.
