Sir spanish_inq . . . . .
I see that the unit has the capabilities of taking in audio inputs from:
- Tuner
- CD
- Line / VCR
- Tape 1 Play and Rec
- Tape 2 Play and Rec
I also see that the main R and L power amplifier portions of the unit are using discrete component construction instead of an “AMPLIFIER in a sealed black box” . . . . . ( POTTED MODULE) type of construction.
I also heavily suspect THAT section is being the area of the trouble, with some semiconductor breaking down and avalanching just for the instant(s) that you are hearing the loud pop/snap/crashes.
Otherwise it is being GOOD for 98% of the other time.
Gradual shift of temperature of operation of a part might be the factor triggering that, at either some cool condition at turn on, then passing up through a gradual temperature rise variance, until it finally reaches its normal operational temperature.
If being my problem to analyze and then pinpoint the problem area . . . .
I would put the FUNCTION switch to LINE/ VCR and have nothing plugged into those inputs.
Then the first listening session would be to have the balance control at mid range and volume up to about half of max position, so that you should definitely hear any POP sounds while you are in the room but working with another task, as it just might take an hour(s).
If you get that POP you need to differentiate between origin from Left channel or Right channel or both.
(If you look at page 6 you will see that 11 transistors are direct DC coupled within your power amp section of a single channel, so if a semiconductor acts up, you could hear a snap, crackle, pop or bacon frying sizzles that would be created at those bad times. )
If you are not able to differentiate, if it’s only being of such short duration . . . . then . . . . ..
You set up again for another day where you swing the balance control to extreme Right or Left channel and wait for the noisy effect to come along.
If no result within those several hours , swing the balance to the other channels extreme and wait out that day.
Once the channel is isolated, you take that channel and see if the effect is present on another test day on that previously bad channel, but this time with the volume down at minimum.
These procedures may be sped up if you are LUCKY and it starts showing up its problems quickly. . . . I was just expecting a possible worst case intermittent.
You would want to have thus ascertained what is being the bad channel and does the volume control have an effect upon its level of severity.
- After long listening session the issue somehow disappear, I can change source without this noises, etc.
This suggests that the problem is most likely to be present from a stone cold start up to the temperature where it finally reaches a stable operating temp.
Questions ?
73 de Edd