I have a CR1020 and when I first turn it on and rotate the volume knob the speakers produce a loud cracking noise as I rotate it, as if the pot is dirty. After several attempts at spray cleaning the pot the noise is still there, and I discovered it only does it for a minute or so after I turn the unit on. If I turn the unit on and wait about a minute, then rotate the knob, there is little to no noise at all. Is this an indication of something else, such as caps or resistors in need of replacement? I only ask because the noise is almost non existent if I wait before rotating the knob, thinking something is warming up or charging up in that period.
Thank You in advance for any information that leads to a possible solution.
Thank You in advance for any information that leads to a possible solution.
Look for an electrolytic coupling capacitor just before the volume pot, and replace it (in each channel).
They are leaking DC into the pot.
They are leaking DC into the pot.
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Suggest check the bias to make sure all is well, takes like 2 minutes... It's a vintage unit, caps should be checked for any signs of stress etc...
The culprits would have to be C502, preamp sections A and B. 10µ / 25V, type may indicate RB (hard to read). Probably not a low-leakage type but possibly a relative, as it appears that the Elna RLB series also goes as RB (LL). The legend just says "RB Capacitor", great help indeed. Are these some of the orange Elnas? Would be the first failed ones that I'd have heard of then.
Not too much choice among low-leakage electrolytics these days. Digikey has Nichicon UKL series caps, which would seem a suitable replacement. UKL1H100KDD is a 10µ/50, 5 mm dia.
If there are similar issues with the treble and presence controls, you may want to recap the entire section. Others that IMHO would benefit from being low leakage would be C509 (47µ/6.3) and C510 (100µ/16), for the others I'd go with plain ol' Panasonic FCs or whatever your standard types are. I'd generally pick the same capacitance and the largest voltage rating that matches the original mechanical dimensions (diameter), unless it gets silly high.
The preamp has at least 8 more of these 10µs, and 4 100µs. There are two caps marked "low noise", C405/406 (47µ/6.3), now those could be the real deal orange Elnas. Capacitor popcorn noise has been shown to be directly related to leakage and can even be used to characterize it, so low noise = low leakage.
Pretty fancy preamp circuit, but then what do you expect from Yamaha's flagship receiver. Would consider adding a little capacitor in parallel with D502-R511 to reduce output stage asymmetry there - a handful µF would be fine, polarity observing. 100 nF of film across D531/532 might be worth a shot as well.
Not too much choice among low-leakage electrolytics these days. Digikey has Nichicon UKL series caps, which would seem a suitable replacement. UKL1H100KDD is a 10µ/50, 5 mm dia.
If there are similar issues with the treble and presence controls, you may want to recap the entire section. Others that IMHO would benefit from being low leakage would be C509 (47µ/6.3) and C510 (100µ/16), for the others I'd go with plain ol' Panasonic FCs or whatever your standard types are. I'd generally pick the same capacitance and the largest voltage rating that matches the original mechanical dimensions (diameter), unless it gets silly high.
The preamp has at least 8 more of these 10µs, and 4 100µs. There are two caps marked "low noise", C405/406 (47µ/6.3), now those could be the real deal orange Elnas. Capacitor popcorn noise has been shown to be directly related to leakage and can even be used to characterize it, so low noise = low leakage.
Pretty fancy preamp circuit, but then what do you expect from Yamaha's flagship receiver. Would consider adding a little capacitor in parallel with D502-R511 to reduce output stage asymmetry there - a handful µF would be fine, polarity observing. 100 nF of film across D531/532 might be worth a shot as well.
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