Hi guys, I picked up this preamp with a hum problem. The previous owner said it was just in the phono stage but it is also in the line stage. I measure 33.96 volts on both left channel stages, but only 23.58 volts on both right channel stages. Someone replaced the caps. on both gain stage boards with Nichicon KZ and ES but not on the power supply boards (this model has two volume controls and two p.s. boards). I'm going to replace the eight electrolytic caps. on the p.s. boards, but I see another problem. On the p.s. board that powers the right channel, someone replaces a resistor and a small cap next to it (they both measure fine). My question is about a mystery component, there are several of them on all of the boards. I think they are some type of radial leaded cap. but I'm not sure. There are two on each p.s. board, marked with 10000K and 100 with a W inside an oval on each one. One of them (on the right channel board where the small cap and resistor were replaced) is not measuring like the other three, a much lower resistance and as a short for capacitance. Thanks for any help, Ron.
Those are 0.01uf 100V caps, perhaps the WIMA brand, probably bypassing the electrolytics.
Remove the bad cap, but it may have damaged a resistor, etc. http://www.hifiengine.com/manual_library/superphon/revelation-basic.shtml
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Thanks rayma, I might as well replace all four in the p.s. boards. Do you have any replacements in mind, something quality. The electrolytics are going to be KZ or FM 100 uF 50v for the four radial 100uF 35v caps. As for the four axial 1000uF 35v caps I ordered Nichicon VX 1000uF 50v. I've read where Stan Warren (Superphon) suggests bumping these up to 1500uF, what do you think and is there a better axial cap. then the VX or are they good enough? Thanks again, Ron.
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