I'd avoid long leads with the caps standing up off the board, that's an invitation for them to act as an antenna and introduce stray signals!Īlso, check your schematic for secondary power supply circuits. Also would simply not fit in the space in one case, the originals are in a tight line all together, no room for the film caps. You can replace bipolar caps with film IF they will fit - check lead spacing, I could not use them in my Kenwoods because the original lead spacing is either 2.5 or 5mm and the film caps were 15mm lead spacing in that size. The orange caps are low leakage, use Nichicon UKL or the equivalent Panasonics. If that sound like it could work, then I'll just order that. Silmic II for the higher uf in the 3 other boards mixed with KZ for the lower uf and bipolar. KG for the 4 filter caps and Panasonic for the rest of the power supply board. Most of the "bypass" (lower microfarad and voltage) are orange CE (MR?) and bipolar.Įdit 2: I'll tell you what, I'm getting mad overthinking it, let's say I'll use: I'm assuming they are on the signal path. Also two capacitors like this on the power amp board. Try to identify where a circuit begins and ends as they usually contain both big caps and small caps."Īctually noticed I do have a few like that on the "tone amp and control" & "protection" boards. Likewise if you see a cluster of 1000uF or higher caps, it's probably power supply. If you see a string of those, it's probably the signal path. In the signal path, the main caps are often something like 100uF or 220uF and the coupling/bypass caps are around 10uF or 22uF. What do you recommend in the power amp, Panasonic too?Īs for space I thing there is space enough around every capacitor, it seems to be easy to work on this amplifier but I'll double check before ordering.Įdit: Big beard, After reading you it makes a bit more sense now "As to identifying the signal path, well it takes some study at first but when you dig into amp design it becomes quite clear and intuitive.Probably Panasonic then, however there is a few bipolar that probably be the Nichicon green. My plan has changed a bit since reading you, I'll still stick with Silmic in signal path, I'll have to go KG for the 4 filter caps as I can't find anything else in 50v 10000uf but KW.
Signal path audio manual#
I have the service manual and schematic found on hifiengine too, I actually printed it. What would be the incidence if I go up in voltage on many capacitors? Sorry, by going up in capacitance I meant voltage.Sounds like I remember it, very clean and true to source.ĭon't sweat capacitor choice too much, if you don't like the results, other than the filter caps (which are not in the signal path anyway) they are cheap enough to replace with something else. I have the advantage of being the only owner of this amp, so I more or less remember how it sounded new (forty years ago almost). New caps will also run cooler in places like the power supply due to lower ESR, too. All the small caps were high on capacitance and higher than I would like for ESR although only one or two were way out of spec, but that's testing at low voltage and no load, I'm sure they were all getting pretty close to failure. I tested all the caps after I removed them with a "toy" component tester, and most of them were OK. Will do the same thing for the other KA-80 I got for next to nothing recently too. I've had quite a few fail over the years in that Kenwood, so I replaced them all while doing the caps. Solid state parts tend to last more or less forever barring shorts or other component failure with the exception of Zener diodes. Given the price (mostly inexpensive) it's rather foolish to my mind not to replace the parts that are likely to fail sooner rather than later in these old amps.
The caps Kenwood used are quite good, with low leakage and low ESR even forty years old, they are just dying of old age. There is no need to use exotic capacitors (although excellent quality is a good idea). Since the board is component side down, all the caps get a lot of heat.
I used all audio grade caps at 105 degree rating in my KA-80 for the simple reason that the board is inverted and that amp runs very warm.
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