SP10 Mk II vs Mk III

Re: number of electrolytic caps

The Service Manual for my SP-10 Mk2A identifies 24 'lytics in the main unit section and 8 in the power unit section. So, not much difference from Peter's count except he didn't include the power section which I've been told is most critical for 'lytic replacement. Of course the 2A replaced the multiple boards of the 2 with a single main board so removal should be easier.

Also, all caps are identified by a V, no WV or W.

Now, since I know so little about electronics, is there a consideration for replacing any of the diodes with new (faster) parts?

The diodes are by and large Germanium types. No one uses those any more except in special applications. They have a low forward voltage drop, compared to some other even more modern types, so probably they should not be "updated" indiscriminately. Schottky diodes, the latest craze, have a low forward voltage drop too, and in one case I know the Germanium types in the PS can be replaced with Schottky's. Bill Thalmann, the guy who serviced my 2A and Albert's tables too, used some Fairchild Stealth diodes here and there. Problem is I don't know where. The only advantage of messing with diodes is possibly lower noise, which is all it takes to make us audio-dudes drool with desire. Bill advised me as a general rule not to worry about it, using the "if it ain't broke don't fix it" approach. You could go crazy and start replacing film caps, if there are any. No real reason to do it.

Has anyone tried any of the various after-market outboard PSs available for the MkII? I know there is one sold via eBay and one sold by Vantage Audio (for much bigger bucks). The VA unit looks really nice, with separate transformers for each PS voltage output, darnit. I could build one but it ain't gonna happen in this lifetime.

One substitution you could consider for all those 1 uf 50 volt electrolytics are the Panasonic V series stacked metallized film caps sold by Digi-Key (part no. P4675-ND). These are very compact, low dissipation factor, non-inductive construction, and probably last much longer than any electrolytics.

RE: How about the 1pF electrolytic capacitor?

Just for the sake of others reading this message in the future....

The "1pF 50V" electrolytic capacitor listed in the SP10 MarkII Service Manual (for the Logic Circuit Board) is clearly a typo and SHOULD be listed as a "1uF 50V" electrolytic.

Like Lewm, I was equally confused when I noticed a 1pF electrolytic in the parts list.

The Part No. in the Service Manual (ECEA50V1) is correct, however, and identifies the correct value (1uF).

Chris

I just re-capped an entire MkII. You are correct. There is no 1pF cap anywhere, but then again I/we have found a few other errors in the Service Manual, most notably in the regulator circuit for the 5V supply in the PS module. One of the transistors is incorrectly designated as PNP type when it should be NPN (or vice-versa?), which caused me to have to give my PS to Bill Thalmann (super tech in Springfield, VA), who found the error quickly and easily. In point of fact, I doubt that a 1 pF cap exists; it is too tiny in value to manufacture with any degree of tolerance and moreover it is too small in value to make much difference. You get much more capacitance by just twisting wires. That's why I doubted its existence in the first place. There sure were a lot of those 1uF/50V caps, however, in the onboard electronic modules.