Recapping Boiler Plate
Now a bit of boiler-plate recapping info:
Note: Most of the original capacitor series used in these old units are long obsolete. Selecting replacements, from current manufacturers and their series, is also a task requiring a qualified tech. There are many parameters to consider (operating temp, value, value tolerance, life expectancy, effective series resistance, internal losses, size, etc.).
I am a Pioneer specialist, so, all my work references the Pioneer parts series. This is because my master recapping database is based on Pioneer part numbers.
The problem with most vintage gear (in excess of 25 years old), is the fact that electrolytic caps tend to dry out, since the electrolyte is moist, and must stay that way for proper function. Some caps drift severely, in the lower capacitance direction. Some caps fail open, and simply cease to perform whatever function they were designed in to do. Others that fail, do so by failing short, generally causing catastrophic damage to the unit. You may be enjoying a ticking time-bomb. Some will swell and leak, causing all kinds of corrosion damage to the circuit boards in the area, while others will literally blow up. Some caps measure OK on a capacitance bridge, but, in the circuit, leak DC, causing noise, bias shifting, instability, etc. I truly recommend re-capping gear you intend to keep and enjoy, or sell to someone you care about.
Re-capping generally requires a complete service manual, with all published supplements, addendums, errata, and modification sheets. Each board is gone through, electrolytic caps are each measured to get their physical dimensions (replacements must fit in the space provided). Not to fear, normally, since modern caps tend to be 1/3 the size of the originals (sometimes causing other problems). Then the caps are checked to see which Pioneer series they are in (indicated by Pioneer part number). Now you must attempt to determine what characteristics were important to the designers that established a specific Pioneer part number series. Hints come from what cap manufacturer series was used (usually, and hopefully, more than one), "if" you can find the very old data sheets you need (so far all the series I've encountered have been long obsolete), or mfg-to-mfg cross-reference lists. You must also track what kind of circuits the particular Pioneer part number series is used in (coupling, de-coupling, filtering, feedback, etc.). Without the original Pioneer part drawings, you must engage in significant guesswork, supplemented by informed/experienced reverse-engineering.
The next step is to attempt to find modern manufacturers for parts that conform to the design criteria determined in the previous step, followed by locating distributors that handle the replacement parts (in the onesy-twosy quantities you will need), and determine the per unit cost. (Note: I prefer to keep things original. I don't try to second think the original designers, unless the future owner pays significantly for an upgrade or modification. I do tend to use a bit better part than the original, but not to point of using the very expensive, esoteric, sometimes snake-oil parts). It gets to be a lot of fun when the part you need is not made by anybody in the size and/or voltage you need (like finding low voltage electrolytics in the sub-1uf values). Then you need to substitute a different kind of part altogether.
I then created an overall Pioneer database for electrolytic caps, which I can then draw on for other models down the line, and from which, I create a model-specific database, which shows each cap, on a per-circuit-board basis, with all the associated info (original part number, dimensions, value, working voltage, new mfg part number, distributor part number, price, etc. etc. etc.). The database also contains a table of consolidated data, where all like parts are grouped, used as a purchasing list for the model.
Here are some of my choices for the various types of caps that may need replacement:
1. For the low leakage or low noise lytics, I use Xicon LLRL series parts.
2. As to the standard 85degC, 20% lytics, I prefer to use the Panasonic FM series. When they are not available (possible, since this is a new series for Panasonic), I use the Panasonic FC or the Nichicon PWs. They are an incremental upgrade to the originals, in that they are 105degC, lower ESR parts, low tan-theta (relating to internal losses), plus, the Panasonics are pretty, with those gold labels and all.
3. For standard 85degC, non-polars, I use Panasonic SUs. No upgrade here, but there are fewer choices in this type.
4. For the parts "requiring" low ESR, of course I'm using the Panasonic FM, and FC Nichicon PWs. No upgrades in this case, except for the temperature tolerance.
When I order the caps for a unit, I usually order enough to do 3 or 4 units, since I usually have at least that many units of any particular model in my inventory, and I like to have the parts I need on hand when it comes time to do them. That way, I also have complete recap kits on hand for incoming restoration commissions. I also usually order at least 2 extra of any particular cap value. In that way, my on-hand inventory of caps grows, at minimal cost, which helps to cover the cases where the manual states the need for one value, when a particular board/unit actually has a different value (happens when designs are changed during the production of a particular model).
Emphasis:
Recapping is not the panacea for modern man. Recapping is the last thing I do to a unit, other than cosmetic work and final/performance testing. I won't recap a unit, until I have determined that it is fully functional. Recapping is more for an attempt at adding longevity to the mix. The last thing you want is for a 30-year-old 'lytic to fail short (they also fail open, and drift out of spec). Recapping is not a good "repair" technique (falls in the realm of 'shotgun repair' which I hate).
Enjoy,
Rich P