The Hayseed kit is just the beginning. No real formal "kits", that I'm aware of now that are worth a damn. Best start is to get in to the Forum stickies and read all of the 400 threads. Lots of good info there.
a.) With regard to the grid return resistors and the output caps, disregard the older 220kΩ / .1uf combo's. Current best practice is 220kΩ with a .068uf output cap. This combo will get you to closest timing factor of the original .047 with a 330KΩ. This will be for ALL TUBES. The 330K are over the rated max Ω for "fixed bias" from the tube manufacturer(originals and russian replacements). (*)
b.) Cathode resistors replace the grounded cathode link on the output tubes. 1/4W 10Ω resistors. Allow measurement of output power, and also serve as a fuse to shut down tube in case of a fault. (*)
c.) Screen resistors, 1/4w 100Ω, will mitigate or eliminate screen arcing which ruins the tube. See Dave's article on this
HERE (*)
d.) Silicon Diode Bridge in conjuction with the Hayseed main caps. The current selenium bridge (Siemens flat pack mounted to side wall underneath) is suspect at this point. (*)
Most of the parts you'll get are from mouser, digikey, Antiques electronic parts. With regard to electrolytics I prefer Nichicon's, although a lot of guys use panasonics. Audio grade caps are not necessary and will make your wallet squeal a little more. Nichicon UPW/UHE caps in the power supply areas, and UKL in the rest are good choices. Film caps (too many to have favorites, but the Yellow axials (Mallory) are good choice for output's and other areas where space constraints are not a problem. In tight areas, A radial film is fine, Cornell Dublier DME is my choice (very small physically). Film caps, get 600v or 630v.
Ceramic caps. Fisher used very high grade ceramics. Don't touch them unless bad.
IBAM/IBBA (individual BIAS Adjustment Modification/ Individual Bias-Balalance Adjustment). 2 different boards (DIY) doing the same thing. Highly recommended as you can dial in all output tubes to match in power, lessening strain between tubes (push pull pairs need to be closely matched so one tube isn't doing all the work.) (*) Bias the tubes for 70% to 80% of max dissipation(19W).
Biasing to 70-80% can lessen strain on output's enough that the original values on the output caps and grid return resistors don't necessarily need to be changed. But every little bit helps.
There are some threads on 400 restorations that are extremely detailed...Dig thru them and pull the latest stuff. If you have questions ASK! There are no stupid questions here. You'll get a bunch of answers(5 different guys with 7 different ways of doing something. They are usually all correct electrically but differ in appearance. Throw the dice and pick one). And a bit of leg pulling too (sometimes......Ok, more often than not). Do your Due Diligence studying threads.
RATE FEE's
Questions........................................................$3.00
Questions that require thought.............$5.00
CORRECT Answers.......................................$10.00
Dumb Looks, Face Palms, General Laughter...........STILL FREE!!!!
Take some underside shots of the 400 (quarter it) and post. Get in close as a shot from 4 ft away won't show enough detail.
Service manuals for Fishers are based on Serial #'s. 1965 could be early or late. Early 10001 to 47999 or so. Late starts at 48001.
The biggest tell other than the serial is the number of RF/IF Tubes (tuner). Early has 5 tuner tubes with V3 being a 6HS6.
Late has 6 tuner tubes with V3 thru V6 all being 6BA6.
Post your serial #.
(*) Items listed above are in the
COMMON Parts for FISHERS thread in the Stickies at the tops of the Forum page.
