The whole shebang: At this point, everything is stock except: the trem section has been recapped; the power cord was replaced with a three wire cord; the second channel inputs have shielded cable. The original caps included Orange Drop[tm], Black Cat[tm], Astron[tm] (the metal body caps), General Instruments[tm] and mica disks. There's a hole for an extra tube, but I don't know what it would be used for. There are no extra holes on the panel for additional controls; perhaps the second channel could be replaced with a reverb. The through holes for wires had no grommets. The extra hole at the upper left was probably used for a different output transformer with wires coming out both sides. The currently unused switch at the lower right was a polarity switch before the power cord conversion to three wire.
|Signal path guts: Here's a closeup of most of the signal path and tremolo guts. This is classic, mass production, flying lead, point to point wiring from the 60s. As much as possible hangs directly off sockets, controls, and jacks, and the chassis is used as the main ground path. Components came standard with longer leads to facilitate just such construction; note the long resistor leads. The larger Xicon cap from the leftmost tube socket required a lead extension to reach the terminal strip the original cap reached. (I have since learned not to buy caps with leads this short!)||Ground details: Ground straps (braid) are used for some of the signal grounds. This amp has somewhat of a star ground system, using the chassis to connect the various subsections. Note the wire and braid soldered to the tube socket mounting bolts; this was to insure a good electrical ground for the socket shields. The terminal strip to the right is soldered to the chassis rather than bolted; other strips were bolted. Presumably this was because manufacturing chose to place terminal strips where no holes existed. The solder blob between the sockets is another terminal strip mount/ground. The body of the Astron cap in the lower middle is used instead of connecting to the lead at the end; there's no grounding there. (That cap is C104 on the schematic.)|
|Tone and signal caps: Here the pot body is used as a ground path; this is done on both tone pots. Neither of these pots has any soldered path to ground; both depend on the pot construction and star washer for their ground connection. The amazing thing is that this amp works, and the hum and noise are reasonable. It's not the quietest amp around, but it's not that bad, either. Note that the pots were oriented so that the lugs could be soldered together rather than run a wire between them.||Soldered mount detail: Here is a better view of a terminal strip mounted with solder rather than a bolt. As with the case noted above, there's no electrical need for this, as there are no leads attached to this terminal. In fact, they snipped off the top of most of the ground terminals! Components are mounted on the terminal strip through-holes as well as the terminals proper. The RCA jack at the bottom, like the output jack (not shown), depends on the bolts and lock washers for electrical ground. The terminal strip at the far right is mounted only at one end; the other end is hanging free in space.|
Copyright 2005 Miles O'Neal, Austin, TX. All rights reserved. Miles O'Neal <roadkills.r.us@XYZZY.gmail.com> [remove the "XYZZY." to make things work!] c/o RNN / 1705 Oak Forest Dr / Round Rock, TX / 78681-1514