• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Capehart 114N2 6L6 Amp Pics+Restoration

they're not really polarized exactly, but usually the neutral is the wire that carries straight through and the hot is the one going to the wiper. Electrically it works either way, but being "correct" will depend which way the cord is plugged into the wall. Possible someone replaced the socket. I'd probably consider changing the cord to a polarized one. Maybe even consider a grounded cord, and ground the case of the variac just as a bit of insurance in the event something goes bad with it.

I'd build a cover for that thing. Its connected to the wall, very easy to get a case of the zappies from it. It will get warm when used with a high current load so just keep that in mind if you do build a case. My old SeCo one uses perforated sheet metal.
 
Yeah, that's what I figured. I'll go ahead and wire up a polarized cord in that case. Probably not going to bother with a cover -- any time I'm using the variac, there is also going to be exposed wiring in whatever amp I'm testing, so I'll be exercising caution anyways.
 
Opened the housing up to check the polarity, I think it was re-wired at some point, but the new wiring does have the wiper as hot and has the switch on the wiper side. So, just needs a proper polarized plug and it should be ready to go. Also, you have the option to use either the full winding or the part-way tap that allows for over line voltage. I'm going to rewire without the tap, as I don't anticipate needing over 120 v or whatever my line is.
 
thats how mine is. Didn't want to accidentally over-volt anything. Full open is just line voltage.
 
The wires are so disgusting, I think I might completely re-wire it except for the transformer and choke leads.
 
plastic but oozing that sticky gunk? Ancient PVC does that when it starts to break down. Whatever is in it seems to attack the copper wire inside. usually see green goo coming out of the ends. It also has a funny sour smell.
 
No, cloth but crusty with a distinctive musty/mildewy smell. The transformer and choke leads had some sort of waxy coating so they fared a bit better. Also, the wire runs are messy and some are excessively long. For some reason, the heater was re-wired, removing the DC B+ reference and just running a simple ground return config. I think the amp was modded/serviced while still used in the console, because it's clearly been worked on but no addition of a power switch, power cord, or normal speaker wire terminals.
 
oh, that usually just gets dry but it still works unless disturbed too much. The insulation crumbles and cracks when moved around. Rubber wire from the pre-war era is the worst. It turns to dust without even being touched. When I pulled the chassis out of my 1939 Philco there was a pile of multi-color dust crumbles under it and much of the wire inside was bare or covered with random crumbs of colored rubber.
 
Hahahaha, yeah, there is one rubber wire in this amp and the insulation looks heat damaged, it's quite warped. I mostly want to re-wire the unit so it looks prettier and so I can eliminate a bunch of the musty smell. Should be a fun project too, I bought four spools of new cloth wire from Antique Electronics Supply.
 
Ok, so I've learned a ton working on this thing, quite an educational project. I do have one question about elevated heaters. The schematic I'm finding online has the heaters elevated to 30v dc in the usual fashion, but there is no evidence inside the amplifier of the elevated heater supply ever existing.

Obviously, it's trivial to re-implement the elevated heater; simply a matter of adding two resistors for the voltage divider around one of the tube sockets. But is there any reason I should hesitate to do so? Like, is it possible my amplifier is a later version and the elevated heater was removed for a reason other than cost? I can't imagine why this would be the case, but thought I would ask.

Also, just out of curiosity, anyone able to speculate as to why this amplifier has two big chokes with an 80uf cap in between? And is there a reason that the negative of this cap is floated 16 ohms above ground? I have a schematic here.

farnsworth_television_radio_corp_21n2_pg18-23.png
 
It would be good for your phase inverter tube. Looks like a split load as the second triode, so the cathode will be at a fair number of volts above ground. Bringing the heater up some will reduce that voltage difference so the tube ought to last longer.
 
Ok, that's good to know. Perhaps it was eliminated for cost and wiring complexity reasons, as they replaced it with a simple ground return wiring scheme. The area near the four 6J5 sockets is extremely cluttered without heater return wiring, not really sure how I'm going to pull it off...
 
can use any of the tube sockets on that winding, if the output tubes are using it you can tie it to the cathode. That should be good for ~25v.
 
Looking forward to read your listening impression. This is a lot of iron for only 2 6L6 power tubes. Better be good after all the effort you put into it.
 
Got some updates on the re-wiring process. Here's the before pic:

20201229_205236.jpg

After re-wiring the 6J5 socket area:

20210101_011613.jpg

Added 6J5 coupling caps, new input connector, the heater B+ voltage divider, and some of the heater wiring:

20210112_173715.jpg

Nothing soldered yet, I'm going to do one more check against the schematic before I go ahead with that. It's taking an insane amount of time, which was expected. I'm learning a ton and the amp looked like a catastrophe when I got it, so I think this is worthwhile. I enjoy working on gear as much as listening anyways. Still need to redo the wiring on the bottom half of the amp (much less and no tube sockets, should go faster), new caps and resistors, power switch, speaker binding posts.
 
Finished up the first half of my restoration project, and made a quick video -- I'll leave it here in case anyone is interested:
 
Ok, so I've finally gotten around to working on the N2 again. I have replaced all of the carbon comp resistors, the driver-output coupling caps, and the cathode bypass caps. Just need to solder everything and finish the heater wiring. Should be able to power it up and listen tomorrow. It's certainly a bit excessive to completely re-wire and replace all the passives, but I find that doing thorough restorations helps me learn.

The amplifier is class A and seems fairly well designed, so I am optimistic about the sound. Wish I had another for stereo, but all the Ebay sellers offering these set delusional prices based on their conflation of the valuable 2A3 Brook/Capehart amps and the far less valuable 6L6 ones.

image0 (3).jpeg
 
I've enjoyed watching your work on this. I have the PPP 6V6 version of this and am considering doing the same with it, looking forward to your impressions of it.
 
For those who don't know, any of these Capehart amps, be they a little 100 series like this one or one of the big Brook-built 400 series PPP 2A3 monsters, have so much and such large iron on them because the amp's power supply drove almost everything in the console. The tuner assembly and any other controls didn't have their own internal power supplies - and a Capehart tuner is a complex beast with a LOT of tubes.
 
You must log in or register to reply here.
Back
Top Bottom