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Fisher 400-C preamp: resurrection

Sam Cogley

Sam Cogley

Last of the Time Lords
Subscriber
I assume most of the tube gang has seen the wrecked 400-C in my Fisher thread. I fully intend to either bring this unit back from the grave or use it as a parts supply to rebuild another incomplete unit, should one wander by for a reasonable price.

First up - does anyone have large, hi-res photos of the innards and the faceplate? I'm trying to figure out how a few things are supposed to be connected to each other. I have the bottom cover off, and I'll get pictures up tonight or Sunday. Except for the hacked-out switches, the internal issues are far smaller than the external - fortunately.

Second - does anyone know where I can find a schematic and/or service and user's manuals?
 
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Thanks!

After looking at a one picture I was able to find of the innards, I seem to have a bit of an issue - I only have half of the phono/tape switch. Arrgh! Fortunately, I have a pile of NOS military open-frame rotary switches I snagged at an auction. Maybe I can dismember one of those and use the first half as a pattern to rebuild the rest. Now that I think of it, If I could get a good look a the stereo mode switch, I could probably do the same over there.

Edit: I looked at the switches I have. The plates are a tad bigger than the original switch, but they have the same number of terminals per plate. The rotary contact plate is a bit different, but I should be able to fabricate those with some thin sheet brass. I'm not sure if I'll build a whole new switch around the larger plates or find some way to join two slightly mismatched sections. I have the healing touch! :D
 
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i can supply pics of anything you need. the face plate is off mine so if want dimensions i can do that as well. p.m. your addy and what you want pics of.
 
Here's a big pic of the innards. Those white Japanese foil/film caps don't seem to be original, and one resistor looks like it had a very bad day. A shotgun approach to the electronics might well be in order, considering the type of abuse we're looking at here.
 

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Sam, do a little research and find out whether the 400, 500, or 800 receivers could be a donor for guts. My 800 is cosmetically mint and the 500 works well, but I could part with any if one would get the preamp up and going.
 
Karma certainly works in strange ways, and I've felt blessed with some good luck lately. When I acquired this lot of Fisher gear, it was obvious from the start that the 400-C was going to present the greatest challenge - and potentially provide the greatest reward. I've been doing my research, gearing up to tackle some of the harder jobs like fabricating a proper faceplate and the missing rotary switches. A few days ago, I answered a CL ad for lots of vintage gear, including some Altec and JBL speakers that interested me, as they'd be a nice match for the all-Fisher setup. The seller turned out to be (like many of us) a collector of audio gear, and in the course of conversation I mentioned that I had a partial 400-C, which lead to the revelation that he had some 400-C pieces (originally we thought they were the missing parts from this exact unit, but that would needlessly complicate this narrative) in his closet. Tonight he pulled them out and I drove back over to work out a deal. As it turns out, he had a mostly-complete but butchered 400-C, not just the missing parts. Almost everything missing from 400-C #2 is on 400-C #1, so now I have all of the parts needed to build one complete preamp except for the rotary and toggle switch knobs. The only part missing from both is a short length of armored cable, but both units have a longer section of the same stuff. The chassis acquired tonight is in far better shape than the 400-C that started this thread, so it will provide the frame for the rebuild.

There will still be lots and lots of work to do before I the project is completed, but tonight advanced my position by leaps and bounds. I owe everyone who's been helping with this project an extra-big "thank you!"
 

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Wow....what luck.Gotta love CL for you never know what you will find lurking in someone elses junk
 
Karma extracted a price, though. Earlier today I was trying to get my table saw outside to cut a piece of wood needed for a Christmas project. I ended up dropping a rather heavy metal and MDF end table on my foot - it hit, one point of the table top down, directly on the middle toe on my left foot - dead center between the first joint and the body of the foot. As bad as it hurts to move the toe, I fear it's fractured. I couldn't drop that table in that manner again if I tried 1000 times.

And never fear, when this project gears up I'll take plenty of pics.

Interesting note of difference between the two pres - #1 (nasty looking) has split treble/bass control pots that used two knobs per shaft. #2 has conventional linked two-gang pots.
 
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Wow! That's amazing that you found the parts for your 400C! Very clean faceplate, should be a beauty when it's all done. And here's hoping that your foot will be OK!
 
Dam Sam, be careful with that axe!
Over the past 15 years, 40% of the disabling injuries amongst people I have worked with have come at home. Make sure you are wearing safety glasses, and in your case, steel toed work boots might be the ticket as well. Ripping wood, soldering, and digging thru estate sale basements is hazardous stuff.

Congrats on the "new" 400. That will help immensely in your quest.
 
Sam, that is awesome that you were able to find another 400c to complete your project. That faceplate look very nice.

Sorry to hear about your toe. That sucker is gonna be sore for a while. Are you gonna have to go let a doctor take a look at it?
 
sheltie dave said:
Dam Sam, be careful with that axe!
Over the past 15 years, 40% of the disabling injuries amongst people I have worked with have come at home. Make sure you are wearing safety glasses, and in your case, steel toed work boots might be the ticket as well. Ripping wood, soldering, and digging thru estate sale basements is hazardous stuff.

Congrats on the "new" 400. That will help immensely in your quest.
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www.records said:
Sam, that is awesome that you were able to find another 400c to complete your project. That faceplate look very nice.

Sorry to hear about your toe. That sucker is gonna be sore for a while. Are you gonna have to go let a doctor take a look at it?
Click to expand...

It's the size of a smallish egg right now, but the pain has subsided somewhat. I don't know if that means the damage isn't as bad as first feared, or if the swollen tissue is immobilizing the damage and acting as a pad. Fortunately, I'm done using the saw for a while. If it doesn't improve, I'll have my aunt (who is an MD) take a look at it this weekend. For now, I'm just being careful how I walk.
 
perchdog said:
Sam,
Awesome find... i have to admitt i am jealous, that plate looks nicer than mine.
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In person, there are some flaws that aren't as apparent in that pic. Some of the lettering is damaged around the EQ switch hole and there are a bunch of light scratches - one is almost the entire height of the faceplate and doesn't show up here at all. That's not to say that it doesn't display well, but it shows its 50 years.
 
Now the big question - what exactly are the specs on those dinky little bulbs used to illuminate the jewels?
 
Not audio related but get that foot checked. I mashed my foot when I was 18 trying to get an engine hoist out of a truck by myself. Being 18 and indestructible I continued with the engine swap and never had the foot checked out. My foot didn't heal right and by the time I was in my late 30's I was a regular at the local foot doc. Two years ago i had to have a nail removed premanantly......
 
The foot is healing OK, an x-ray revealed no breaks in the bone.

No one has a clue what those little screw-base incandescents are?

On both 400-Cs, the shorter piece of armored cable is missing. I can cut one of the longer pieces down, but how do I go about cutting the shield without damaging the wires?
 
Well, Rat Shack has an E5 bulb in both 6V .1A and 6.3V .15A. The Sam's manual calls for 6.3V .1A. I guess I'll get six of each and give both types a try.
 
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