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Fisher 400 rebuild questions

satterfi

satterfi

Member
My father-in-law gave me his Fisher 400 last week. It’s in great cosmetic shape and seems to be in good working order. I’d like to rebuild it and need advice. It’s an early version, ser. # 18164*.

I’ve searched the archives and have a fair idea of what I need to do.

I haven’t read where anyone has replaced the multi-section caps C75 and C77. Aren’t these caps just as susceptible to failure as the other electrolytic caps? C77c (200uF) is part of the voltage doubling circuit, shouldn’t it be replaced? It looks like a rats nest under C75, is it worth it?

CR1, CR2, (in the +B circuit) I don’t know the specs. Are 1amp diodes like a 1N4007 suitable?

C80, C83 .01uF, 600V, molded, I don’t know what ‘molded’ means. What is an adequate replacement?

Would Vishay MKP 1845 be acceptable coupling caps? http://www.vishay.com/docs/26023/mkp1845.pdf

Any advice would be appreciated.

Jon
 
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Welcome to AK!

I can't answer your questions but wanted to let you know someone was reading your post and I am sure those who are knowledgable will chime in shortly.

Barry
 
FSISHER 400 Resoration

Jon,
Replacing the muti-section caps is not typical. Most common restoration item is to replace the coupling capacitors (prevent bias problems due to leakage) and for 500/800 series receiver (not sure about 400), replacing the selinium rectifier (fire hazard). If your receiver powers up and is working correctly, your are mostly done. I would need to look at a schematic - I own a Fisher 500C which I repaired and restored - but, simple clean up and bias cap change and you should be set for daily use. A couple of other notes on Fisher recievers 1) check that the chassis is not electrically hot - cap to chassis sometimes leaks and 2) whatever your do, stay out of the tuning section. If you start replace parts, will require a complete setup and realignment.
Cheers -ALBQ

PS. Google Fisher receivers and you will get a ton of info
 
I would say that yes, the electrolytics too are suspect for problems and should be replaced...old electrolytics will not often hold up, especially if the receiver is subject to heavy use.
We have worked on these and replaced all of the electrolytics. It is somewhat difficult to replace all those caps but using the JJ electrolytic cans helped.

"Molded" caps are usually plastic encased paper and should be replaced.
 
Fisher 400 Receiver

I have a cosmetically near mint Fisher 400 receiver that will not power up. My technical skills go about as far as checking to make sure it is plugged in and whether the fuse is good!

I debate as to whether to attempt to fix it (cost vs. return) as it may be something simple. Is anyone familiar with any simialr issues on the 400 that would cause the unit to go dead?

It's a shame that i may end up as a parts unit as I am not willing to spend $100's to fix it when that is all they are worth. The shame is that it looks about as nice as you will ever find one and I hate the fact that it could be something simple and I rip it apart when it is a $10.00 fix.

Barry
 
If the fuse is intact, sounds like maybe the power switch died "open" instead of "closed"! I think bad switches are pretty common on the old Fisher receivers.

If you decide you don't want that 400, Barry, send me a PM :-)

As to re-hab'ing the Fisher 400 for Dummies, I (a 400 Dummy if there ever was one) humbly offer this:
http://audiokarma.org/forums/showthread.php?t=78700&highlight=Fisher+400+fotos

I am squarely on the fence about whether or not to replace the electrolytics. That first cap section in the voltage doubler for the B+ takes a lot of punishment, I guess. If the can is at all warm, it's probably cheap insureance to replace at least that first section (e.g., with an under-chassis, single value electrolytic).
 
i just finished restoring my 500b and i replaced all electrolytics. it was a big job, but doable. i measured each can and then looked at the size specs at Mouser for each cap, i found ones that could fit inside each can (one can has four caps). of course you could just put the parts inside the chassis but i think that would be pretty messy.
 
You might want to try replacing the 200 uF can first...that cured the sound problem on my 500c. 1N4007s are just fine, and they're cheap. On the coupling caps, I am not sure how the Vishay's will perform, but many folks are particular about those. I think many folks use Orange Drops (Mouser). I used Illinois and they are fine, although I would like to try some others. I also read a thread where someone really liked the Auricaps, although those are pricey.
 
Thanks for the replies.

ALBQ: C80, C83 which are the molded caps I referred to, are connected to the chassis. I’ll replace these but I’m too ignorant to know with what. Orange Drops ? For less than $1 I can buy those.

Chad Hauris: Regarding replacement of the molded caps. Orange Drops are cheap and meet the specs. Good enough? I’ll look into the JJ cans.

mhardy6647 : thanks for your efforts with the pictures and explanations. It was the first thread I read on the rehab process.

ampedup : Your experience with dealing with the multi-section caps would be invaluable. In the 400, there is a 20/40/40/40uF multicap which specs 300v/400v/450v/500v. Who makes something like that? JJ?

IthinkIcanfixit : The 200uf cap is definitely on the list for replacement. On the 400, it’s a black cardboard covered can that sits in plain view on top of the chassis. I’d like to gut it and put the new 200uf cap inside the old one.

I think the Orange Drop caps are made by Vishay and rebadged by others. I don’t see anything special about them other than they are good caps for a good price when sourced by Mouser . My ears probably can’t tell the difference one way or the other but I thought I’d give the MKPs a try. They seem to work good in tweeter x-overs.

Jon
 
Fisher 400 restoration

Jon,
Orange drops will work well in the Fisher - they also make for a decent sounding coupling cap. If at some point you feel the need to upgrade further, can always change the coupling caps to something more upscale - auri, hovland, kimber, pio, etc... As a starting point, I would recommend orange drops because they are 1) well made and very robust 2) generally fit the sonic character of vintage tube receivers and 3) reasonable cost. As an FYI, I used orange drops in my Fisher rebuild
Best of luck -ALBQ
 
I've used OD's in my Fisher 400 and Scott 340B, they do sound very good and retain the voicing of the units. The underchassi paper covered can is a candidate for replacement. Since it is out of view there is no need to try replicating the look of an exposed can. I've replaced all underchassi lytics and most of the mylars on my 400, the remaining cans are still good but I'm going to start replacing one can at a time with a new close equivelent and mount a conventional cap below to make up for any missing sections. These are beautiful sounding receivers.
 
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