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Crawling back to my Fisher roots.

Ken Boyd

Ken Boyd

Super Member
Subscriber
Helllo everyone, my first tube amp was my Fisher KX100 that I purchased off a member here in Barter Town and a number of members here in this Fisher forum helped me with getting it recapped. I still have that unit, though I haven't used it in a number of years I still relish owning it. I have continued to buy a number of amps and preamps from other makers and some Fishers as well but I have yet to go thru the other Fishers that I have picked up. I think that is about to change as I want to restore a number of them in the up coming months. Of those are two X202b's, a 400 receiver, and a pair of 200A's which will be arriving this week.

I hope I won't be to much of a burden and while here who knows I might be able to help someone although I do have limits. :)
 
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Fisher sure made a crazy number of different models and types of gear.

(About that Fisher KX100 that hasn't been used in a number of years. I thought it was recommended practice to power up working tube gear every six months or so to keep the electrolytics formed?)
 
I have been under the hood of a few Fishers. The ones in bold are still around, X-101B KX90 FM100 FM200 FM200C Allegro A-19 Console ... 500C tube and IIRC TX100 500T solid state that all were recapped, freshened up servicing preformed.
Guess I must like them some.......

Fun times ahead just in time for a winter project for you.


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actuator said:
Fisher sure made a crazy number of different models and types of gear.

(About that Fisher KX100 that hasn't been used in a number of years. I thought it was recommended practice to power up working tube gear every six months or so to keep the electrolytics formed?)
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Actually being my first go around I didn't change out the electrolytics, and the amp worked great and sounded wonderful, but as I have learned those were important and not to long ago I ordered all new can caps from Hayseed so I should add that to the list. Plus I need to add the efb that will make it a better unit as well.
 
malden said:
what's "efb" ?
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What is EFB, guess this where you add Daves TM addition to the add what is he has trademark EFB. EFB was invented by Dave Gillespie and is his trademark. I believe it stands for Essential Feedback Bias, and it is a worthwhile addition to old Fisher receivers, and amps. And along with that I think a worthwhile modification is a addition to a resistor on a specific pin so that it acts to protect your transformers. I will do more digging when I get really into this to add the modifications to this thing.
 
Anyhow am rounding up the parts for this clean little X 202-b unit. I have secured a wood case, knob brights are on their way to clean up the unit. This unit is nice no corrosion or rust, looks all OEM inside, no one has been molesting it so I will be the first. :biggrin:.

I have a new quad of Mullards on their way, and are rounding up the rest of the tubes needed. I really don't like intergraded or receivers they sure are busy inside even makes my big Cary V12's look roomy.

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I wouldn't have purchased this other than the fact how clean it was, and cheap, I already have one of these that is nice and it has been on the back burner for years to go thru. I might run over to the storage unit and dig it out and do these as a pair not sure yet as I have a few other amps that I will be working on in between the time while I work on this. I would love to go thru the pair of Fisher 200 mono blocks, and I have a pair of Heath kit W6-M's that are sitting nearby already have purchased all the can caps and coupling caps to go thru them. I was just waiting on a thread in the tube section where they are going to go thru a pair and maybe make some recommendations to improve on the W6-m's My pair are real nice clean as a whistle and I want to do them right.

Anyway I have the bottom off this unit and am going to start getting inventory of the caps needed. I will make a project BOM so if anyone needs a list of the caps in the future I will have it for them if they are interested in what is all inside here.
 
“EFB” stands for Enhanced Fixed Bias, a modification developed by Dave G. He also developed a number of modifications related to the X-202-B that you’re about to restore. A worthy read:

dcgillespie

Thread 'Gilding the X-202B'

Following in the footsteps of previous efforts with my 400 receiver, an X-1000 and X-101C, this time it's an X-202B being presented for modernization. However, unlike those projects, this one also includes a full electrical refurbishment, with the thread being offered then simply as a record for referral for those with their own 202B projects.

First up is the laundry list of items addressed, to give some perspective to the work presented in the pics. Those items include:

1. A complete recap of all power supply and audio circuits.

2. Installation of an appropriate AC line current...
 
Creating a BOM for the list of capacitors needing replacing. A large number of them used in the unit are Mylar and Ceramic, just curious as to the opinion of others regarding replacing them. I was under the impression they don't age like electrolytic caps and should be ok. Am I incorrect on this. I could just do the electrolytic caps and then bring this up slowly in stages as far as voltage.
 
Something is different, looking at that one cap in the back the one with the cardboard wrap the one in your pic looks like a multi can cap while mine is just a single value.
This is a pic of what mine looks like you can see the diode here on mine, the OEM one which you recommend to change out to fast speed ones but mine cap is a single valvue, single terminal where the one on yours looks like a number of terminals I think three. I tried to screen shot yours but i was unable to get the file size small enough where AK would let me post it.
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Ok was able to copy the image on @dcgillespie unit, looks like a multican with four values in it.

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If I recall, Dave wired up several caps to make up the original value of the single cap at that location. In other words, unless you want to do the same, don’t worry about it.

Ceramics are virtually bulletproof. I’d be completely confident in leaving them alone. Mylars, well, it’s a maybe. If you don’t mind the cost and time investment, then by all means. Otherwise, you can leave them for part 2 of the restoration if it continues to bug you. Of course, as far as the can caps, I change them out no if ands or buts.
 
All electrolytics are coming out, also installing a CL80 for the input power. Figure on changing out the power cord to a three conductor, and then removing the safety cap. Would also like to install the EFB, just need to research where to buy them and how to install them. Most likely replace the wire wound resistors, I have seen them get brittle from heat over time, and I can change them with 5% over the 10% ones.
 
There is some debate on changing the power cord. I, for one, keep the original 2 prong plug as the unit was designed that way. The design anticipated an occasional hum being produced which was addressed in many a Fisher owner's manual with the instruction to flip the cord. That said, I don't think the Fisher products of the 50's and 60's posed the same risk as the earlier tubed radios. And those lived in wooden cases that separated the guts from curious hands. Cursory research on "three prong plug" or similar should bring up enough discussion to help you make a decision. Also, the "safety cap" in this unit doesn't appear in the official service documentation. In my own unit, I found the cap hidden somewhere but disconnected. I replaced it with a proper modern safety device and left well enough alone. (Larry D. and Audiodon (RIP) mentioned that it was an undocumented change.)

As far as the wire wounds are concerned: up the wattage to take care of over-dissipation issues as heat is what kills them.
 
Came across this old thread which I am adding here to make it easier to find while working on mine.

dcgillespie

Post in thread 'Adding DC Bias/Balance Test Points to the X-202'

Beyond developing EFB circuits for use in an existing design, installing it can be an exercise all unto itself -- particularly if it is to be a neat and orderly installation. The client who owned this beautiful X202 wanted the EFB modification installed, and since I ultimately wanted to develop it anyway for installation into my own unit, the timing of the request was perfect. So, the intention here is to show how it was installed, and what the benefits were as a result of the installation.

As has been shown in so many other installations, the application of EFB produces a number of...

But I have looked using the search tool above and have yet to find where to buy the EFB boards that I want to install. Anyone know where to get them?
 
Can caps ordered, going to do this project in small stages, can caps, and the other few electrolytics, safety cap removed and a new cord, and add the CL80, then power it up and give it a listen.
 
Dug out the KX200 my first tube amp project. It was in my storage unit and has not seen service for a few years. Had ordered and received all new can caps from Hayseed a while back now, figuring I better install them now and start bringing it up on the Vairac or they won't be any good.

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