Fisher tube chassis balance controls

audmod01

Super Member
I have a Fisher X-101-C coming from an on-line purchase. It will need extensive restoration, as a prior owner removed the volume control, balance control, mode switch and removed numerous audio cables internally etc. and used it as just an audio output amplifier. I intend to restore full functionality to the unit.

I have a replacement Fisher volume only control with loudness taps coming from a separate purchase. It has no on-off switch on it, but I can deal with that by using a separate switch on the back of the unit.

In adding the missing balance control, do any of you know whether the balance controls Fisher used was a linear taper control or an audio taper type?

For missing knobs I assume I will have to search various on-line sources until I find what I will need.

Any thoughts?

Joe
 
The balance control is a linear taper unit.

Good luck with your project. No doubt it is doable, but it sounds like it will definitely take some time, and may even include buying a beater to get some of the parts you need. The power switch is available from Mark Oppat if you want to get one.

I hope this helps!

Dave
 
Parts Sourcing for X-101-C Restoration

Dave;

Thanks for the encouragement. I have done similar things in the past. One that approached this was a Dynakit PAS-2 which had been changed to just a magnetic preamp. I did manage to gather up parts to put it back to original functionality. See:
http://s1213.photobucket.com/user/rubal182jhn/library/Dynakit PAS-2?sort=6&page=1
I guess I am a glutton for punishment.
Joe

Since this was originally posted, I have deleted my photobucket site due to their changes in rules.
 
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Very nice work Joe. Your main problem will be that the Fisher parts are not nearly so abundant as the Dyna pieces are, so it will just take more time.

By the way, welcome to the AK Fisher group!

Dave
 
Dave;
Thank you for the compliments. I also have a Fisher transistorized receiver model 500 with Tune-O-Matic (varactor tuning) currently serving in our HD theater system. My other stereo equipment is Dynaco PAS-3X, FM-3, FM-5, ST-70 and Garrard AT-90, two Kenwood KT-7500 tuners. One of my other projects was a Philco 40-201, a 1940 floor console AM/SW radio with electrostatically shielded AM antenna that rotates.

Those non-polarized AC sockets for the rear accessory items are virtually unobtanium now. I got the last few from DynakitParts.com for the PAS-2 I restored. The owner of the business was saving the rest for his personal equipment. The problem with those sockets was that too many people mistakenly tried to plug polarized AC plugs into them, thus cracking the surrounding plastic material of the socket. It is sad that people do not look carefully at what they are trying to mate together.
Joe
 
You're in good company here. There are a number of folks on the forum here with some really pristine equipment that they've restored very well. There's plenty here at AK on Dynaco as well. While this is the Fisher forum here, with your dual interest in Fisher and Dynaco (a number of us have multiple brand collections), here's a couple of threads you might find interesting:

http://www.audiokarma.org/forums/showthread.php?t=582379

http://www.audiokarma.org/forums/showthread.php?t=578485

Good luck with your X-101C, and keep us posted on your progress!

Dave
 
Some Pictures of the X-101C

Here are a few pictures of the X-101C. It is rather sad as a starting point. I have made some progress. Much time has been spent cleaning the chassis top. Underneath will be another matter altogether. It had been a roach motel for quite some time with corresponding corrosion top and bottom. Many audio cables were cut and will have to be replaced. The input/output RCA jacks are quite corroded and may have to be removed to clean and be reinstalled. Much of the chassis lettering was gone to begin with and after some cleaning even more has disappeared. I may have to generate some custom decals to replace those.

I got a start on the modifications by adding the 25.2VAC transformer. Electrolytic capacitors in the power supply will have to be replaced. It appears that I will need to use clamp mount types as OEM twist-tab mount types are no longer available. Some parts are already on order. I have determined a type of rotary switch to replace the missing Mode switch. I located a Fisher 500K dual volume control (but without the switch). I can use one of the slide switch mounting positions that is to be deleted to handle AC power on-off function.

Joe
 

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Looks like you are off to a good start. :yes: I have a working balance control, tone controls and selector switch from a 500B. I don't know if they are the same values you need for the X-100C but shoot me a PM if you think they will work for you.
 
Wow, that's going to need a lot of tender loving care, take your time with it and
it will be great when you get done.

Tube
 
Some more pictures of the X-101C

I forgot to include the picture of the front panel after cleaning. Here it is along with a few others. The inside of the control panel cover shows the left half after cleaning and the right half still to be done. I used a combination of Q-tips and Weiman's metal polish and for some really stubborn spots employed my Dremel tool with a cone shaped rubber eraser like tip to work the Weiman's polish. I also used some Eagle Nevr-Dull polish after the work progressed more. It leaves a protective film behind. I will try to get some more pictures tomorrow to show the end result on the cover.

Joe
 

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Audmod -- There is a good selection of new manufacture conventional twist tab can caps available from Antique Electronic Supply. They run anywhere from about $35 to $38 each, but are a quality piece and work well in my experience.

A power switch for your volume control would likely be available from Mark Oppat.

Little by little!

Dave
 
Electrolytics for the X-101C

Dave;

I have been looking at Antique Electronics Supply in detail and they have some that will work, but they do not have the one with a 200uF @ 250V plus a 40uF @ 500V. They do have some clamp mount 220uF @ 350V caps that I can use for the other cap in the voltage doubler circuit and fortunately that cap comes with a plastic sleeve on it for insulation. I have one older electrolytic that I could rob the four twist-tabs from and make a working new electrolytic by disassembling it for the twist tabs and working it into the bottom of the OEM capacitor after opening up the can and removing the old elements & install new axial lead or radial lead caps inside. In any case I will look again in case I overlooked something in their list.

Where there is a will there is a way. I do want to get the unit to look as close to original as I can though.

The volume control I was able to find does not have the small open window on the back with the pawl that can trip the typical snap-on switch that can so easily be applied to many controls. I would have to also find a shaft with the trip pawl and the rear section resistor element cover with the window in it. I may eventually find another volume control which was made to accept the snap-on on-off switch.

Joe
 
Hi Joe -- You might consider what I did on a project I just finished up -- a full restore of an X-202B. I used two of the cans from AES that are 50 uF X 4 @ 350 volts each. I paralleled all four sections so that each can became 200 uF at 350 volts. Then I added a 47 uF at 500 volt discrete cap underneath for the 40 uF section of the one dual cap. It made for a nice neat installation which you can see in this thread here in post #86:

http://www.audiokarma.org/forums/showthread.php?t=603537&page=6

In the pic provided, you can see how all four sections are paralleled together, with the supplemental 47 uF cap mounted close to the low side voltage doubler can. This is the best approach I have come up with yet for recapping the power supply of these units, where space demands that the can caps remain active rather than for show. You can also have them specially made by Hayseed Hamfest, but the AES cans retain the closest possible look to the original build, which was a priority in this case. For the high side cap, the original cardboard cover fits right on to the new can as an exact fit. In post #88 of the same thread, the OP posted side by side comparison pics of the unit as built by Fisher, and the finished restoration, which shows how closely this approach follows the original build of the amplifier.

Just one more option to consider!

Dave
 
Sometimes you really have to scratch your head as to why people do certain things with gear. It would be so simple to make one of these just a power amp without removing a bunch of parts or wiring. Heck, a bit of thought would give you pre-out / main in connectors to allow easy use of the unit as a power amp, preamp, or integrated amp just by using the connectors in the right way.

Best of luck on the project. Personally I find the basket cases to be the most rewarding projects. A simple clean and re-cap just isn't the same level of reward as putting something back together from a highly "altered" state.
 
Replacing Power Supply Electrolytics

Dave and Gadget;

Thanks for the suggestions. I had not thought about paralleling multiple sections as you suggested. I think I will follow that route to do this repair. I should have thought of that since I did something similar in restoring my Dynaco ST-70 amplifier. I paralleled two sections each in an OEM type electrolytic and had also used Joe Curcio's stacked and equalized caps on either side of the choke. It made for substantially improved stand-by capacitance for the amp.

In the case of this particular amplifier, the capacitor with the paper sleeve had already been removed and tossed, so I don't have the sleeve to slip over a new cap for insulation. I might be able to find something to use as a substitute and make my own label to identify the value and voltage rating.

Today I plan to take the power transformer off the chassis again to repaint the end bells. I temporarily re-mounted it to see how the leads from the 25.2VAC Xfmr will dress toward the AC input wiring terminal strip. In this case the leads of the new transformer are a little short, so I will have to extend them to reach. I can take the end bells off of the output transformers too and repaint them as well, then remount. With warmer temperatures today the paint will dry more quickly. Temps will be in the 80s.

Need to get my order from Antique Electronic Supply submitted today.

Thanks guys!

Joe
 
Xfmrs painted & Remounted

Today I managed to remove the end bells of all the transformers and sanded the rust off of them. I took them to the barn for repainting early this morning. I first gave them a shot of some satin black spray paint I had on hand. I had to cover the part number on one of the output transformers as it was painted on with white paint. The OEM output transformer had the part number stamped into the metal. After the paint dried, I then sprayed them with a shot of some clear acrylic lacquer for a more glossy look.

After finishing mowing the yard and letting the paint and lacquer dry, I remounted the bells to the transformers and then painted the leaves with some black paint using a paint brush. Now the transformers look quite presentable. I placed the control top cover over the front of the chassis. It has many hours of cleaning and polishing work on it. Now it looks fairly presentable. I took some pictures from a few angles to show how it looks now.

Joe
 

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Replacement Balance Control Arrived

Today I received an order I had placed with Antique Electronic Supply. It included some 12AX7s, 4 slide switches, a 40uF@500VDC electrolytic with axial leads, four DPST slide switches and a dual 500K ohm linear taper balance control.

In looking at the balance control and the chassis I could see that I had to do some custom fitting. Some work done on the unit before I received it had removed the OEM balance control and the mounting hole was enlarged to fit an on-off toggle switch. The toggle switch shank OD was much larger than the OEM balance control and since the new replacement had a smaller metric shank than the OEM control there was a gaping hole the new control would wallow around in. I found a round flat-washer that was about the same size as the opening in the chassis panel and about the same thickness. I used a round 1/4 inch file to enlarge the hole in the washer until it would slip over the shank of the new control. Then I had to slightly enlarge the hole in the chassis panel (it was not fully round). Once I had the hole enlarged enough I was able to install the control and fasten it in place. It now fits snugly in place and does not move about.

The shaft of the new control is a little short, but not by much, so it may work OK. I think the Fisher knobs for this control had a 1/2 round shaft to accept the knob, so I will have to grind down part of the shaft to fit a Fisher knob. I need one of the Fisher knobs that looks like two concentric knobs, but is a single knob. Time to start searching ebay and other sites.

Looks like this unit will be virtually a custom unit after I get it restored! I ordered two of the 50uF 4-section can electrolytics rated at 350VDC from Antique Electronic Supply today. Thank you Dave for the suggestion of paralleling multiple sections to get the needed 200uF for each 1/2 of the voltage doubler circuit.

Now that is behind me, I may begin replacing some of the cut audio cables one by one. It will take many hours. There are so many of them cut. Fortunately both ends are still there and the cables are well color coded - hardly any two of them are the same color. That will make finding the from-to connection points easier. Thanks to Mr. Avery Fisher!

Joe
 
Unbelievable progress Joe! Your attention to detail will more than just bring this unit back to a functioning state -- it will be quite the looker too!

Dave
 
Dumb statement, but make sure you file the flat on the right side of the control. Last round shaft I converted to a D shaft, I filed it 180 out and had to flip the whole control over so the knob pointed the right way.
 
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