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PostPosted: Sun Jun 18, 2017 8:31 pm 
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Location: A-Tube-O-Coke, ON, CA
Well, time and space has come together and I'm finally getting around to restoring a Fisher 500C that I've had just sitting around here for the last few years. My brother-in law kindly yanked it out of a console and just gave it to me so after years of research I think I'm ready.
Significant points:
1. It currently works fine. Even the power switch. :D
2. Festoon bulbs missing. Going to try some DIY for it. Any ideas? :(
3. Two panel switches broken. One was previously replaced with a toggle switch. I think I can source suitable replacements but they're black plastic, not the original brown. :roll:
4. It's a later model, and the proper service manual is unobtainium so far. Still searching and hoping....... :oops:
5. Two knob brights missing. May find a way to DIY my own and take the others off and sell to finance this project. :wink:
6. I'm prepared to DIY my own power supply to replace the can caps and diodes. :P
7. Still has all original Fisher branded tubes, except for two 7591A's, but they're old stock GE and Sylvania that seem to be matched well with each other and the other two Fisher 7591A's. :?
8. Got a variac that I had to wire up and fuse myself, so that was a neat little project. :D
9. I know that there are folks who can supply resto-pacs, but I'm more of a "thrill of the chase" kind of guy, so does anyone know of anywhere in the GTA (bricks and mortar, preferable) that I might be able to source better quality caps and resistors :?:
10. This is a fixed bias system, so I'm planning on DIYing a manual biasing system. Doesn't look too difficult. :D
11. It's going to need a deep cleaning (pots, switches, chassis surfaces, etc.). Obviously some kind of deoxit and lube for the pots and switches, but for the cosmetics I want to avoid using exotic or otherwise hazardous materials. Maybe something like using a Dremel buffer head and try toothpaste or other household substances. Any thoughts :?:
12. I've already substituted the 7591 cathode short to ground with 10 ohm 1/4 W resistors and found out that the current there is at about 40 mA, so it looks like I'll have to bring that down if I want to eventually use the newer issues of 7591's. It means replacing the grid bias resistor with something a bit lower, but to keep the same time constant in the coupling to the phase inverter I'll have to replace the coupling cap with something of higher value. Does anyone see what the problem would be if I just put another cap in parallel? Would that mess up the time constant of the RC circuit in a bad way? I suppose that it wounder be an interesting and simple experiment. (Hence my desire to find a local source of quality over the counter caps.)
13. I'm aware that I'm not really staying true to the spirit of the whole 'restore to as original condition as possible' and some may even call what I'm planning is borderline sacrilege, but my goal is to get me a working receiver of quality that will last me for years.

I TOLD you that I've been studying........wish me luck!
:lol:

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PostPosted: Mon Jun 19, 2017 3:54 am 
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Location: Milton, ON, CA
Good luck! Love to hear your sonic impressions when completed especially ab'd against some more current offerings.


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PostPosted: Mon Jun 19, 2017 4:22 am 
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PostPosted: Mon Jun 19, 2017 8:42 am 
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Location: Guelph, ON, CA
So this service manual is out-of-date?

https://www.hifiengine.com/manual_libra ... 00-c.shtml


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PostPosted: Mon Jun 19, 2017 9:44 am 
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noway wrote:
So this service manual is out-of-date?

https://www.hifiengine.com/manual_libra ... 00-c.shtml


That service manual seems to be the last version available, but vast majority of the schematics should be the same with a few parts numbers updated. Thing is with this older gear is that they made lots of running changes as they went along, mostly pretty subtle, so they didn't bother printing new service manuals every time. They sort of expected the technicians of the day to know enough to be able to work around small changes rather than being quite literal. Like going from a 10% tolerance resistor to a 5% or a 1/4W to a 1/2W.

Restoring these old beasts can be a fun project, especially when you are forced to improvise a bit to replace obsolete parts. Doesn't mean you can get sloppy, but being creative does help a lot, especially if you are not fixated on doing a full 100 point restoration.


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PostPosted: Mon Jun 19, 2017 9:49 pm 
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noway wrote:
So this service manual is out-of-date?

https://www.hifiengine.com/manual_libra ... 00-c.shtml

If that's the S/N 30001-49999 SM, that's the only one available AFAIK. My S/N is 66645U, and there are quite a few changes, namely the Rf front end, Golden cascade, use of nuvistors, resistor/capacitor value changes, transformer supplier and construction, component vendors......who knows what else. I'very been using WhiteoutTM and doctoring the one I have as I find things.
Might not matter to Joe Solder-Iron (or Sgt Pepper for that matter :wink: ) but proper and current documentation is one thing I'm anal about.
There is evidence of a 30001-59999 S/M at another one of my haunts, but so far I've only seen a picture of the cover and everybody there did the whole "oooĆ²oooooooo" thing over it and wanted him to scan and upload it to their library but that was a month ago. I'm still waiting and i'm not going to nag him about it......but I'm pretty sure that if hifiengine had it, or a S/M that actually covered mine, it would also be available at my usual haunts. Maybe it would be worth registering there anyway. I think I did once, but my UN/PSWD can sprung a leak a long time ago........

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PostPosted: Mon Jun 19, 2017 10:16 pm 
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OBI56 wrote:
.........especially when you are forced to improvise a bit to replace obsolete parts..........being creative does help a lot, especially if you are not fixated on doing a full 100 point restoration.

Darn tootin'.
I have to consider "The new black plastic switches won't match the original brown bakelite knobs, so do I find a way to paint the switches brown, or do I paint the knobs black, or do I just find a colour that complements the champagne faceplate and do both?" (and the faceplate STAYS champagne, there will be no discussing changing that. Uh-uh.)
And I could emery cloth pennies flat, buff them to a mirror finish, seal with lacquer, and voila! 8 cents worth of knob brights! Cheaper and better looking than anything you could pick up at a Michaels store, eh?
Can't wait until it's time to consider making a cabinet it would be proud to call home....... :lol:

Decisions, decisions......... :cry:

-- 20 Jun 2017 06:30 --

Oh, I almost forgot.
A picture of my home away from home for the next several weekends!
Attachment:
_Z8A0609.jpg
_Z8A0609.jpg [ 742.33 KiB | Viewed 220 times ]

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PostPosted: Tue Jun 20, 2017 9:22 am 
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Location: GTA, ON, CA
Please keep us posted on your progress. Good luck!


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