Greetings from a new 500C owner...questions and photos inside

bayen

New Member
Greetings! I've been visiting for a few months now and figured it was time to say hello and ask a few questions. First off, I'd like to say that this site is outstanding...I'm constantly amazed by Audio Karma's knowledgeable members! I've been a member of another audio forum for years and a Fisher 500C discussion on the Steve Hoffman forum brought me here to Audio Karma. After reading about the Fishers performance...not to mention the love at first sight... I knew I needed to have my own Fisher 500C...my first piece of tube gear. After a bit of searching I found a real nice working Fisher that didn't set me back all that much. The previous owner used it as his main receiver until he purchased a new system. The on/off switch had been replaced at one point but other than that it's all original. The seller brought it up slowly on a variac and then used the unit for a few weeks to make sure all was fine. Since it had been used recently, I decided to try it for a few nights before servicing. Wow! I finally heard first hand how amazing Fisher tube gear sounds! I was a bit nervous using the unit without the safety mods I've read about on this site...I kept a close eye on the tubes and everything seemed to be in super working order. The only odd thing I noticed was that the left channel cut out for a few seconds. When this occurred I decided to stop using the receiver until I could have it serviced. I spent a few weeks reading and taking notes...still trying to decide what route to take...service the receiver myself or take it to a tech. Honestly, if I could find a recommended tech within driving distance I probably would have done so already. It took me an afternoon of phone calls just to find a place that could test the tubes...a 45 min. drive from home..I live 30 miles west of Philadelphia. So, here is my plan. I have a work area set up with lots of space and lots of light. I was going to purchase a Metalbone kit, a soldering station and order a schematic. I have a multi-tester and can build a "dim-bulb" tester. The can cap replacement sounds difficult though...do I need to do this immediately? My soldering experience is limited to some work I did for my father almost 30 years ago...not point to point but work on circuit boards. I guess I just need to open it up and take a look around and get started or find a tech that is close and can be trusted. Also, I've never had tubes tested before...should I find out what type of tester will be used before I take the tubes to be tested? Thanks, Bayen
 

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Hello Bayen,
Welcome to an exclusive club.
It appears that you have a beauty there and it's in a fine case.

Considering that this thing has been used for all these years, and has been brought back up and used recently, I wouldn't panic if I were you.

Left channel cuts out? Pull the amp out of the case (upside down, unscrew bolts, flip back up, slide forward) out of the case. Verify that the fuse is 3.2 amps or lower. Connect it back to speakers, turn it on and slightly rock the small signal tubes with the unit running. Put a finger on the top of the glass that points up (don't do that to the output 7591s, they get hot) and rock slowly back and forth in about a 15 degree arc. You may just have lost contact between a tube pin and socket. Turn it off if you see smoke, but don't worry about the smell of heated dust, old nicotine or other olfactory unpleasantness. The smell of heat is fine. The smell of overheating or burning is not good.

No need to panic. You've already heard it. Listen to it while your kit comes. Read . . . study . . . print out stuff for later. Order the kit now, not three months from now, if you plan to use it unrestored for a week or so. Enjoy it.

A metalbone kit is a great place to start. Consider that the stage 1 restoration. Replacing the power supply caps (can caps and leftover electrolytics) would be the stage 2 restoration.

Practice tinning some wire with the soldering iron and get the feel of it again. Solder flows toward heat. The good news is that there are no PC boards to overheat traces on. Get a multimeter also.

Don't let anyone rattle you with dire shouted text warnings in all caps with lots of extreme punctuation. Do heed advice about messing around in there with the power on and keeping one hand behind your back while you do it though.

You've entered a new world and we welcome you.
 
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Hello Audiodon, I'm glad to be here! Thanks for the tips...your post gave me the confidence to order the kit now and start workin' real soon. I'll plug the 500C in this weekend and try your suggestions if the left channel cuts out again. I'll post more photos when the kit arrives and I begin the mods. I'm sure I may have more questions in the meantime:D Thanks again
 
Audiodon would know better than I, but one channel cutting out might also be caused by a dirty contact in the selector or tape monitor switch, or possibly dirty volume or balance controls. I find stuff like that happening often on gear that's not been used regularly. Read the sticky (somewhere) about Deoxit.
 
You have a beautiful 500C! Nice Fisher labeled 7591s, hope those test good for ya. What does it have for small signal tubes? If they're Telefunkens, be aware that the touch of a finger can wipe out the labeling on the tubes.

Rebuild it yourself. Go slow, one part at a time. It's hard to screw up if you're patient and make good joints with your solder. There's loads of help in here if you get stuck or make a mistake.
 
Really nice. I bought a X-100-C not too long ago and love it. I have my eye on nice restored 500C complete with cabinet. I think I've caught the Fisher bug. At least it's tax refund time!
 
Thanks for all tips and advice. I had the unit running all afternoon yesterday with no problems. Sound is unbelievable! I listened to a variety of LP's..both mono and stereo. I waited for the receiver to warm up and listened to a copy of "Beatles For Sale"..first UK pressing. Holy cow...I always thought this LP sounded great but yesterday the Fisher took it to a new level. Guitar separation and tone...vocal separation, the harmonies...everything sounded amazing! I can only imagine what a speaker upgrade might accomplish..I'm running a pair of JBL Northridge E90's. I plan on listening to a few CD's tonight and try out the headphone jack. I ordered the Metalbone kit yesterday and will begin work when it arrives...I'll add some more photos. I plan on having the tubes tested next week if I can plan the trip. I've never had tubes tested before...what should I know before going? Are there any questions I should ask the person doing the test? Thanks
 
Audiodon would know better than I, but one channel cutting out might also be caused by a dirty contact in the selector or tape monitor switch, or possibly dirty volume or balance controls. I find stuff like that happening often on gear that's not been used regularly. Read the sticky (somewhere) about Deoxit.

Thanks JonL. I will read the sticky and plan on cleaning all contacts with Deoxit this weekend. When I received the unit I checked all the knobs and switches on the front panel and everything worked fine. Last night I wanted to use the headphone jack and was surprised to find that the speaker selector is no longer functioning properly. No mater what setting I place the selector on, music can be heard coming from my speakers attached to the "speaker 1" terminals. I received my Metalbone kit yesterday and plan on opening the receiver up this weekend to take my first look inside and will try deoxite on the selector switch, hopefully this will work. Does seem strange though that changing the selector has no affect...I think if nothing was heard on "speaker 2" or "headphones" I would find it easier to accept. Anyone else experience this problem? thanks.
 
You'd have to flip it over, pull off the bottom cover and check the switch wiring to diagnose any further. It should go to speaker pair A, Speaker pair B, A_B, headphones only. If not, the switch is hosed, the wiring's wrong or something downstream is not right.
 
You'd have to flip it over, pull off the bottom cover and check the switch wiring to diagnose any further. It should go to speaker pair A, Speaker pair B, A_B, headphones only. If not, the switch is hosed, the wiring's wrong or something downstream is not right.

OK, I'll have it apart this weekend and will check..hope it's not to bad. I'll let you know. Thanks for your help, Bayen
 
Unlikely as it sounds I have seen frozen rotary switches where the shaft has stripped the hole on the disc and the knob shaft will turn, but the disc with the contacts doesn't. ORthe metal contact sheet has sheered from the disc itself.

when you visually inspect the switch wiring, rotate the knob and watch for the contact disc to turn WITH the contact sheet attached.

Larry
 
Unlikely as it sounds I have seen frozen rotary switches where the shaft has stripped the hole on the disc and the knob shaft will turn, but the disc with the contacts doesn't. ORthe metal contact sheet has sheered from the disc itself.

when you visually inspect the switch wiring, rotate the knob and watch for the contact disc to turn WITH the contact sheet attached.

Larry

Thanks Larry, I'll check the contact disc this weekend.
 
Well, finally had the time to open the Fisher up and have my first look inside. I spent the weekend going over my Metalbone kit info...taking note and locating everything that needs to be replaced. Regarding the problem I was having with the speaker/headphone selector switch, I checked the areas Audiodon and Larry had suggested. The back side of the selector switch is inside a small metal box attached to the top of the chassis. I was able to shine a light inside the box and could see the knob shaft and disc spinning when turned. From below I could follow the wires from where they exit the chassis to the speaker and headphone connections, all looked fine. I'm assuming that the face plate will need to be removed in order to have a better look at the selector switch and wires that lead to the speakers and headphone jack? Thanks
 
Yes.
Pull the knobs off and undo the two bolts to remove the front panel. Use a socket on those skinny bolts so you don't scratch the faceplate. Maybe you should get some contact cleaner before doing that though. Then you can clean up all the switches at the same time.
 
Great, thanks Audiodon! I'll order the fader lube and take the faceplate off when the cleaner arrives. I'm hoping that all the selector switch needs is a good cleaning! I'll keep you posted, Bayen
 
Get non-lubricating stuff. Faderlube is a lubricant.

I have a can of Deoxit 5. I read a few threads on cleaners and although a few methods varied, I think I read a few that suggested using Faderlube after the Deoxit 5? I'm a bit confused regarding different cleaners...what they should do and shouldn't. If all that is needed is Deoxit 5..I guess I'm ready to clean but will read up on cleaning products first. thanks
 
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