Fisher 400 stereo troubleshoot

ebertsj

ebertsj

AK Subscriber
Subscriber
Hey folks. I recently bought a beautiful Fisher 400 off of barter town. Sounds fantastic! Tonight I sat down and turned on the fm stereo and nothing. Same with the fm mono. Phono still works fine. Any troubleshooting tips that somebody could help me out with? I'm a newbie so any advice would be helpful.

Thanks
 
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have you got a good antenna attached ? if so are there any mute switches or gain switches ?. if no antenna then i suggest you wire one in and it should fix it
 
petehall347 said:
have you got a good antenna attached ? if so are there any mute switches or gain switches ?. if no antenna then i suggest you wire one in and it should fix it
Click to expand...
Yeah, have an antenna. It has been working fine for the last couple weeks.
 
Let's start with the basics and a better symptom description.

Try flipping all of the switches and knobs in all positions with the unit off. Sometimes a dirty switch is the culprit.

Is the unit dead quiet in tuner positions? Is there any change in sound as you sweep the dial? Are there any clicks or pops when you switch from Stereo to mono?

How about your electronics skill level (none, some, expert)? Is the unit in a wood case? Do you have a digital camera?
 
Reseat your fm tuner tubes.... Don't bother with the multiplexer tubes for the moment...just the front end and IF stage tubes.....from the 6HA5 through the last 6AU6 (they are all kind of in a row)....essentially everything but the 7868's and 12AX7's. One of them might be in need of better contact. Make sure they're all lit.
 
drewbolce said:
Let's start with the basics and a better symptom description.

Try flipping all of the switches and knobs in all positions with the unit off. Sometimes a dirty switch is the culprit.

Is the unit dead quiet in tuner positions? Is there any change in sound as you sweep the dial? Are there any clicks or pops when you switch from Stereo to mono?

How about your electronics skill level (none, some, expert)? Is the unit in a wood case? Do you have a digital camera?
Click to expand...
I can hear a pop when sweeping the dial between stereo and phono. Not much much between stereo and mono. I tried flipping all of the switches. I feel I am somewhat knowledgeable about electronics but when it comes to this kind of stuff, I'm kind of lost.
 
1. Do you see a bluish glow at the sides of the eye tube when you switch to any of the FM positions?
2. Are all the tubes glowing?
Picture time.
 
I tried your guys suggestions and wiggled the tubes around. I now have FM! While I have the cabinet off I was checking things out. It seems that the 6AU6 tube, middle row, middle tube is not glowing. I switched a tube that I knew was glowing into that same slot and no glow. If I move a certain tube back to the left side where the FM seems to be, I get no FM.
Another question I have is that the volume seems to be fairly low. Is this normal with a vintage tube receiver? I've had the Fisher drive KEF 103.2s and Dynaco A-25s and the volume was about the same. I turn it all the way to the right, max volume, and I could definitely handle more volume if I was wanting to jam out!
Thanks for you're help.
 
ebertsj said:
Can a tube glow and still be bad?
Click to expand...

Yes, of course. But first you need to really clean the sockets.

You will need to get some DeOxit or CRC OD electronic cleaner and clean all of your sockets.

Spray them just a little in each pin hole and then spray down the tube pins with a paper towel behind them to catch the excess. Insert the tube and wiggle and pull up and down to clean. Examine each hole in the socket. If one is spread out so wide that it will not contact the pin you can push it closed again with a dental tool, small jewelers screwdriver or large sewing pin. Let it dry thoroughly before turning it on again.

Those tubes rarely fail, I'll bet this will fix it.

P.S. label your tubes for each socket. Most likely your volume problem is created by mixing tube positions.
 
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Most of the tubes that check 'bad' on my tester are glowing. Many tube problems are not obvious.....that's why there are tube testers. I usually check the connections & switches first, then check the tubes, then the sockets, then the components within the chassis that are hooked to the socket(s). There could be a bad solder joint at the tube's socket. I check it with magnification. Reflow the solder joint if you have a suspected bad one.
Be careful if you go inside the chassis. There are lethal voltages on those large capacitors. Make sure they're bled off before you go poking around the inside of your receiver. Check the stuff on top first. It may be something simple like a bad tube.
Also, has the receiver been recapped or is it original?

Larry D.
 
idadude said:
Most of the tubes that check 'bad' on my tester are glowing. Many tube problems are not obvious.....that's why there are tube testers. I usually check the connections & switches first, then check the tubes, then the sockets, then the components within the chassis that are hooked to the socket(s). There could be a bad solder joint at the tube's socket. I check it with magnification. Reflow the solder joint if you have a suspected bad one.
Be careful if you go inside the chassis. There are lethal voltages on those large capacitors. Make sure they're bled off before you go poking around the inside of your receiver. Check the stuff on top first. It may be something simple like a bad tube.
Also, has the receiver been recapped or is it original?

Larry D.
Click to expand...

Fortunately the Fisher has "bleeder" resistors which discharge the power supply caps when it is turned off. This is not a feature of all amps.
 
idadude said:
Most of the tubes that check 'bad' on my tester are glowing. Many tube problems are not obvious.....that's why there are tube testers. I usually check the connections & switches first, then check the tubes, then the sockets, then the components within the chassis that are hooked to the socket(s). There could be a bad solder joint at the tube's socket. I check it with magnification. Reflow the solder joint if you have a suspected bad one.
Be careful if you go inside the chassis. There are lethal voltages on those large capacitors. Make sure they're bled off before you go poking around the inside of your receiver. Check the stuff on top first. It may be something simple like a bad tube.
Also, has the receiver been recapped or is it original?

Larry D.
Click to expand...

It has been recapped. It's strange that the middle tube in the 6AU6 row won't light up. I bought this restored off of a highly respected AKer. I have no doubt in the restoration just can't figure that middle tube position. I can put my fingers on that tube and feel very little if no heat at all. Replace it with a known working tube an the same thing. I do know one of my tubes are bad though because the FM went out. It is firm when I put the tube in so I figured the connection was good.
 
drewbolce said:
Yes, of course. But first you need to really clean the sockets.

You will need to get some DeOxit or CRC OD electronic cleaner and clean all of your sockets.

Spray them just a little in each pin hole and then spray down the tube pins with a paper towel behind them to catch the excess. Insert the tube and wiggle and pull up and down to clean. Examine each hole in the socket. If one is spread out so wide that it will not contact the pin you can push it closed again with a dental tool, small jewelers screwdriver or large sewing pin. Let it dry thoroughly before turning it on again.

Those tubes rarely fail, I'll bet this will fix it.

P.S. label your tubes for each socket. Most likely your volume problem is created by mixing tube positions.
Click to expand...

Have you ever encounter the tube pin so dirty that the Deoxit would not suffice? I had that issue with my EICO HFT-90 when the front end tube was flaking out until I used Brasso to clean all the pins on the tube. I don't recommend using Brasso in sockets though.
 
ccheath said:
Have you ever encounter the tube pin so dirty that the Deoxit would not suffice? I had that issue with my EICO HFT-90 when the front end tube was flaking out until I used Brasso to clean all the pins on the tube. I don't recommend using Brasso in sockets though.
Click to expand...

I have found some that were so dirty they needed some scrubbing. I found a spray gun nozzle cleaning brush set at Harbor Freight that I use for scrubbing socket holes. I never use Brasso on tube pins or sockets. Anything with abrasives such as Brasso will remove the plating and lead to eventual socket or pin corrosion failure. The strongest thing I use is "Silver dip", this is a pink liquid which can remove all of the dirt and oxides and contains no abrasives.
 
Be thorough, don't assume anything.....

Use some magnification and check your tube pins and the sockets for oxidation/crud and connectivity. I've had one enlarged pin connector on a socket that felt as if it were tightly grabbing the pins, so its just good to be thorough and check through everything to find the cause of the problem.
 
I've restored units to the max, used them for a while and stuff still breaks.
I restored my lifetime keeper Fisher 500-C and used it for three years. Then it just kept getting softer and softer, though it still worked. It didn't sound right either.
I found that one of the new replacement power supply capacitors was not working right and when I replaced it, Voila!
It happens to all of us.
 
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