Thanks a lot, merrylander! I appreciate everything.
Fisher 400 stereo troubleshoot
- Thread starter ebertsj
- Start date
Thanks a lot, merrylander! I appreciate everything.
I'm not sure what you mean by that. Mixing tube positions?
drewbolce
Audio Analyist
In the FM section the particular tube in a particular socket is important to preserve the alignment. You need to get each tube back in its original socket.
Really? I had no idea about that.
I used to mix up the tubes in my Fisher 500-c when I was a teen. I was getting that annoying ~400hz buzzing sound that will never go away.
I used to mix up the tubes in my Fisher 500-c when I was a teen. I was getting that annoying ~400hz buzzing sound that will never go away.
The middle row of 6AU6s are switched around for sure. Are you guys referring to the middle row of 6AU6 or a different tubes? I'm really new to anything tubed.
Thanks
V1 thru V5 or 6 depending on whether your serial is below or above 48001.
The TUNER TUBES. All the ones in the middle row starting from behind the tuner and having a transformer tower between or next to them. 6ab4, 6ha5, 6au6, 6ba6, 6hs6
Print the attachment out. All marked in RED STAY IN THEIR RESPECTIVE SOCKETS. the 12AX7's can be rotated around With the exception of V100, thru V102. Mark them in RED ALSO.
The TUNER TUBES. All the ones in the middle row starting from behind the tuner and having a transformer tower between or next to them. 6ab4, 6ha5, 6au6, 6ba6, 6hs6
Print the attachment out. All marked in RED STAY IN THEIR RESPECTIVE SOCKETS. the 12AX7's can be rotated around With the exception of V100, thru V102. Mark them in RED ALSO.
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V1 thru V5 or 6 depending on whether your serial is below or above 48001.
The TUNER TUBES. All the ones in the middle row starting from behind the tuner and having a transformer tower between or next to them. 6ab4, 6ha5, 6au6, 6ba6, 6hs6
Print the attachment out. All marked in RED STAY IN THEIR RESPECTIVE SOCKETS. the 12AX7's can be rotated around With the exception of V100, thru V102. Mark them in RED ALSO.
V4, V5, and the one to the right of that I have been moving around. Oops! Glad to know now though. The V5 socket is the one I am having trouble with. V4 seamed to be FM and it is the one that blew. The blown tube and the fact that I can't get any tube to glow in the V5 socket is the reason I've been switching them around.
check the heater voltages on pins 3&4 on V 3, v4,v5. You should get 6.3 or so either ac or dc, depending on how they are supplied. I can't remember which riht now. 6au6's won't glow all that much. U have to be right over the top and looking straight down thru the nipple on top.
If you have a V6 6AU6 then this is what you need to copy. What's the serial# of yours. If higher than 48001 then use this one, if lower use the 1st one. Same applies for V100,101,&102. mark them in Red also.
Larry
If you have a V6 6AU6 then this is what you need to copy. What's the serial# of yours. If higher than 48001 then use this one, if lower use the 1st one. Same applies for V100,101,&102. mark them in Red also.
Larry
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I found a very small flat head screwdriver with an insulated grip that I was able to reshape the socket female pin holder. The middle tube now glows, volume is much better, and FM works when the tube is switched. One tube, when placed in the FM socket, still generates no stereo. I think everything is going to be good once the replacement tube gets here. Thanks for all of the help! I love this place!
merrylander
AK Member
I would not be in a hurry to swap V12 or V13 as they have been balanced with two variable resistors located under the chassis.
scottdavis08
Active Member
I know nothing about restorations to audio. Anyway, my receiver was not cutting on. I removed the off/on knob, and untighted the flat nut on the switch, and then sprayed deoxit, working this off and on switch back and forth. Eureka!!! These units are very old and have to be hit with deoxit/electronic cleaner every now and then!
Attachments
Scottdavis08. Correct procedure for DeOxit is thru the slot in the pot casing where the wires attach. This gets the cleaner on the carbon tracks directly. Trying to shoot it thru the shaft bushing does nothing except maybe dislodge some hardened grease, if you're lucky.
Pull the bottom cover off. Locate the pots and switches, and give each a short shot of DeOxit (Some pots are dual so get both slots). Then exercise 30-50 times vigorously. You'll see the slide switches with the open ends. Give them a spritz also and work back and forth also. Let dry an hour or so before powering up.
Pull the bottom cover off. Locate the pots and switches, and give each a short shot of DeOxit (Some pots are dual so get both slots). Then exercise 30-50 times vigorously. You'll see the slide switches with the open ends. Give them a spritz also and work back and forth also. Let dry an hour or so before powering up.