Treasures found among Fisher tube era test equipment boxes

RS Steve

Tube Junkie
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I have been helping fellow AK member Tom B. go through all the original Fisher plant test equipment from the tube era days. I understand that Tom's friend owned the plant a some point after Fisher sold out. Tom found a 500-B and 400 receiver in boxes with all the test equipment, so I decided to restore the 400, and Tom the 500-B. I also grabbed a Bogen RF20 amp we found, and some other goodies. Glad we were able to rescue some items before the dumpster got them.

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Congrats on the save! -- but the 400 doesn't exactly look like it was a unit returned for warranty service.......

Dave
 
Congrats on the save! -- but the 400 doesn't exactly look like it was a unit returned for warranty service.......

Dave

It has all original Fisher tubes, maybe someone can determine the age of it, looks like an early serial number. Who knows what the story is on it though, I think it will clean up and the wood cabinet can be saved. I love the two keys they used as washers on the bottom.

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Steve; Your Serial is 15756E.
RS-Steves 400 Dataplate .jpg

As Fisher started the 400 @ a serial of 10001 your's is one of the 1st 6000 made and one of the, if not the earliest I've seen on AK. Made probably in spring of 1962 for the start of the 1963 model year (Sept 62). The only known to me freely available 10001-19999 manual is the one from HIFI-ENGINE, however it's missing the schematic for the main chassis. You could use the 20001 and up or 20001-29999 manuals, probably without problems. But look for any changes between the actual chassis and the schematics, and note them.

Get the #'s off the transformers. The date codes are on the 2nd line. Closest you can get is within 3-4 months of transformer manufacture which is close enough for gov't work .

Larry
 
Steve; Your Serial is 15756E.
View attachment 815251

As Fisher started the 400 @ a serial of 10001 your's is one of the 1st 6000 made and one of the, if not the earliest I've seen on AK. Made probably in spring of 1962 for the start of the 1963 model year (Sept 62). The only known to me freely available 10001-19999 manual is the one from HIFI-ENGINE, however it's missing the schematic for the main chassis. You could use the 20001 and up or 20001-29999 manuals, probably without problems. But look for any changes between the actual chassis and the schematics, and note them.

Get the #'s off the transformers. The date codes are on the 2nd line. Closest you can get is within 3-4 months of transformer manufacture which is close enough for gov't work .

Larry

Thanks Larry, cool to know it is a very early example.
 
9263702 breaks down to
926 = ToddElectric,Yonkers, New York
3702 = 37th week of 1962 week ending 15 sept.

Your's was probably built sometime between Oct 1st and Nov. 30. Just in time for xmas rush.
 
9263702 breaks down to
926 = ToddElectric,Yonkers, New York
3702 = 37th week of 1962 week ending 15 sept.

Your's was probably built sometime between Oct 1st and Nov. 30. Just in time for xmas rush.


Very cool Larry, thanks for posting that.
 
If anyone can locate two knobs that I need for this 400, please PM me with details.
 
Started to clean the grime off the 400, to my surprise it is pretty nice under all the dust. All tubes are Fisher except for the outputs which are Sylvania, soon I will test all of them before putting them back in.

I started going through the 5 large boxes of vacuum tubes I was able to grab, I found a few gems so far, a bunch of NOS 6CG7's and 6AU6's.

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I found time to test this early model 400 this morning, and it did things that I consider weird compared to others I have tested. On FM it showed a complete closing of the tuning tube bars, no output from the left channel, and the right channel had sound from the station tuned, but also a squeal that sounded like a flute. Needless to say I shut it down to assess things. I'm thinking I need to test the left opt for problems, all tubes lit nicely and the output tubes were all tested very strong.
 
Is the whistle in the tuner only, or in all sources. One channel or both? Check the transformer leads to the output tubes to make sure they weren't reversed. Swap the tubes left to right (one pair at a time) and test. Check your B+ voltages at the main filter caps to make sure they are ok. Check the output coupling caps and all of the usual suspects.
 
Kinda sounds like oscillation in the IF strip. I've had those exact symptoms before. Only would be present using the tuner if thats the case. Pulling any IF tube out would stop it too. Bad alignment problem has usually been what caused that for me, or a faulty component that was throwing off the alignment.
 
Kinda sounds like oscillation in the IF strip. I've had those exact symptoms before. Only would be present using the tuner if thats the case. Pulling any IF tube out would stop it too. Bad alignment problem has usually been what caused that for me, or a faulty component that was throwing off the alignment.


Yes, it only does it on the FM. But the left channel is dead as can be, no obvious easy fixes, I deoxed all the controls and got no improvement. Checking voltages is next up when I get time.

Is the whistle in the tuner only, or in all sources. One channel or both? Check the transformer leads to the output tubes to make sure they weren't reversed. Swap the tubes left to right (one pair at a time) and test. Check your B+ voltages at the main filter caps to make sure they are ok. Check the output coupling caps and all of the usual suspects.

Tuner only, left channel has no sound using any source, looks like this receiver is untouched underneath. I swapped in new nos inverter tubes, and it had no effect, I will try others next.
 
Is the whistle there on both FM MPX Stereo and FM Mono selector switch settings? If it goes away when FM Mono is selected, then the MPX sub-chassis is the culprit........

Dave
 
No signal from the left side on any source is a different problem. Sounds like time for some signal tracing with the scope. Should be easy enough to work out.

Does the 400 have the reverb connections? Something about those jumpers being pushed too far in killing the signal comes to mind.
 
I thought it was only when stereo was selected that I got the whistle, and I'll check the reverb jumpers when I get the unit back on the bench.
 
Hard to believe I walked away from this 400 back in early December, finally got back to it today and fixed the FM section. So all that's left to do to complete the restoration is can caps, rectifier, and diodes. Just proves walking away and coming back later with a clear mind can bring success. Turned out to need new capacitors in the tuner section.
 
This picture is low resolution. Hard to read the can in front, but it appears to have printed "119-63-15". If that's the case it would mean this tuner component from a third party supplier was stamped on the 15th week of 1963.

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