Fisher Futura VI very low volume

T

Tlh082479

New Member
Hello, I am new to vintage audio. I recently purchased a Fisher Futura VI, I replaced all the recommended capacitors and it was working great. It really sounded amazing. I was listening to records tonight and all of a sudden it lost almost all volume. If you put your ear to the speaker you could hear faint audio. If you crank the volume the speakers make a loud repetitive banging noise.

Any ideas?
Thank you
Tom
 
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Does it do it with the unit in FM-AM-AUX- etc. The push buttons on the Futura VI are problematic in that they are ganged on a frame and very hard to disassemble for cleaning. They get dirty and bang, it don't work. It can be done, but takes the patience of 2 saints, Mother Teresa, and the DALI LAMA. I do mine bi-yearly, and it's a pain, but worth it for preventive maintenance. 1st thing to do is to pull the preamp, and douse the switches with DeOxit D-5 at all openings and let sit for an hour. After an hour, hit them again, ONLY THIS TIME, start exercising them like a typewriter (start one side and work to other, rinse, repeat 40-50 times). Finish up with a liberal spray of DeOxit F5 faderlube (or CRC2-26 Electronics Lube). Connect it all back up and let the faderlube dry about an hour. Then fire it up and test. If it works, GOOD. If NOT then we've got more work ahead.

Get a 3.5mm stereo jack to dual RCA Jacks for your phone. Disconnect the 59-T preamp on the console from the 59-A amplifier (RCA CABLES ONLY). Connect the patch cord from the phone, and set volume to all the way down. Turn on the Futura and wait 30 seconds. open a music app on the phone and advance the volume and see what happens. (You are determining if problem is in the Tuner/preamp or the amplifier itself). If it works, the problem is in the tuner, if not the problem is in the amp.

Check all tubes on a tester. Dirty tube pins and or sockets for the tubes can cause this. The most likely tubes in the VI that cause this are the 12ax7's on the preamp(3) and the 12ax7 and ELL80 tubes on the amplifier. For FM /AM the 6AQ8 and 6be6 are the main culprits but the 6GK5, 6ba6 or 6AU6 can do this too. CLEAN PINS with DeOxit D5 and a Toothbrush, and the sockets with DeOxit and a Dental brush for braces (interdental brushes) You can get them at any drugstore. Get a small set of picks and tighten up the tube socket leaves. I have most of my problems on the Futura VI from the preamp /tuner tubes.
 
Thank you for your response, I really appreciate it

The issue occurs on the radio both AM, FM and with a record, I do not have anything hooked up to the aux.

A couple of other notes:
#1 I did not replace the mylar capacitors on the amplifier - should I?

#2 I am not sure if this will help with the diagnostic but the issue occurred while in operation, I was listening to a record and the volume just started to fade to nothing as if the song was over.

I will attempt to isolate the problem with my phone and to work on cleaning all the switches and tube pins/sockets later this afternoon and report back.

Hopefully, that resolves the problem, because I do not have a tube tester and even if I did have one, I am totally clueless on how to use it. So I would rather not go down that road if I don't have to.

Thanks Again
Tom
 
What is your level of expertise because it sounds like it is going to be a little more in depth than just basic cleaning and tube testing.
 
I am very much a novice

My plan is to try the basics that larryderouin suggested and then go from there. possibly replace the mylar capacitors.
 
Fade out like it turned down volume most likely one or more of the 12ax7 on the top row of tubes or the 12ax7 predriver on the amp. the two 12ax7 on the left top of tuner/preamp are the phono tubes, 2 on the right are preamp tubes. Turn it on, set to FM, Volume at 1. Go in the back and wiggle the tubes in a circular motion (about 1/2" diam circle). Use tip of finger on the nib on top of the tube. Then go to the amp and wiggle the 12ax7 pre-driver tube. Very well sounds like dirty contacts. See if each one has a filament glow. Lack of glow indicates either a bad (open) filament, OR dirty contacts in the socket. Turn it on and look at each tube 1st. Wiggle each one with no glow 1st, see if it'll light up. if it does

You don't need to replace mylars on the 59-A, except the dark brown or black ones that look like "Dog-turds". These can go intermittent. But this sounds more like a dirty tube contact. BTDT with mine.

top of the preamp/tuner. the tubes you're concerned with are in the red circle.
59-t.jpg
 
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Thanks again for the update
I will thoroughly clean those tubes and sockets later today.amp.JPG

I did not replace the circled capacitors
 
I'm more worried about the gold colored lytics. They're absolute JUNK. Do those 1st., test, clean the tubes and sockets. Can you take a picture of the whole chassis?
CIRCLED in GREEN
59-tcaps.jpg
 
Good enough. But do the sockets and tubes 1st. the turds can wait. repair then restore.
 
Update, the first thing I did was hook my phone directly into the amplifier and it worked perfectly.
So the next thing I did was take the tuner out and clean all the tubes and sockets. I used deoxit along with a tooth brush for the tubes and a little Ortho brush for the sockets.
No luck

Strangely enough when I started it back up there was a humming noise. I noticed that when I unplugged one of the fusses it went away. That fuse was plugged into one of the transistors. I had some spare parts so I swapped out that set, and the hum went away. But the volume is still low unless it's coming from my phone.

Any other ideas?
Maybe clean all the transistors?
I might need to hire a professional.
 
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That MONSTER 12 pin connector on the amp that the preamp plugs into. Disconnect it and clean the preamp and amp side contacts with DeOxit. Wipe off excess let sit for an hour and then connect it. You will hear it snap in (lock). No snap in, you can lose filament power to V9-10-11-12 (Phono and preamp tubes). Make sure it's well seated and not cocked off to one side (why the hell didn't I think of this earlier!?!?!)

We now know that the amp is working, so concentrate on the preamp/tuner.

Check and verify here that all tubes are glowing. Do you have a tube tester or some way of testing the tubes? If not, Use your DMM set on ohms. probe pins 4 and 9, then 5 and 9, then 4and 5 on the 12ax7's. These are the filament pins for that particular tube type. Make sure that you have continuity between all points. 4 and 5 will be slightly higher as you're testing both filaments. NO FILAMENT GLOW, NO WORKING TUBE! You can probe the pins underneath the socket to check voltages too. Just make sure you've got a magnifier so you can verify the pin #'s. Pin 4 to pin 5. NOT to Chassis. All 4 are in series so you should see about 11 to 12vdc on each. Probe pin 11 and 12 on the connector. (this is either side of the tubes). You should get + 22 to 24vdc on pin 11 and -22 to -24vdc on pin 12

There is a little program out there called TDSL. www.duncanamps.com It's a tube database with pinout diagrams of most all tubes made, also has spec's and links to get spec sheets for the tubes. Handy for figuring out which is filament pins for all the tubes on the 59-A and 59-T. Once you verify that all of the tubes on the preamp are lit, then the next step.
ScreenHunter 339.jpg
Swap V9-V11 Test. If ok on that channel (phono will be kaput there), Swap V10-V12. If all ok now (except for phono), order a couple of 12ax7's. If not, and you're not comfortable working on it, send it out.
 
Thanks again for the reply when I was working on it, I did notice V12 and V13 lit up pretty well. surprisinglyV201 didn't seem to be lit up that much.
should I still clean the connectors? I guess it won't hurt

I have attached a video link of the problem, as you can see or hear the volume is very quiet and then when I turn it up the speakers make a sort of machine gun sound.

https://photos.app.goo.gl/pcyNtt8buX4e3PBT6


I do not have a tester but will do my best to try and troubleshoot them.
I don't even mind purchasing a couple just to troubleshoot, should I look on eBay for NOS or will any 12Ax7 work?
they are even sold on amazon - https://www.amazon.com/Matched-JJ-E...=1&keywords=Ecc83+12ax7&qid=1614785364&sr=8-9


I am just starting to think this problem is way out of my limited skill set on these machines. It's particularly frustrating because it was playing so well just a few days ago.

Thanks again for your help
 
I remember that before this issue arose the mute switch did not work.
After further research is it possible that transistor Q1 that is wired to the mute switch could cause this?Q.JPG
 
That's NOT tubes. That''s an oscillation commonly referred to as motorboating. Causes are myriad, but most likely in this case, capacitors.

Q1 is in the FM MUTING circuit. Doesn't affect Aux, tape mon., or phono.
 
Larry!!! I swapped V9 with V11 and it's working again!!! Thank you so much for your help! I can't tell you how much I appreciate it!

https://photos.app.goo.gl/56sszsn33SWD11NM8

I think the motorboating was caused by cranking up the volume.
So next step is some 12Ax7 tubes, any recommendations?
Thanks again, this has been driving me crazy
 
Just about anything that is a 12ax7 works well in the Futura VI. I use 12ax7LPS Sovteks in Phono, and have rotated 12ax7EH, JJ's (previous 2 Russian), RCA's, GE, Raytheon tubes but have settled on old stock Sylvania's. Cheap, sound good and haven't given any indication of poor performance. GE's would be my 2nd choice after the Sylvies.
 
I've seen things motorboat when the volume is not loud but as soon as you turn it up it starts to motorboat since the power supply is being more stressed.
 
I had a unit with a driver transformer where the phasing was backwards, making the feedback positive. It was quiet until reaching a certain signal threshold, then the motorboat took off.
 
It would only motorboat if the volume was past 9, but now that I have fixed the volume problem with the faulty tube, I doubt I will ever have it playing past 9. I kinda figured I won't worry about it. Is that correct or should I try and resolve it?
 
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