Fisher 674... issues

[drjohnnyfeva]

Recently purchased a Fisher 674 that was advertised as working. If trying to work counts as working, then... ok.

There's reduced sound in the left channel. I can hear it if I turn the balance to the left and amp the volume up to above 6. There's sound in the right, but it comes out very bassy and distorted when the volume hits 3 and it's worse above that.

I've followed the DeOxit protocol on here. Cleaned twice over a couple days with the regular and then Golded it today. Same issue.

The Loudness feature works. The High Cut works. Can't tell if the Mono or Tape Monitor do. Tape Monitor button cuts all sound as it should.

Started fiddling with it a little more today and found that the Phones work BUT... When not fully inserted, with some fiddling with the jack, sound comes thru as normal in both ears. Sounds awesome. All functions work. Pushed into the first click, right only. Pushed all the way in, left only.

The pots and buttons and speaker outputs were difficult to reach in this unit, but I know they are clean.

All testing was done with FM radio. I didn't test the other inputs. Any info or suggestions to resurrect this unit would be appreciated. I can't solder or read an electrical schematic. Sorry. This could be out of my pay grade.

 

[drjohnnyfeva]

Here are a couple pics. Looks in decent condition. I didn't see any hanging wires or broken connections, but I'm at the end of my usefulness without someone with some experience to give a pointer or two to look at.

 

[drjohnnyfeva]

No one? Anyone?

Looks like it's on it's way to the shop unless someone can give me something relatively easy to check. Both channels work in the headphones with some manipulation of the input jack...

Would love to track down something I could attempt without ruining chances of someone else on a pro fix.

 

[larryderouin]

Dirty Jack or cold solder joints on the jack. Deoxit on the plug and work it in and out. DeOxit all SWITCHES FRONT & BACK, ALL POTS (AGAIN). Some units more than others require repeat treatments to get them cleaned. Most of my FISHER Solid State units I have to do yearly cleanings, with initial cleaning 2-3 times before scratch, crackle, pop free.

 

[drjohnnyfeva]

I'll do it again and let you know. Can I ask another possibly stupid couple of questions???

There was a fuse missing when I got it. I replaced it with what was in the others, but I'm not certain it's the correct fuse. The first is a 2.5A - 250 V, the next 4 are 2A - 250V but the graphic on the back makes them looked bridged. My question is are the fuses for the front and rear speakers supposed to ADD up to the 2A -250V or are they the fuses that are required? The way it looks on the back is that there should be a 1A - 125V in each of the fuse tubes totaling 2A -250V. So there's the question... which fuse is required. I have the 2A - 250V in each of the remaining 4 after the power fuse.

The second question is, if the headphones work in both channels with manipulation - - - and it's before there's even a click. The tip is just in and if I turn it just right it goes into both ears just right. Sounds like a dirty movie scenario with my description, I know. So could a failed cleaning there at the Headphone jack cause the sound not coming out on the left as much as the right and the distortion on the right speaker?

There's definitely a degree of sticky residue on the insides. I just don't want to shoot DeOxit in places to cause a different problem.

Thanks Larry.

 

[drjohnnyfeva]

...oh, and one other thing... I did take out a burnt out lamp for the signal strength. And have not yet replaced it... The stereo sensor light is also out.

 

[larryderouin]

The HEADPHONES are BEFORE the SPEAKER SWITCH.

The Fuses F003 thru F006 come off the POWER SUPPLY and Feed / protect the individual amps from overloads. They aren't speaker protection fuses. Each one is 2A 250V

Doesn't make any difference with regard to the lamps. If the unit works, it'll work without lamps. Set the POWER-spkr swith to 2-CH, with speakers Connected to "FRONT MAIN (L & R). You can also (if you have 3 more pair) connect to REAR MAIN (L&R), FRONT REMOTE (L&R) & REAR REMOTE (L&R). Then with the volume down to keep switching noise down, Run thru each position (AFTER You've DeOxited them.) Exercise the switches aggressively.

https://www.hifiengine.com/manual_library/fisher/674.shtml for the manual.

As for the Sticky stuff, 91% Isopropyl alcohol and a box of Q-TIP's should take care of it.

 

[drjohnnyfeva]

Thanks again, Larry.

So I'm going to be aggressive to start on the headphone jack, is that correct? Test it all again after that before cleaning again?

When I did the two cleanings with the DeOxit, I was pretty aggressive both times thru. The knobs turn smoothly and there is virtually no resistance with the push buttons, just a smooth click. The sound after the first cleaning was better than what the first playing was out of the box. But there was no change with the second cleaning. Yet, I'll clean it again tomorrow, per your instructions.

And just so I understand what you're saying... the headphones come before any speaker function? So resolving the headphones could resolve the rest?

 

[larryderouin]

The headphones tap off the main line to the switch BEFORE the SWITCH. They are in Parallel, not series. If you have good sound in Headphones, but not the speakers, More than likely the switch is suspect. Even if it's smooth in operation, doesn't mean it's making contact. Take and look at the spring fingers as they make and break across the rotary wafer. You should see them raise and drop as they ride along the edge of the contact.

 

[drjohnnyfeva]

Well, cleaned it again. Same issues. I think it's beyond my level of know-how.

I observed what you said, Larry. There is a spot where is looks like a resistor is moving when the headphones are all the way inserted. It doesn't look correct to me. The piece that it is soldered to is one of the metal "feathers" from inside the phones jack. As you insert the jack to the first click, the "feather" moves and shifts the resistor. I don't even know if I'm calling the things by the correct names. It's just a jumble of stuff to me.

I cleaned the pots again, the terminals for components, the speaker connections for all channels, and the fuses I could find. All knobs turn freely and there's no debris on the q-tips after cleaning the terminals and inputs. I think it is shop bound at this point.

 

[larryderouin]

The resistor is supposed to be connected to the base of the "feather" where there is supposed to be a mounting lug for each "feather". It's possible that it is and it moves with the "feather." Not a problem as long as the solder joint holds. Once they go, you'll get intermittents.

See what a shop thinks.

This is the part of the schematic that pertains to the Phone's jack. The one for the rear is identical. See the Resistors one for each leaf? R003 &R004.