sony TA-F444ES noise on phono input

[mckennovitch]

sad sad sad.
though i'm very happy with the bargain TA-F444ES sony amp i hooked up with,
the MC phono input has some crazy radio noise / interference on the left channel.

a closer look and i notice the MM mode, though noise free has a weaker left channel output.

interestingly, the amp's volume knob can be used to squelch the radio interference.

my hope is that a simple cleaning of the switches (which are a bit scratchy i must admit) will clear up the problem. however, my guess is that there's something amiss on the EQ board.

gonna plunk this thing on the bench and have a look.
will start with DC offset and balance procedure as indicated in service manual,
then scan for anything obvious i guess.
i'd love to hear some tips and/or experiences with similar problems.

 

[cademan]

What kind of radio interference are you getting? Genuine RF interference is when you can hear a radio station in the background but can also be hum cause by bad cables. Are you hearing this or is it something else like white noise or hiss?

 

[mckennovitch]

well, i'm not sure if it's shortwave or FM or whatever, but there's voices. i guess it's a radio-station, couldn't quite identify language, not sure how local, but sounds more like a broadcaster than taxi, police, or airport. at the moment there's a slight beat-FQ which changes speed when swiping the volume knob. results depend on time of day.

 

[mckennovitch]

shoot. i reflowed some solder points on the eq board and presto: problem gone.
MC mode still has rather noticeable background hiss compared to MM... but then i guess that's just kind of normal due to the higher gain (?)
i still notice a tiny bit of distortion in the hiss of the left channel also, but i wonder if that's not due to cabling.. hmm. might just put this thing back together now and see how it performs.
did a bonus switch and pot cleaning and ... as i was dreading having to track dawn a replacement lamp for one of the function indicators ... i just flicked the dead lamp lightly with the power on, and it came back to life : )
less sad now.

 

[mckennovitch]

hmm. strange. i just tested the set up with an MC cartridge.
played 3 new random triftstore records.
2 of them are suddenly almost the best records i have in my collection.
does doing a bit of work for it make it sound better?
does beating an egg into the mix suddenly improve the taste?
perhaps it's the barometric pressure.
much less sad now. almost gleeful

 

[Goldie99]

I think the TA-F444ES uses a couple of (obsolete) rotary slide switches, which can be problematic vis a vis dirty contacts. Not sure whether they might be contributing to your issues, but they're well worth a decent clean anyway while you're in there.

 

[Binkman]

Soldering and resolder solves a crap load of diagnosis. Yes OP your mc circuit was picking up signal(s) and probably due to bad ground, mishandling etc.. or just old solder. Solder does age and I've even seen mold on solder joints because the factory sealer was omitted or just ignored.

Earth ground if you can drive in a ground rod or may check your outlets to assure they are up to date and house/ apt. grounds are safe, old houses rarely have the ground rod (if has one or street grounds) is dead 'earth' ground (can create ground loops to house grounds) Just noting your location in amsterdam don't know if your grounding between amp and phono might reflect. see how it goes.

 

[mckennovitch]

yes i cleaned those switches !
but i think the real culprit was old or cold solder on the big capacitor on the phono input eq board (you could hear it start to buzz when finger move close)

it's true i'm in an old building and yes, there's a whole history of weird stray voltages... i've recorded 80v electrical grounds and waterpipes 0.o
but last i checked everything was fine in that dept.
hmm. useful to revisit that question i think. thnks.

 

[SoCal Sam]

Looks like you have a handle on your MC issue so time for some fun! TA-F444ESII and CDP-520ESII with cover off getting new belts.

 

[mckennovitch]

there she is. note the out of wack dc balance on the left channel there.
right channel was +/- a couple of mV though

DSC05826

• mckennovitch
• Jun 2, 2017

and yeah, those weird sliding switches are really cool,
but indeed a bit of a pain to clean