My New Amp...

[meBob]

Hello all,

This is my new amp (Below), the Sony TA-F770ES.

I’ve read online it was a flagship about 1991 and seems to be very well regarded over in Deutschland, but not so well known over here. Most of my fact finding on this amp was done on their forums, with not very much info being over here.

The amp cosmetically is not mint, there’s scratches on the wooden sides, a couple on the volume knob and the control panel flap has been broken but repaired, the repair is a bit of a botch job that works rather well, so I’ve left it alone. There’s no dints anywhere.

Upon playing it, it was an instantly and obvious a big step up over anything I’ve owned before. Although, after a few hours of playing it the right channel began to fade out. After the feelings of rage and bitterness had subsided, I put my thinking cap on and had a look inside, there were no no bulging caps, no signs of leakages or anything to visually point to component failure. I turned my attention to the pots and absolutely soaked them all with evaporating/non residue contact cleaner while rotating the knobs (furiously!).

PROBLEM GONE!!!

I’ve since had a few 5 hour sessions with no problems.

While I was under the hood and with my multimeter handy I checked out the biasing. The left speaker output was reading 12mV and the right 8mV, they are now both reading a flat zero DC into the speakers. Those adjustment pots are ridiculously sensitive and fickle, eventually I got the job done.

The service manual for Idling recommended 35mV for both channels, they where both only a few mV out, now they’re both 35mV. Again, the adjustment pots same as above, I was ready to headbutt someone after I’d finished.

These adjustments I feel improved the sound, the bass seemed sharper and more of a stereo effect. I’d be interested if anyone else has also noticed an improvement also after biasing?

It’s an addictive listen with my KEF 103.2s.

The amp was bought for £195.

[Bigman80]

Hi Bob,

That's a fine unit you have there and should provide a very clean and transparent sound.

I had a 730ES and guess what.....it too kept dropping a channel. After all sorts of checks and tests and repeated failures, the selector switches at the board end were removed, cleaned, lubed and replaced. This eventually cured it's problems but I'd got so fed up with it I decided to move it on. The guy who bought it hasn't had a problem since.

Lovely amps and for that money, a veritable bargain.

Sent from my EVA-L09 using Tapatalk

[RobbieGong]

Yep! That right channel fade out / gone malarky is a proper PITA - I'm hoping mine will be sorted soon

[Bigman80]

I felt your pain brother!!!!!! Keep on keeping on. You'll get there

Sent from my EVA-L09 using Tapatalk

[meBob]

Hello Bigman80 & RobbieGong,

This fading of channels can be painful, especially when your amp is bought used and there's no warranty or return.

I've gotten away with it this time (fingers (and everything else) crossed).

A veritable bargain is exactly how I feel about this amp and I'm not even playing through a decent dac, it's going through a PC sound card.

Robbie have you tried what I did?

Switch the amp off and soak the pots with a decent contact cleaner while turning them, that's if they're not completely sealed?.