Hi,

I have a Sony Ta-1055 integrated amplifier that recently stopped working. It was playing just fine, and then the sound cut out and now there is a crackling sound (without moving the volume sliders). After opening the unit, there is nothing obviously wrong with it (no visibly damaged capacitors, etc). I have the service manual, and powered the unit back on. It turns on ok, and when I tested the big capacitors in the power supply, they are showing 30v which the service manual says they should have. Fyi, the unit is all discrete components, mounted on a circuit board. What is the best way to figure out what's wrong? Thanks in advance.

Dave

 

First, does the crackling change if you tap it (not too hard, but give it a fright) or when you wiggle all the external cables - mains power, input, speaker wires?

Second, does the service manual include a schematic for it?

 

Does the crackling sound appears on one or both channels? If you turn the "Balance" control to one side, does the crackling sound disappear?

 

First, does the crackling change if you tap it (not too hard, but give it a fright) or when you wiggle all the external cables - mains power, input, speaker wires?

Second, does the service manual include a schematic for it?

Thanks for the response. This is my first post on the forum. I just powered on the unit again, and tried tapping it. Oddly enough, there was music before I started tapping. Nothing changed as I tapped either. The only thing that is connected to the unit right now is an rca to 3.5mm cable and an ipod. Nothing happened to the sound when I jiggled the cable either. The crackling is gone too. There is a schematic, block diagram, and parts list in the service manual. There were voltages on the schematic, so that's what I tested earlier. Not sure why the unit suddenly started working.

Dave

 

Something new just happened. The unit just went really quiet in one channel. There are separate volume sliders for left and right. There was a crackle, then the right channel went out (unless the volume is turned up all the way, then you can hear it a little bit). Now it just clicked back on to full volume. What could be happening?

Dave

 

I had a similar issue with a Sony. it was oxidation on the relay contacts. it's a very rare event.

You can TRY to power up the amp with sound input before it gets a chance to power up. Don't make it too loud.
You want the speaker protect relay to make contact when there is some actual current flowing (music), so the contacts get "cleaned". Do it a few times.

No promises.

 

I can definitely try that. Not sure if there are any relays in this unit though. Seems like if the relay is shut off there wouldn't be sound, regardless of volume, no? I can get some sound from the channel at max volume, but not at regular volume after the crackle. Is there a way to tell which side is right and what is left on the schematic? At least that way I can isolate troubleshooting to one side. The only thing I can see on the schematic is that one side has 100 series numbers, and the other has 200 series numbers. I'm uploading the schematic.

Dave

 

I think KISS is on to something. Get a can of spray contact cleaner. Spray the selector switch contacts and work the switches vigorously.

 

I think KISS is on to something. Get a can of spray contact cleaner. Spray the selector switch contacts and work the switches vigorously.

Meaning the input selector switches? Would I do that from the inside of the amp? Never done this before so any guidance would be appreciated. Would that help the volume sliders move more smoothly too?

Dave

 

Meaning the input selector switches? Would I do that from the inside of the amp? Never done this before so any guidance would be appreciated. Would that help the volume sliders move more smoothly too?

Dave

Yes, from inside. Do the switches first to see if it fixes the problem.
If the slides are hard to move, yes, contact cleaner will help.

If you cannot get contact cleaner in a hurry, I would get some isopropanol from the drug store and squirt it into the switch contacts with a syringe. Work the switches while the alcohol still hasn't evaporated.

 

It uses a fuse instead of a protection relay. Actuate the main/remote speaker switch a few times (at least 5 each) with and without sound.

 

This morning I cleaned all of the push buttons and volume/bass/treble sliders with 91% ipa. Just ran the amp for 40 min, and it sounds great! No crackling at all. Thanks everyone! One thing I do notice is a funny smell when the amp runs. Not an electronic kind of smell, but almost musty. What could cause that?

Dave

 

One thing I do notice is a funny smell when the amp runs. Not an electronic kind of smell, but almost musty. What could cause that?

Dead bugs, dust, roaches, cat hair for some ideas.

A sandwich was found in VCR.

 

Dead bugs, dust, roaches, cat hair for some ideas.

A sandwich was found in VCR.

lol. There's nothing like that in there, maybe a little dust. Should I just clean the board with IPA?

Dave

 

lol. There's nothing like that in there, maybe a little dust. Should I just clean the board with IPA?

Dave

House dust. Just use a soft paint brush and vacuum.

 

Turns out it wasn't very clean. I swabbed the board with a little IPA and some cotton swabs, which came back black. The smell is pretty much gone, but there is a residue. What can I use to clean that?

Dave

 

I personally like Methanol, but IPA should be just as good. They both won't attack plastics.

The only real way of removing IPA/methanol residue is to blow it dry quickly.

If it is grease, then soap and water on a small brush will work. Just stay away from sensitive components like variable inductors.

The usual cleaning process for semiconductor material was acetone (not for you - destroys plastics), Trichlorofloroethane and methanol with a dip and blow dry in methanol.

Trichor has been eliminated because of environmental issues. Here https://www.mcmaster.com/#electrical-cleaning-sprays/=1914h9a are some grease removal solvents.

tektronix used to wash their stuff in a dishwasher. I don;t recommend that either. See: http://ihnatko.com/2007/10/27/salvage-techniques-for-wet-electronics/ Transformers and water are a no no.

 

I used soap, water, and a sash tool (paint brush), after thorough rinsing, bake at 150 degrees f for a couple of hours. But that was in the vacuum tube days.