sony STR-AV310

[370forlife]

This was my grandpa's who passed away about 4 years ago, and he bought this about 5 years ago. Its a really nice receiver, I have it hooked up to two Polk audio 5JR 60469 speakers. It sounds really nice, extremely loud, no need to take it past 1/2 volume even though its only 90w (45 per channel), and those Polk monitors hardly distort. It has a remote with volume control and a volume knob, which doesn't make sense except for that when you turn up the volume on the remote it moves the knob. I also have a JBL 200w sub, but that's fed directly from my computer and gets its power from the wall.

The only problem I have with it is that sometimes there will be a buzzing from the speakers. I ruled out my computer, as it still does it when you unplug it, and the speakers are fine hooked up to anything else. I don't think it is the caps, as the primaries are Nichicon, and all the other caps are rubycons, I think it is some connection issue, as it sometimes goes away if you wiggle the input connections from the computer, and will always go away if you smack it lightly.

Any Ideas?

[Logistics]

cold/cracked solder joint? Replug some of those pin-connectors, too.

[370forlife]

I isolated the problem to a certain part.

Its labeled as the regulator on the PCB.

It has the markings as follows:

NEC
D1585
1 93

It has a small heatsink attached to it, and if you poke it with a screwdriver lightly, the buzzing starts. If you poke it some more, the sound completely goes away, and it starts to get very hot until you power down and re-power on the unit.

[PlainBill]

Originally Posted by 370forlife

I isolated the problem to a certain part.

Its labeled as the regulator on the PCB.

It has the markings as follows:

NEC
D1585
1 93

It has a small heatsink attached to it, and if you poke it with a screwdriver lightly, the buzzing starts. If you poke it some more, the sound completely goes away, and it starts to get very hot until you power down and re-power on the unit.

Maybe something like this?

Seriously, if resoldering it doesn't fix it, it's time to break out the scope and find out what is happening.

PlainBill

[shadow99]

You should start with checking the solder around that xsistor 1st. Be sure it's screwed tightly to it's heatsink. It may need to be replaced if all else fails.

You mentioned the speakers hardly distort. 45W is not alot of power and high volume levels will send it into clipping (distortion). Clipping is when a sine wave gets cut off and is square which is DC in that portion of the waveform. Thats how most speakers get cooked, by being fed distortion or clipping from an underpowered or overdriven amp. That's why you are less likely to blow speakers with a higher powered amp since it is less likely to be driven into clipping. All within reason of course.

Once the amp is driven into clipping, it heats up more, thermal runaway can take place on your outputs, clipping becomes worse, DC levels higher and before you know it the voice coils on your speakers are cooked and maybe your amp is fried.

Bottom line....dont turn it up so loud that it distorts. Unless you dont like your equipment. If you want cleaner, louder sound, buy a larger wattage amp. Your speakers will appreciate it.

[PM650]

That 2SD1585 is used as a +16V regulator from the main B+, for running analog ICs and other misc. circuitry.

[370forlife]

Well, I took out D1585, and when checking it with a DMM set on ohms, it does the following

left leg (positive lead of dmm)-center leg (negative) conducts about 17.85 Mohms and slowly drops down to about 17.10.

Right leg (positive lead of dmm)-center leg (negative) nothing

Nothing if I reverse the leads.

[370forlife]

according to NEC's datasheet for it, it is a 60v, 3A (5A pulse) NPN switching trasistor. Could I replace it with thise 400V, 5A (8A pulse) NPN switcher from a deer power supply I scrapped?

[370forlife]

Ok, so it worked.

Actually turned out that deer kind of overbuilt that power supply. It was a Sanyo 12A (20A pulse) part. Works fine now. Now extreme heat built up and no cutting out sound.

[weirdlookinguy]

Very nice.

I doubt that receiver is only 5 years old though. It looks early 90's. Exact same style as my old Sony AVR-900 (1989).

[370forlife]

Originally Posted by weirdlookinguy

Very nice.

I doubt that receiver is only 5 years old though. It looks early 90's. Exact same style as my old Sony AVR-900 (1989).

Well, bought it 5 years ago at a garage sale. I would imagine it would be from about 1990 or so.

[Robertt1971]

Hello 370ForLife,

I have exactly the same receiver as you (if you still use it), and also the same buzzing problem, for years i have been wiggling the connectors in the back to get rid of it for time to time, with mixed success. However this is a european version, bought originally in Holland.
I am very interested to know what type exactly you used for replacing the 2SD1585 (with the sanyo one), so i can cure this problem for good. Also quite recently the tuner stopped getting any signal and i suspect the Front End or the IF amplifier. Most likely a bad capacitor,transistor or resistor. I do have an osciloscope but it stops at 20 MHZ, so i do not know if his will be much good, furthermore i have the service manual of the STR-AV310, but no idea where to start trouble shooting the tuner, maybe you or someone else can put me in the right direction?

Kind regards from Cyprus, europe.

[370forlife]

I don't have this unit anymore, It began to buzz again after about 6 months of replacing that transistor. I can't remember the part number for the sanyo transistor I used, but it is very similar to a D13007/D13009. You can find them in just about any cheap computer power supply as the primary switching transistors. I got fed up with it and sent it in to goodwill. I got a 70's kenwood now that I use to crush cars on the weekend.

[RomoRock3r]

Hello Everyone, I also have this receiver and it had the buzzing problem too. I guess it was a manufacturer's defect. However I have an Issue, I think I fried mine . I would plug in my Sony Turntable to the PHONO jacks along with the ground wire to the ground screw and it would play well. Sometimes the buzzing would gradually get louder until it got so loud that the protection circuit goes on and an orange "P" would light up on the LCD. After I unplug the turntable, it goes back to normal. The last time I plugged it in, the buzzing got louder again until I heard a pop from the speakers. The receiver froze and it would not respond to the power button. Both the DBFB and Mute light was on and the LCD which said PHONO showed only parts of the letters lit. The "P" symbol didn't light. After a few seconds I saw a small amount of "Magic Smoke" coming from the receiver top. I quickly unplugged it after. I opened the top cover and looked for "fried" components. I didn't find any capacitors or resistors burnt or other burn marks on the PCB. The fuses near the transformer weren't blown. However I found the leads on what appears to be a Table Rectifier Diode burnt/charred. What I realized after is that the RCA plugs on the turntable seem to be frayed as when I plugged them into my computer, I also heard buzzing and crackling which was the same as I heard on the receiver before it broke. Is this receiver now completely broken? If I replace that table rectifier diode will it work again? I have found similar table rectifier diodes online however I am not sure what the original voltage and Amps were on the original piece.

Here is where the broken part is:


This is how the replacement part should look like:


Do I need to have the replacement diode have the same rating of Amps and Volts as the original?

[lti]

I don't think that the bridge rectifier is bad. You should start a new thread for your problem. This thread is about the bad transistor.