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Sony STR-V5 Relay and Switches

Spenser

Spenser

Mostly Discrete
Subscriber
Just got a Sony STR-V5. First one of the series I've had. Love it. This unit went through a local shop for a checkup and to address an issue. Good guy I know who had it briefly took it there before passing it on. I'm told it had a channel that was cutting out.

The shop said "repaired function switch contacts." Who knows what that means. I haven't popped the hood yet to see if I can see their tracks. It looks like they cleaned it up nice inside from what I can observe through the vents. I'm told they said they checked voltages.

In any event it's not working right. The symptom is easy to describe. One of the channels sounds good. Boy does it have oomph galore. The other channel: the low-end frequencies are missing. The highs and mids are there and perhaps weak and sketchy. (EDIT: LATER IN THE THREAD YOU'LL SEE ACTUALLY BEGINNING TO THINK THE OTHER CHANNEL MIGHT BE THE CULPRIT -- TOO MUCH AND DISTORTED BASS).
 
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"Thin" sound without bass makes me think in some ground connection on that channel is missing. If the unit had problems with sound cutting out, it probably has problems with the soldering at the boards. It could be the source of both problems. If it were my unit, I'd check the soldering on every board with a mag. glass.
 
Spenser said:
One of the channels sounds good. Boy does it have oomph galore. The other channel: the low-end frequencies are missing.
Click to expand...
That same switch probably needs to be disassembled and cleaned properly.
 
OK. Good thinking messrs. Thanks. Great hearing from you. I'll set up a temporary bench in a corner of the garage and open 'er up.

(...I'm in the process of packing and moving.)
 
Gently tapping the protection relay housing with a plastic alignment tool -- makes one or the other or both channels cut out.

It's the left channel that's 'thin.' At no time is the left channel coming back 'full.'

In any event, likely a bad relay here. In my opinion should be replaced.
 
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Anyone know the replacement protection relay for the Sony STR-V5.

Sony 1-515-302-00

Same as for the others in the series I think. At least that's what I'm picking up from other threads.
 
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Below is NOT a picture of mine. I borrowed it from a model STR-V6 thread.

Mine has the same relay. Could a trusty MY4-02 DC24 Omron be good here. EDIT: IS NOT A DIRECT, DROP-IN REPLACEMENT. SEE POST #24.

What do you think of these potentiometers. Mine are like these except blue covers. Keep or replace.

See IC 501 there just south of the protection relay. I'm not sure what's in mine but the schematic says HA 12002 Protector, Relay, Muting Driver. Are these known reliable. I see on the schematic five capacitors in and around this circuit.



DSCN4982.jpg
 
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The relays can be cleaned or replaced, what is easier for you. Sometimes I feel "silly" cleaning a 40 years old relay to fit it back, but on the other hand, I can do that in one hour and have the unit running again without all the bothering of finding and buying a replacement. Cleaning a relay usually gives good results and last for very long. You need some experience to determine if the contacts are still good.But if they look shiny after the cleaning, they are still good.

I'd face the "thin" sound issue before starting to replace components without a reason.

As mentioned, it sounds like a loose connection. I mentioned some ground connection, Avionic mentioned the function selector, it could be some soldering at that same selector, at the volume pot, wherever. You could jump the function selector soldering wires in one position, at least to discard a bad contact in that switch.

If the unit has muting transistors, they can be muting the signal. I can check the schematic later. If you have a link to the service manual, please post it here.
 
OK I'll pull the bottom plate and begin close visual inspection. Begin attempt to rule out mechanical cause.

#9892B2 head strap magnifiers work great.

If when going so far as to get the power amp boards free of the heat sinks -- which you have to do to get at the protection relay -- I think might as well also take care of any other additional freshening up (of the power amp sections), that would make sense.

It will be interesting to see how those contact points are mating and what the plating looks like.
 
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Equalizer and Tone amp boards looked good. Jumped the protection relay and the function switch.

Had thoughts of switching the channels over at the jumpers after R415/465 to isolate whether the perceived issue is before, or after.

However, playing with bass, treble, loudness and balance -- started thinking the left channel sounds as it should, and instead the RIGHT channel was the one misbehaving, exhibiting distortion in the form of muddled, booming mids and lows.

Then, with balance centered -- perhaps my ancient hearing and brain -- everything started sounding great. It's almost like the issue's a moving target.

I'm beginning to wonder about tone amp ICs HA1457(s). Ah well. Run with these and other things as is. See how the receiver does over some more extended run time.

LittleDiode appears to maybe have the OEM IC at twenty bucks a pop. Real or fake dunno. Loads of room for BrownDog adapters. Question would be what modern IC. What method of power supply mod if any. The HA1457s according to the schematic are running on around 22/21V.
 
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OK I moved and am starting to get my bench re-established.

Changed the title of this thread.

I've got the Sony STR V-5 cover off and am looking to get the heatsinks apart. I think it's the left channel power amp board that hosts the protection relay.

Anything else you would spruce up while it's apart? This receiver is only, what, 40 years old.
 
Nothing much to add here except to say I've got one of these that I'm setting up for my daughter's place. Mine works well but has had a consistent scratchy, sketchy volume control that would cause a channel to occasionally make ugly noise or sound scratchy. I had cleaned it about 3X and was thinking it needed to be replaced. Decided to give it 1 more cleaning, but this time, cleaned, blew it out, cleaned again and repeated once more and boom, it did the trick. Maybe some particulates were stuck in there.

I'm not a big receiver fan, too much packed in 1 place for my minimal diagnostic skills, but I gotta admit this bad boy has real punch and sounds quite nice. My daughter should be able to rock her place with this. Good luck.
 
Thanks Mike. Helpful to know. She is going to love it. Shake the walls? Oh yes. It will!

This was a channel cutting out as you know. I'm betting the tech took one look, saw where the relay lives, thought too much work here.

It's actually not that bad getting at the relay. You can see from the earlier picture how the whole heat sink block can be lifted out, flipped, and spread like a clam shell. It's even possible to detach the left channel power amp board and move it far enough to get at the relay pins without removing the output transistors.

When I got the old relay apart, I was surprised how lax its engineering. Same exact model relay as in the earlier picture of the V-6. Even with my craptastic photography you can see how the mating was poor and the plating is gone on two contacts.

Sony STR V-5 1.jpg

Sony STR v-5 2.jpg
 
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Thank you too Elnaldo. You had some good thinking. I'm going to replace this relay and run it some and see what she do.
 
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