Found Sony STR-7800SD receiver after it went MIA for 27 years!!!

[Stevescivic]

What a great 're-homing' story!
And amazed it hadn't been 'ruined' in a damp basement.
Your dad sure had good 'taste' and I'm sure is pleased you fetched it back.
That older Sony stuff is very solidly built, I very nearly bought one of those, but couldn't afford it at the time...and what a pretty face, too!
My 'kids' have zero interest in any of the stuff I have - no idea what will become of it when 'the time comes' - hopefully many years from now.
Enjoy!!!

That’s a shame that they’re not into your hobbies. I always knew I would get into the same spouse irritating hobbies as my father. Since I was a kid at age 7 (yes I distinctly remembered playing with his hi-fi and cameras) that I knew growing up that I’d be the lucky child to be the one that followed in his footsteps and inherit his audio equipment. What is funny is that I scored a near complete Pioneer system from his younger brother who was into audio as well. Got myself a Pioneer SX-3800, matching timer unit and tape deck also all in pristine condition. So glad my other relatives don’t care for vintage gear - means more stuff to cram into my home

 

[Stevescivic]

That's in excellent condition, great you have her up and running. They are a very deep unit aren't they.

The 7800 is insanely huge. MUCH deeper than any Pioneer receivers I have owned or worked on. I swear the depth is as deep as Pioneer’s kingpin SX-1980 - too bad it doesn’t have the same WPC as the 1980

 

[Stevescivic]

Hifiengine has the owners manual, partial service manual and service supplement.
The service manual is missing schematics and board layouts but does have bias adjustment and the full parts list. The supplement would be helpful w/ changes.

Scans of the schematic in this AK thread.

Using the parts list, you should be able to determine if there are any known problematic semiconductors. (Search AK for lists of the problematic ones.)

thanks for sharing that link to the circuit diagrams. It will prove to be extremely handy when times come for me to re-cap the unit to increase it lifespan and possible improve on its already excellent sonic qualities. Elna Silmic IIs here I come

 

[50 Green]

You're welcome.
I used Silmic IIs in a recent recap of the Sony receiver I've had since 1973. It took a while for them to break in (harsh at first) but they sound great now: the warm sound Sonys are known for, but with a little more detail.

 

[Stevescivic]

Any suggestions to a reliable source of Elna Silmic IIs where the supplier will ship to Canada for a reasonable rate?

 

[50 Green]

Check w/ Mouser. They have them, but I'm not sure about shipping cost to Canadian addresses.

 

[Oldsansui441]

Any suggestions to a reliable source of Elna Silmic IIs where the supplier will ship to Canada for a reasonable rate?

https://www.partsconnexion.com/capacitors-ele-elna-rfs-silmic-ii-series.html

 

[Stevescivic]

https://www.partsconnexion.com/capacitors-ele-elna-rfs-silmic-ii-series.html

Excellent. Thanks.

 

[Blue Shadow]

Digikey ships for free if you send em a check. US and Canada. I add the local sales tax but that 6% is well less than the shipping on some orders from other suppliers.

 

[Oldsansui441]

Excellent. Thanks

Your welcome, Mouser also ships for free on orders over $60.00 AUD, guess it would be a similar figure for CAD.

 

[Stevescivic]

An interesting observation is that the receiver despite its age that after about three hours of play time that the sound signature seems to have shifted slightly and is now more airy and sounding like an amplifier that has been recapped. I am leery on how much more play time I get out of the original capacitors before it blows up but whatever Sony used in the receivers is certainly high quality because it’s sounds amazingly good. I would argue nearly as good as my recapped Pioneer receiver.

There is much debate on whether or not recapping improves sonic quality. I believe it does but depending on the state of the old caps. I know that some receivers I’ve worked on that had crackling noises and channels cutting out or had bad bass response that was fully resolved with a recap.

I know this Sony has seen very little usage in its life (honestly probably less than 300 hours) so I wonder if the lack of use has allowed the caps to not dry out as fast. Perhaps it is because these old caps probably had a ton of PCBs in them so they never dry out.

What would you folks suggest? The pots on this receiver barely have any crackling from oxidation and I know for a fact they have never been serviced. I was the first guy to break into the other day to use a blower to get 42 years of dust out of it; even then there was hardly any given its age.

My thinking is to plan is to do a recap of the power and protection board so the input voltages to downstream boards. Seems like an easy job since this receiver appears to have a good design layout.

What would you all do? Run it into the ground or do preventative maintence before damage actually occurs? Do Sony’s clearly show signs of imminent failure before things fry? Pioneers usually start crackling and cut out when it says “I need fixing” before things actually start blowing up.

 

[larryderouin]

Do a full recap in stages and when done, replace the 1050 for at least a while, if not permanently! The Sony is worthy of being set up as the Primary listening Rig, so give it a chance. Plus you can have your Dad over and the two of you can enjoy "his" rig once again. Do some Male Bonding!

electrolytics dry out whether used or not. And 40+ year old lytic's are usually beyond recommended service life.....ie; "you're skating on thin ice" or to put it another way, it's not a matter of if they blow-short-open, but WHEN they blow-short-open. The Main Filter caps would be the last thing I'd change as they have more liquid in them than the smaller caps. You can test them, if they are out of spec then change.

 

[Stevescivic]

Do a full recap in stages and when done, replace the 1050 for at least a while, if not permanently! The Sony is worthy of being set up as the Primary listening Rig, so give it a chance. Plus you can have your Dad over and the two of you can enjoy "his" rig once again. Do some Male Bonding!

electrolytics dry out whether used or not. And 40+ year old lytic's are usually beyond recommended service life.....ie; "you're skating on thin ice" or to put it another way, it's not a matter of if they blow-short-open, but WHEN they blow-short-open. The Main Filter caps would be the last thing I'd change as they have more liquid in them than the smaller caps. You can test them, if they are out of spec then change.

Definitely will plan to do a full recap on the Sony but I will likely plan carefully to do a full recap job in one shot (sans the tuner) so that it's finished once and for all so that I can get at least another 30 years out of it. Last night I gave the pots that I could access with a treatment of DeOxit and FaderLube so get rid of some of the scratchiness. Couldn't get to the volume control b/c the entire face has to come off to gain access to the two screws that hold the volume control bits together. I am curious as to how long I can go without doing anything before something fails. I hope it doesn't for a long time but as others have said that 40 years is a LONG time for things and are likely on the verge of failing. I do like the sound of the unit and I swear that it started sounding better as I kept it on and playing music. Maybe caps are "re-polarizing" after being discharged for so long. That being said, there is no hum or anything in the sound it the clarity is phenomenal. Replace the SX-1050? Hmm I dunno... I'm a Pioneer guy and that SX-1050 is a fully restored unit that sounds insanely good. Different sound signature for sure compared to the Sony but still extremely pleasing to the ears.

What is MESSED right up is today I managed by dumb luck to acquire an excellent example of a Pioneer SX-950 that is all original for a decent price from an electronics recycler. A broken tone switch and a tiny ding on the edge of the aluminum face but otherwise good. Kids helped me open that old unit up and clean up the insides and wash the aluminum face and knobs with a toothbrush to at least make it visually presentable in our home. I will probably recap that unit right away since I'm very familiar with the Pioneers and am confident in finishing the job in a matter of just a few evenings. Will probably flip or give first pick to a family member that likes stereos too. That SX-950 can't be turned on as I can clearly see the power filter caps bulging and ready to explode it's guts everywhere. No thanks - I don't need other things fried b/c curiosity got the best of me

Does anyone here have a BOM that I could start with for the STR-7800SD? Looking at the service manual there are a lot of highlighted capacitor part #'s where highlighted means "critical to replace with original Sony part #".

Given that Sony likely doesn't make any of these parts available anymore (despite they're just capacitors) I can only assume that I as long as I use exact or very close valued replacement caps that I should be fine.

I know that by looking on the boards that there are orange coloured capacitors which mean low leakage caps. Not having worked on Sony gear in the past I'm not sure what is the best way to proceed since their service manuals aren't as well laid out as the Pioneer ones are.

Thanks.

 

[restorer-john]

but I can’t help but worry that the electrolytics being 42+ years old will give out without a moments notice. It powers up flawlessly but is a poor predictor to figure reliability.

Don't worry about them failing, just enjoy it unmolested. There's way too much silly and uniformed scare-mongering on AK and the internet in general. The receivers of that era used primarily Rubycon small value electrolytics (blue sleeves) and they are very reliable and I can see them on the PCB.

You may need to check for brown glue corrosion however around the bases of the larger PCB mount ones.

I have several Sony amplifiers from that same series and they are completely untouched and test perfectly. Those Sonys are beautifully made.

As for the main filter caps, they will be fine.

Tell your Dad he bought an awesome receiver back in the day.

 

[Djcoolray]

Great experience....

 

[Oldsansui441]

I find small signal transistors are more problematic than caps in most units, where caps have failed it is often due to the use of that corrosive glue restorer john mentions.

I also don't think your Sony will have any troublesome transistors because firstly it is from the late 70's and secondly Sony usually used their own transistors and these seem much more reliable that what others were using, esp in the early to mid 70's gear.

I agree, if there is no bulging, leakage at bases evident or corrosive glue it will be fine. Can always recap down the road which will also likely improve sonics somewhat.

 

[spicer]

An interesting observation is that the receiver despite its age that after about three hours of play time that the sound signature seems to have shifted slightly and is now more airy and sounding like an amplifier that has been recapped. I am leery on how much more play time I get out of the original capacitors before it blows up but whatever Sony used in the receivers is certainly high quality because it’s sounds amazingly good. I would argue nearly as good as my recapped Pioneer receiver.

There is much debate on whether or not recapping improves sonic quality. I believe it does but depending on the state of the old caps. I know that some receivers I’ve worked on that had crackling noises and channels cutting out or had bad bass response that was fully resolved with a recap.

I know this Sony has seen very little usage in its life (honestly probably less than 300 hours) so I wonder if the lack of use has allowed the caps to not dry out as fast. Perhaps it is because these old caps probably had a ton of PCBs in them so they never dry out.

What would you folks suggest? The pots on this receiver barely have any crackling from oxidation and I know for a fact they have never been serviced. I was the first guy to break into the other day to use a blower to get 42 years of dust out of it; even then there was hardly any given its age.

My thinking is to plan is to do a recap of the power and protection board so the input voltages to downstream boards. Seems like an easy job since this receiver appears to have a good design layout.

What would you all do? Run it into the ground or do preventative maintence before damage actually occurs? Do Sony’s clearly show signs of imminent failure before things fry? Pioneers usually start crackling and cut out when it says “I need fixing” before things actually start blowing up.

That is a very nice Sony, maybe one of their best. If it were mine I wouldn't do anything to it besides make sure the area over the heatsinks of the output transistors are uniformly warm after it has been on a while... just kind of a crude idle current test. I have repaired many Sony receivers and amplifiers and they can be quite tricky. Unless you have much experience and feel absolutely competent repairing amplifiers, should something go wrong, I wouldn't touch it. Those units had no pattern failures like many other manufacturers sets... like open pass transistors or shorted zeners in the power supply. Just enjoy, it will probably work just fine for years.... and if something 'blows' at some time down the road, there's fuses inside for that, then you can go through it.

 

[Stevescivic]

That is a very nice Sony, maybe one of their best. If it were mine I wouldn't do anything to it besides make sure the area over the heatsinks of the output transistors are uniformly warm after it has been on a while... just kind of a crude idle current test. I have repaired many Sony receivers and amplifiers and they can be quite tricky. Unless you have much experience and feel absolutely competent repairing amplifiers, should something go wrong, I wouldn't touch it. Those units had no pattern failures like many other manufacturers sets... like open pass transistors or shorted zeners in the power supply. Just enjoy, it will probably work just fine for years.... and if something 'blows' at some time down the road, there's fuses inside for that, then you can go through it.

Yes it is insanely well built and weighs like a tank. What I find bizarre on this unit is the lack of pre-outs and pre-ins. For a unit of this caliber I would've expected it to have those. No biggie, I wouldn't use only a portion of the receiver. But isn't there a very real possibility that when a power supply goes that it will take out other parts of the receiver as well? I know in the Pioneer gear that when their equipment needs a recap that it usually makes itself very clear that it needs fixing. I am actually quite competent at taking things apart and rebuilding them. I've done several restorations already and am no stranger to reading circuit diagrams and soldering. I would personally prefer to not have to sink money into an otherwise fully functioning unit until absolutely necessary BUT I also don't want to risk frying this cherry condition unit.

BTW I have been paying attention to the heatsinks and I am pretty sure the idle current isn't even on them. The left side is slightly warmer than the right side.

 

[Stevescivic]

Don't worry about them failing, just enjoy it unmolested. There's way too much silly and uniformed scare-mongering on AK and the internet in general. The receivers of that era used primarily Rubycon small value electrolytics (blue sleeves) and they are very reliable and I can see them on the PCB.

You may need to check for brown glue corrosion however around the bases of the larger PCB mount ones.

I have several Sony amplifiers from that same series and they are completely untouched and test perfectly. Those Sonys are beautifully made.

As for the main filter caps, they will be fine.

Tell your Dad he bought an awesome receiver back in the day.

honestly the insides are immaculate. I took a leaf blower to it to clean out the dust. My air compressor in my garage has oil in the air stream and I'd rather not spray that junk all over a pristine unit. Looking over the unit it doesn't appear that there is any leakage or corrosion anywhere.

 

[Stevescivic]

I find small signal transistors are more problematic than caps in most units, where caps have failed it is often due to the use of that corrosive glue restorer john mentions.

I also don't think your Sony will have any troublesome transistors because firstly it is from the late 70's and secondly Sony usually used their own transistors and these seem much more reliable that what others were using, esp in the early to mid 70's gear.

I agree, if there is no bulging, leakage at bases evident or corrosive glue it will be fine. Can always recap down the road which will also likely improve sonics somewhat.

what is interesting is that for an old unit that is as old some of my other Pioneer gear that the Sony doesn't sound like it needs recapping. The sound is full and rich if not outright lush sounding. It has a slight warmth to it that I like a lot. Do I like it more than my Pioneer gear? Hard to say, it sounds slightly different but both Pioneer and Sony gear are pleasing to my ears.