"Fixed" an amp that was in protection because of dust

gazman

Active Member
Found a RX-V870 at the tip, took it home, it went into protection mode as soon as it powered on. From web reading this sounded like bad transistors and a lot of work to fix, so I put it away. It was in pretty good condition though. No dings on the outside.

Fast forward a bit. Made a dim-bulb tester the other weekend, got the RX-V870 out as a 'known-bad' to test the tester. Have to admit I'd kind of dismissed it as BPC a bit - its 1990s, a lot of black. But its heavy.

Since it was there.... There was a lot of dust inside. Whole dust-mice. Blew them out, tried it again - and it worked. No protection mode. DC was a bit off - up toward 60mv on one channel, needed tweaking on the rest (three settings, one for the centre channel).

Ran it for a day, cleaned it properly, with some deoxit. It's running perfectly. Really nice amp. It's grunty. It has the 'amplified wire' Yamaha thing going on. Now I look, other people have said this too - I just hadn't thought to check. I'm really pleased - it's probably the best score I've had. For now I've got it in the kitchen, where a CA-610 usually is.

I can't believe someone threw out a reciever because it was dusty :)

The bulb behind the LCD panel is blown - but I think that was my cleaning, from memory it did work - so it isn't even that. Looks like they're a couple of bucks on the web.

And the preset ambience modes - Jazz Bar, Concert Hall and the rest - are absolutely *&@#$ awful. Have to be heard to believed - "Jazz Bar" kind of turns a solid mid-fi amp into a tinny ipod dock. It's really an achievement - like they let the apprentice design them, knowing no-one who bought "natural sound" would actually use them. The bad apprentice. The one they didn't let do gluing.

And it has this weird hole for a second transformer, it looks like. But from the manual, the top-end model doesn't have two transformers either - so it's just a hole. And the PCBs are blue. That doesn't look right, somehow.

But yeah, I was pleased. And unlike pretty much everything else, it shouldn't need recapping for another ten years. I can just use it!
 
Nice unit, I used to sell them and I have the almost identical RX-V850. I was pleasantly surprised to be reminded how good it sounds as a stereo receiver. The music DSP modes were awful on the receivers. The big DSP-A1000/2070 were a lot better in that respect as were the seperate decoders. One thing about the stock DSP modes, just like the brightness on TVs, they should be turned down to get a halfway natural result. Can't remember if the receivers have the effect level adjustment but if they do try turning it down until it is a subtle add on, not an echo heavy abomination.

The DSP-A1000 had a second tranformer, maybe the same boards were used. Could be as the L/C/R 80w amps appear to be the same.
 
One thing about the stock DSP modes, just like the brightness on TVs, they should be turned down to get a halfway natural result.

Yep - now you point it out, there's a 'Front Effect Level' control near those. I'll find it in the owners manual. Good to know, as I'd just turned it on to try, then written those modes off - I'll try winding them back and see what happens.

Thanks for that :)

Interesting on the DSP-A1000 too - that makes sense.

If anyone cares - the lamp spec is 14.5v 115ma 4.12mm dia (so T1 1/4). Some people are using 12v lamps - but other people are saying don't as they'll burn out too quickly. RS Components part 105-231 is 14v, 80ma, and looks about right for size. There's other threads around.
 
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The RX-V870 is a great receiver. Remotes for that line were easy to find at one time, in the obvious places. Much easier to operate with a remote.

I agree that the DSP modes are over the top - they were better with movies than music, back when the VCR was king. Today they're just useless.

The audio section of the RX-V870 is what makes it great. You're in for a treat. :thmbsp:
 
A remote is an interesting idea. Don't really think of them for vintage gear (this isn't, but you know...), but yeah, I could get a cheapie universal remote and run it with a CD player and this together and it would be like a modern setup. Nice idea - I hadn't thought of that!

And DSP better with movies, hey. Hmm, now I need a second TV, and then I can have a dedicated concert movie setup. I like it!

And yeah, it sounds really good. I'm happy. :music:
 
A remote is an interesting idea. Don't really think of them for vintage gear (this isn't, but you know...), but yeah, I could get a cheapie universal remote and run it with a CD player and this together and it would be like a modern setup. Nice idea - I hadn't thought of that!

And DSP better with movies, hey. Hmm, now I need a second TV, and then I can have a dedicated concert movie setup. I like it!

And yeah, it sounds really good. I'm happy. :music:

I'd go with a proper remote to unlock all of that receiver's features. You can adjust the DSP settings from your chair, for example, allowing you to dial it in from where it sounds best to you.

Just check the auction site for Yamaha RX-V receiver remotes - I have a couple of them and miraculously, they run all of my Yamaha gear, meaning that the codes must have stayed consistent throughout the years.
 
I have that same receiver, using it in the dining room. Picked it up for $20 at a thrift and found the remote at another thrift for $1. Everything works properly and it sounds terrific, one my best buys ever. You will like yours.
 
I'd go with a proper remote to unlock all of that receiver's features. You can adjust the DSP settings from your chair, for example, allowing you to dial it in from where it sounds best to you....
Cool, that sounds better. Thanks for that.

Okay, I admit it. I like fiddling with setup on universal remotes. You can move things, and make icons, and so much more.

But I'll keep it in check in this case :)
 
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I have that same receiver, using it in the dining room. Picked it up for $20 at a thrift and found the remote at another thrift for $1. Everything works properly and it sounds terrific, one my best buys ever. You will like yours.

I really do. Not sure of the way to say it, but it has more detail in quieter music, at a lower volume, than other amps. Sort of like a loudness function being on, or on automatically, but actually working properly - not just booming up the bass. Had it on for a while earlier and it's turning into a favourite very quickly.

I'm used to CA- and CR- era gear - I don't have any new Yamaha stuff, if this isn't too old count - this is the first, and it's really impressive.
 
Photos of the dust before cleaning. Forgot I'd taken them, and just found them on the camera :)
 

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They used a cool blue board in there. Yamaha's boards these days are a dark brown.
Can you take more? One thing I like, is they were built like a tank. My RX-V990 has a MASSIVE power transformer, and two 15,000µF 63V Filter caps. and 2 massive heatsinks.
 
Moral of the story: Clean your devices. I've been down that road too many times (usually on much higher voltage systems) and have seen contamination do a lot of damage.
 
They used a cool blue board in there. Yamaha's boards these days are a dark brown.
Can you take more? One thing I like, is they were built like a tank. My RX-V990 has a MASSIVE power transformer, and two 15,000µF 63V Filter caps. and 2 massive heatsinks.

I liked the colour too. Like fancy-colored caps - doesn't make any difference to anything, but seems like it ought to if the universe made sense :)

And should have take after photos - my bad! I'll take some when I open it to do the lamp.
 
Moral of the story: Clean your devices. I've been down that road too many times (usually on much higher voltage systems) and have seen contamination do a lot of damage.

I'm still a bit surprised by it all, really. Everything at the local tip is usually obvious why it's there - basically old, not working, battered. In fairness, maybe this was someone who wanted newer surround processing, replaced it, then it sat in a garage for years getting dusty - but protection being on, it just feels like someone thought it was bust and didn't try anything to fix it.
 
Photos of the dust before cleaning. Forgot I'd taken them, and just found them on the camera :)

Shoot! Thats hardly even dirty..Just a little dusty..
Heres a CR-2040 thats real dusty. I've seen a whole lot worst.
 

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Oh, I had a RX 870 as well, in protect mode too, except it was exceptionally clean, disconnecting the rear amp section got it out of protect, and then no sound came out, then the signal part on the rear had to be reconencted, I screwed up somethign and the whole thing now wont come out of protect.
Anyway its chassis and transformer and other parts will live a long live in one of my other projects.
Cool.
Srinath.
 
Shoot! Thats hardly even dirty..Just a little dusty..
Heres a CR-2040 thats real dusty. I've seen a whole lot worst.

You win. Of course, mine was broke cause of dust. Did yours still run?

And I found a dead spider inside another one. Does that count?

And also, thanks for all the posts in the past - you've helped me a lot without knowing it, back when I was lurking :)

srinath - I actually read your thread just before I cleaned it and was a bit horrified what I might need to do. I have to say, I was very relieved when it just powered on when clean. Shame about your one not turning out well. :(
 
Nope. Couple panel lamps and LED's light up.Thats about it. FM meters appears to be working.

Okay, you really win. Or at least, you and the ladybugs can fight it out :)

Lit lamps under all that dust kind of seems a fire risk, too, which makes yours worse ...

And another thanks too - I'm using your list of which cap brands and lines to pick - still can't find the actual thread, went looking for it just now for something in another thread, but I'm pretty sure the FM -> FC -> PW -> HE hierarchy came from you :)
 
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