Hi,

I know this may be slightly off topic here, but there seem to be some
people around who are familliar with servicing 1970s audio equipment, so
I may as well ask.

I have recently had to diagnose a Yamaha CR-800 receiver. It was playing
perfectly, and then went dead on both channels. I have tested it, and
the power amp section is perfectly fine (thank god). Seeing as how both
channels went dead at the same time, I suspect it's a power supply
related problem, to do with the pre-amp section of the receiver. I
verified that the preamp section will not pass a signal from the aux
input, to the pre out, on either channel. Is there anywhere specific I
should look?

I didn't have any test equipment with me while I was looking at it
initially, so I didn't get any farther into it. Some of the circuit
boards are literally burried under the tuner section, and I can tell
this is going to be an ordeal to work on. All fuses check fine.

Any advice, before I dive in there? I can't believe just how many
electrolytics were stuffed into this unit - if I had to replace all of
them, it would be a nightmare. I really just want to get it working
again, as it sounds good, and the variable loudness control is a useful
feature, when listening at low levels.

Max

Just as a side note - why does this component have so many parts!? I can't imagine
an American made unit having so many parts, even if it performed the same
functions! There's just acres of transistors and electrolytics in this unit!

"Max Holubitsky" wrote in message
...
Just as a side note - why does this component have so many parts!? I can't
imagine
an American made unit having so many parts, even if it performed the same
functions! There's just acres of transistors and electrolytics in this
unit!

**There's a bunch of reasons:

* Back when your Yammie was built, (Japanese) labour was cheap. Putting lots
of functions on a product was cheap and guaranteed to win sales.
* Back when your Yammie was built, the local (Japanese) market craved lots
of features.
* There's nothing inherently wrong with using lots of components in an
amplifier, provided they are used sensibly.


--
Trevor Wilson
www.rageaudio.com.au

I guess I owe you a beer Trevor

The problem was a faulty preamp voltage regulator circuit. For some reason,
something in the phono eq board shorted, and blew the regulator circuit. I
didn't even bother testing it, since it's at the bottom of the receiver, and
nobody uses records with this unit anyway. I disconnected the phono board
completely, and put in a half wave rectifier and a C-R-C filter to supply
the preamp. It's not regulated, but it works well, and it's back in
service. Playing it right now actually. My parents should be happy to have
music again, and the search for a new amplifier (AMC or otherwise) is now
put off indefinitely. I didn't do board level repair, because I have no
schematic, and to get at the regulator board is nearly impossible.

I checked DC offset. Once channel is 47mV and the other is 103mV. Nothing
horrible, so I'll leave well enough alone.

This is one hell of a good sounding receiver. Thanks for the advice.

Max

"Max Holubitsky" wrote in message
. ca...




No loudness control variable or otherwise on the Yamaha RX-V630 which is
only one generation back from the latest edition RX-V640


Is this a stereo reveiver, or an A/V receiver? The Yamaha stereo receivers
at A&B Sound here in Edmonton all have the variable loudness. I didn't
even
check out the video models.

A/V

http://www.yamaha.com/yec/index1.htm