From: hyc@hanauma.jpl.nasa.gov (Howard Chu)
Newsgroups: rec.audio
Subject: Sony STR-AV xx70 (was Re: AV Receiver Recommendations)
Date: 22 Jan 1993 11:11:52 GMT
Organization: SAR Systems Development & Processing, JPL
NNTP-Posting-Host: hanauma.jpl.nasa.gov

In article <1993Jan15.225421.22283@macc.wisc.edu> Peter Burke <pburke@macc.wisc.edu> writes:
>>>> I am interested in the comments/view of the netdom
>regarding the likes and
>>>> dislikes of the following equipment.  These models are
>the ones I have
>>>> been considering, but I am open to new ideas.

>>>> Yamaha RX-V1050, 850
>>>> Denon AVR1010?, 810?
>>>> Sony ES STR GX99, 69
>>>> Sony STR AV2090, 1090

>Well, all I have to say about this list is: stay away from
>the Sony 1090 - I have a 1070, which is about the worst
>piece of electronic junk ever sold in this country. I ahve
>a list of about 20 major problems (and I mean MAJOR -
>like? it turns itself on when i am not home, and happens
>to crank the motorized volume to max on its own.  Aren't
>those nice relays and computer chips fun?).  No clue what
>product is actually reliable and good, all i know is that
>if I can get my dealer to finally exchange the unit for a
>different brand, I'll be a lot happier than now.
>
>The Sony ES series is supposed to be a lot more reliable,
>but doesn't have any of the fund gadgets the STR-AV series
>offers.

I'd like to add a bit to this statement. I just took my 1070 back to the
local Sony Service Center this week, for the same problems mentioned above.
This is the second trip so far. The only good news is that the unit is
still in its original 2 year warranty.

I bought the service manual for the 1070, and one can immediately see at
least one source of problems - as most 1070 owners have probably already
noticed, the volume knob's motor generates noise on the spectrum analyzer
display. This is because there is only a single power supply driving both
the motor and the display electronics, *and* the CPU and all other associated
circuitry. There are some pretty decent transformers inside for the main
audio amp, but everything else runs off some puny little IC transformers.
In My Humble Opinion, the 1070 design is utter crap, and there's no way
that the model could ever perform without serious electrical problems.
There just isn't any isolation from the volume motor to any of the rest of
the control electronics. I'd guess that microprocessor itself is getting
a good burst of noise on its power as well. I don't have an oscilloscope
for monitoring, but even with a simple little voltmeter I was able to
observe non-trivial power fluctuations even when I wasn't making any
adjustments, using the remote, etc.

I would suggest that any/all current 1070 owners write a letter to the
Sony Customer Service department and complain loudly and bitterly about
this unit. (Assuming that you actually *are* encountering any troubles
with your unit. As far as I know, all the units in this series have the
obnoxious hiss in the surround channel, and looking at the schematics,
I can't imagine any unit not suffering from the same electrical problems
that I and so many others have already talked about.)

I wonder if we can force Sony to issue a recall and get 'em to replace
all of these things with something from the current xx90 series. It seems
that the 1090 doesn't have the hissing surround channel, at least. (At this
point though, I would not buy any new Sony audio equipment. At least my
XBR TV still works without trouble...)

It's possible that the ES series of receivers has a more intelligent
design, with independent power supplies for the microprocessor and associated
control circuitry, but I don't think anyone should *have* to pay a premium
just to get a workable design.

A lot of folks buy Sony stuff based on their name alone; I think Sony
deserves to feel a little heat over this issue. The xx70 series only sold
for just under a year before the xx90 series was released, so it seems to
me that the Sony engineers knew about the xx70 problems pretty early on.
-- 
  -- Howard Chu @ Jet Propulsion Laboratory, Pasadena, CA

There's a rough border between genius and insanity, but I'm a dual citizen.