I have a Sony STR-D390 receiver -- circa 1992, digital tuner, drives 2 pair
speakers, has remote -- that (1) produces no sound except a very slight
hiss/buzz at full volume, (2) does not display "stereo" on startup when in
tuner mode tuned to an FM-stereo station and (3) has a dead tiny red light
in its motorized volume control knob.

All these symptoms began as an intermittent annoyance a few months ago,
always curable with a light tap or two on the chassis, then not-so-light
taps, then a couple good whacks, then hitting on it so hard the "logical"
next step was a sledgehammer. Good thing I don't have one.

Disconnecting everything and taking off the cover and gently poking around
I can find nothing obviously wrong -- solder joints look OK, no loose
components or broken wires or loose connectors. Does anyone out there have
any insights as to what the most likely problems would be and what a fix
would involve?

I have an old multitester and there are repair manuals available on line
but my skill/knowledge level got maxed out when they used vacuum tubes you
could take out and test at Radio Shack. Repair by Sony at their flat rate
would cost almost as much as buying a newer unit, and I'm trying to gather
what info I can before deciding to take it in for repair locally or
replacing it.

Thanks in advance from southern Wisconsin.

In article , Bob wrote:

I have a Sony STR-D390 receiver -- circa 1992, digital tuner, drives 2 pair
speakers, has remote -- that (1) produces no sound except a very slight
hiss/buzz at full volume, (2) does not display "stereo" on startup when in
tuner mode tuned to an FM-stereo station and (3) has a dead tiny red light
in its motorized volume control knob.

All these symptoms began as an intermittent annoyance a few months ago,
always curable with a light tap or two on the chassis, then not-so-light
taps, then a couple good whacks, then hitting on it so hard the "logical"
next step was a sledgehammer. Good thing I don't have one.

Disconnecting everything and taking off the cover and gently poking around
I can find nothing obviously wrong -- solder joints look OK, no loose
components or broken wires or loose connectors. Does anyone out there have
any insights as to what the most likely problems would be and what a fix
would involve?

I have an old multitester and there are repair manuals available on line
but my skill/knowledge level got maxed out when they used vacuum tubes you
could take out and test at Radio Shack. Repair by Sony at their flat rate
would cost almost as much as buying a newer unit, and I'm trying to gather
what info I can before deciding to take it in for repair locally or
replacing it.

Thanks in advance from southern Wisconsin.

Look here, my good fellow from Wisconsin, spotting a cracked solder
joint often requires heaping quantities of magnification and lights
bright enough to toast marshmallows. Don't be tellin' me there's no
cracked joints if you haven't surveyed that thing at 10x on a high
rooftop at noon. Even then it's likely you'll have to wiggle suspicious
components to see the crack.

Smitty Two wrote:
In article , Bob wrote:

I have a Sony STR-D390 receiver -- circa 1992, digital tuner, drives 2 pair
speakers, has remote -- that (1) produces no sound except a very slight
hiss/buzz at full volume, (2) does not display "stereo" on startup when in
tuner mode tuned to an FM-stereo station and (3) has a dead tiny red light
in its motorized volume control knob.

All these symptoms began as an intermittent annoyance a few months ago,
always curable with a light tap or two on the chassis, then not-so-light
taps, then a couple good whacks, then hitting on it so hard the "logical"
next step was a sledgehammer. Good thing I don't have one.

Disconnecting everything and taking off the cover and gently poking around
I can find nothing obviously wrong -- solder joints look OK, no loose
components or broken wires or loose connectors. Does anyone out there have
any insights as to what the most likely problems would be and what a fix
would involve?

I have an old multitester and there are repair manuals available on line
but my skill/knowledge level got maxed out when they used vacuum tubes you
could take out and test at Radio Shack. Repair by Sony at their flat rate
would cost almost as much as buying a newer unit, and I'm trying to gather
what info I can before deciding to take it in for repair locally or
replacing it.

Thanks in advance from southern Wisconsin.

Look here, my good fellow from Wisconsin, spotting a cracked solder
joint often requires heaping quantities of magnification and lights
bright enough to toast marshmallows. Don't be tellin' me there's no
cracked joints if you haven't surveyed that thing at 10x on a high
rooftop at noon. Even then it's likely you'll have to wiggle suspicious
components to see the crack.
I agree...... You definitely have a bad solder joint. Check devices that
generate heat first. Sometimes you just have to resolder all joints to
find the faulty one.

Newfdog

For what it's worth...years ago when I was doing audio repair to get
through school, what we found an awful lot, was
mechanically-intermittent voltage regulator IC's. Usually they were
TO-220 case devices (if you're not familiar with that, it's basically a
3 pin package, having a rectangular heatsink with a smaller black
plastic housing containing the semiconductors) and they were usually
free standing on the board (i.e. not mounted to any heatsink.) These
were typically 9 or 12 volt regulators and for some reason, a large
amount of them developed intermittent problems. Sometimes we could
actually give them a light flick and they'd work, sometimes heat or
cold could affect them. Might be something to look for and
check...good luck.

In article , Bob wrote:



Thanks to all who replied. I think I found the problem: a 3-pin component
(transistor?) soldered to the main board and screwed to copper channel
(heat sink) that stands upright. Wiggling or tapping the unit makes the
whole gizmo click in and out. I guess the thing to do is re-solder it.

don't forget to use a little liquid flux.

Smitty Two wrote in
news
In article , Bob wrote:



Thanks to all who replied. I think I found the problem: a 3-pin
component (transistor?) soldered to the main board and screwed to
copper channel (heat sink) that stands upright. Wiggling or tapping
the unit makes the whole gizmo click in and out. I guess the thing
to do is re-solder it.

don't forget to use a little liquid flux.


It worked! I'm listening to it right now. Thanks again everyone.