"Wayne Tiffany" wrote in message
. com...

"James Sweet" wrote in message
news:KxCxj.9172$xg6.8270@trnddc07...

That's just a standard 5V 3 terminal regulator. 78L05 should work, as
will a 7805 if you swap the pins around, or many other similar parts.

I'm certainly not the expert here, but the 78L05 is a 3 pin, 5 volt, 100
mA regulator. The L78LR05 that is on the board is a 5 pin, 5 volt, 150 mA
regulator. The other two pins are for a reset output and a delay
capacitor, and are most certainly connected.

I checked with our local Electronics Supply here in KC and they didn't
find it listed at all. More thoughts?

WT


Oh it's a 5 pin? Hmm that's odd, can you tell who made it? You might look at
Fairchild or National Semi's website, both companies offer free samples of
many parts.

"Wayne Tiffany" wrote in message
. com...

wrote in message
...
if u are equipt with voltohmmilliameter(vom) check first the presence of
B+ on the collector of ur HOT.if it is normal Bet 100-135 v and assuming
your PS works fine ,proceed to check the presence of hor. driving
voltage on the Base of the driver transistor, using the lowest ac range
of the tester but do not forget to insert the positive probe to the
output terminal of the vom (Im talking of a analog test er , usually it
has 3 terminals ) so that only the signal will be measured .because in
the output terminal of the tester there is a coupling capacitor that
blocks the dc potentials.connect the black probe to ground.locate the
cold ground and not line ground of the PSupp. if u measured a driving
voltage, atleast .05 or .09V put the probe this time at the collector
of the driver , notice the driving voltage is much stronger .it will
deflect the meter over its full scale.replace ur Hor output transistor,
thats culprit also the flyback must be check . good luck

What we have been chasing is that the B+ is not there, and there appears
to be no signal out of the micro. The why not is the current mystery.
Thanks for the thoughts.

WT


Sony's part number is 8-759-805-37. Any Sony distributor can get it; Andrews
Electronics number is 800-289-0300.


Mark Z.

"Mark D. Zacharias" wrote in message
. net...

Sony's part number is 8-759-805-37. Any Sony distributor can get it;
Andrews Electronics number is 800-289-0300.


Mark Z.

Well, that's the inexperience showing through. I didn't think to chase the
Sony part number. Thanks.

WT

"Wayne Tiffany" wrote in message
. com...

"Mark D. Zacharias" wrote in message
. net...

Sony's part number is 8-759-805-37. Any Sony distributor can get it;
Andrews Electronics number is 800-289-0300.


Mark Z.

Well, that's the inexperience showing through. I didn't think to chase
the Sony part number. Thanks.

WT
Found one and ordered. Next week when it arrives we'll see if it makes any
difference.

Something that keeps coming to mind is that the family has complained for
some time that if they hit the volume up or down button, the channel would
also change. I had thought it was maybe related to dirty switch contacts,
but now I'm not so sure. We also have another Sony set that is doing it
now. In both cases the remote would operate it just fine. So I'm sitting
here thinking that if this 5v regulator had been failing for some time,
could that affect that? And if so, is it failing on the other set??

WT

"Wayne Tiffany" wrote in message
. com...

"Wayne Tiffany" wrote in message
. com...

"Mark D. Zacharias" wrote in message
. net...

Sony's part number is 8-759-805-37. Any Sony distributor can get it;
Andrews Electronics number is 800-289-0300.


Mark Z.

Well, that's the inexperience showing through. I didn't think to chase
the Sony part number. Thanks.

WT
Found one and ordered. Next week when it arrives we'll see if it makes
any difference.

Something that keeps coming to mind is that the family has complained for
some time that if they hit the volume up or down button, the channel would
also change. I had thought it was maybe related to dirty switch contacts,
but now I'm not so sure. We also have another Sony set that is doing it
now. In both cases the remote would operate it just fine. So I'm sitting
here thinking that if this 5v regulator had been failing for some time,
could that affect that? And if so, is it failing on the other set??

WT



Front panel buttons are usually multiplexed, a bad connection on or to the
panel will cause weird things like this to happen. Glass cleaner dripped
down into the switches can cause it too.

"Wayne Tiffany" wrote in message
. com...

"Wayne Tiffany" wrote in message
. com...

"Mark D. Zacharias" wrote in message
. net...

Sony's part number is 8-759-805-37. Any Sony distributor can get it;
Andrews Electronics number is 800-289-0300.


Mark Z.

Well, that's the inexperience showing through. I didn't think to chase
the Sony part number. Thanks.

WT
Found one and ordered. Next week when it arrives we'll see if it makes
any difference.

Something that keeps coming to mind is that the family has complained for
some time that if they hit the volume up or down button, the channel would
also change. I had thought it was maybe related to dirty switch contacts,
but now I'm not so sure. We also have another Sony set that is doing it
now. In both cases the remote would operate it just fine. So I'm sitting
here thinking that if this 5v regulator had been failing for some time,
could that affect that? And if so, is it failing on the other set??

WT


Page 50 of the PDF (showing page 77 of the paper manual) shows that the
switches involved are part of a resistive ladder arrangement. Obviously, a
problem with the switches here will cause the stated symptom. I would look
no further than this, except perhaps for some contamination on the board or
switches themselves. We sometimes see this type of thing from people
squirting cleaner directly on the screen - it runs down into the switches.

Mark Z.

"Mark D. Zacharias" wrote in message
t...

Page 50 of the PDF (showing page 77 of the paper manual) shows that the
switches involved are part of a resistive ladder arrangement. Obviously, a
problem with the switches here will cause the stated symptom. I would look
no further than this, except perhaps for some contamination on the board
or switches themselves. We sometimes see this type of thing from people
squirting cleaner directly on the screen - it runs down into the switches.

Mark Z.

Did a little investigating this weekend and I think the problem with these
switches is in the switches. I measured the resistance to ground as I
pressed the switches and they all wander all over the place depending on how
you press them. I'm surprised they work at all! My guess is oxidation on
the contacts and they don't appear to be disassembleable. I may live with
that one rather than replace all the switches.

WT

"Wayne Tiffany" wrote in message
. com...

"Mark D. Zacharias" wrote in message
t...

Page 50 of the PDF (showing page 77 of the paper manual) shows that the
switches involved are part of a resistive ladder arrangement. Obviously,
a problem with the switches here will cause the stated symptom. I would
look no further than this, except perhaps for some contamination on the
board or switches themselves. We sometimes see this type of thing from
people squirting cleaner directly on the screen - it runs down into the
switches.

Mark Z.

Did a little investigating this weekend and I think the problem with these
switches is in the switches. I measured the resistance to ground as I
pressed the switches and they all wander all over the place depending on
how you press them. I'm surprised they work at all! My guess is
oxidation on the contacts and they don't appear to be disassembleable. I
may live with that one rather than replace all the switches.

WT


Sometimes you can improve the action of the switches considerably by
flushing them with DeOxit.

Mark Z.

"Mark D. Zacharias" wrote in message
et...

Sometimes you can improve the action of the switches considerably by
flushing them with DeOxit.

Mark Z.

I'm not sure I could get any into them - they appear to be pretty tight with
no holes in the corners, etc. Thanks.

WT

"Wayne Tiffany" wrote in message
. com...

"Mark D. Zacharias" wrote in message
et...

Sometimes you can improve the action of the switches considerably by
flushing them with DeOxit.

Mark Z.

I'm not sure I could get any into them - they appear to be pretty tight
with no holes in the corners, etc. Thanks.

WT


Naw, just use the pinpoint applicator and force the spray into the switch
where the black little moving button meets the main body of the switch.
After you force some cleaner in there, press the switch maybe 40 or 50
times. It may be easier to remove each switch to work with it, then
re-install after.

Mark Z.

Next frustrating setback. Got the 5v regulator, installed it, not a good
result.

I measured for the 5v and was only getting 4.35. Not a good sign for a new
regulator, and the Sony part to boot. I turned around to look at the
schematic, and heard some soft sound. Didn't see any smoke, but that
regulator was too hot to touch. Quickly pulled the plug and said Hmmm. I
never did try turning the set on because I wanted to make sure I had a good
5v to the micro before I tried anything else. Obviously I didn't get that
far. The fact that I never got to 5v leads me to think that something was
drawing way too much current and the regulator couldn't keep up. One
obvious possibility is the micro on that board.

I might be to the end of my ability to test here not due to lack of good
help, but due to lack of experience and parts. Any other thoughts at this
point?

WT

"Wayne Tiffany" wrote in
. com:

Next frustrating setback. Got the 5v regulator, installed it, not a
good result.

I measured for the 5v and was only getting 4.35. Not a good sign for a
new regulator, and the Sony part to boot. I turned around to look at
the schematic, and heard some soft sound. Didn't see any smoke, but
that regulator was too hot to touch. Quickly pulled the plug and said
Hmmm. I never did try turning the set on because I wanted to make sure
I had a good 5v to the micro before I tried anything else. Obviously I
didn't get that far. The fact that I never got to 5v leads me to think
that something was drawing way too much current and the regulator
couldn't keep up. One obvious possibility is the micro on that board.

I might be to the end of my ability to test here not due to lack of good
help, but due to lack of experience and parts. Any other thoughts at
this point?

Some regulators have overtemp protection built in.
Those can survive an overload like you saw.

The fact that you have a non zero voltage says you don't have a dead short.

You might be able to trace down the overload by measuring resistance.

It would have been better if you had a dead short, however, because then
you could use an ESR meter or low ohm meter to track it down.
You may need to start removing parts, jumpers, and/or cutting traces.

Pick a nice clear run of a trace and cut it with a sharp razor knife. To
patch it later, scrape off the solder resist, tin and solder a bridge
across the cut with a short piece of wire that will handle the current.

Try to isolate various sections in a logical manner.

Don't forget to bridge ALL the cuts!







--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

Pick a nice clear run of a trace and cut it with a sharp razor knife. To
patch it later, scrape off the solder resist, tin and solder a bridge
across the cut with a short piece of wire that will handle the current.

Try to isolate various sections in a logical manner.

Don't forget to bridge ALL the cuts!


That was exactly what I was about to suggest. Done well, it really works.
Start by cutting traces that isolate large sections, then when you find the
short, narrow down.

"bz" wrote in message
98.139...

Some regulators have overtemp protection built in.
Those can survive an overload like you saw.

The fact that you have a non zero voltage says you don't have a dead
short.

You might be able to trace down the overload by measuring resistance.

It would have been better if you had a dead short, however, because then
you could use an ESR meter or low ohm meter to track it down.
You may need to start removing parts, jumpers, and/or cutting traces.

Pick a nice clear run of a trace and cut it with a sharp razor knife. To
patch it later, scrape off the solder resist, tin and solder a bridge
across the cut with a short piece of wire that will handle the current.

Try to isolate various sections in a logical manner.

Don't forget to bridge ALL the cuts!

bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

Good thought - I'll take a look like that when I get a chance. Thanks.

WT

"Wayne Tiffany" wrote in message
. com...

"bz" wrote in message
98.139...

Some regulators have overtemp protection built in.
Those can survive an overload like you saw.

The fact that you have a non zero voltage says you don't have a dead
short.

You might be able to trace down the overload by measuring resistance.

It would have been better if you had a dead short, however, because then
you could use an ESR meter or low ohm meter to track it down.
You may need to start removing parts, jumpers, and/or cutting traces.

Pick a nice clear run of a trace and cut it with a sharp razor knife. To
patch it later, scrape off the solder resist, tin and solder a bridge
across the cut with a short piece of wire that will handle the current.

Try to isolate various sections in a logical manner.

Don't forget to bridge ALL the cuts!

bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is
an
infinite set.

remove ch100-5 to avoid spam trap

Good thought - I'll take a look like that when I get a chance. Thanks.

WT


I will often sub in an external power supply and just see what gets hot. No
need to cut any foil runs at this point.

Mark Z.

"Mark D. Zacharias" wrote in
. net:



I will often sub in an external power supply and just see what gets hot.
No need to cut any foil runs at this point.

You need to be a bit careful to isolate the original supply because back
feeding some supplies can give misleading indications or damage the supply.
For example, I have been told that some 3 terminal regulators are damaged by
back feeding.

Also, you need to make sure you provide ALL + and - voltages in the right
order as some ICs do NOT like it when one or more supply voltages is missing.

Cutting out the 5 volts is unlikely to do MORE damage than has already
occurred but feeding +5 without the -5, +12, -12 [or whatever]
could take out good ICs.

My FAVORITE tool is the 'Curve Tracer' that I build from a 1970's article in
Radio/Television magazine.
It can spot 'sick' gates on an IC, and a lot of other problems 'in circuit'.

It is similar to this one:
http://www.techlib.com/electronics/curvetrace.html

Mine is like the single range model. It is all built into a wall wart except
for the test leads.
I clip my scope to resistor leads that come out through holes in the case.

Anyway, I find it very useful for locating bad transistors and bad gates on
IC because the 'knee' gets rounded or is absent on bad junctions.

Often, you can test 'in circuit', but sometimes you will have to cut some
traces to isolate the junction from caps or resistors that are in parallel
with it.

A little practice with one of these, and a few 'reference junctions' to
compare with the curves you see, and you may love your curve tracer too.

Here is a modern version using your computer's sound card:
http://www.arrl.org/qst/2006/07/steber.pdf





--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

"bz" wrote in message
98.139...
"Mark D. Zacharias" wrote in
. net:



I will often sub in an external power supply and just see what gets hot.
No need to cut any foil runs at this point.

You need to be a bit careful to isolate the original supply because back
feeding some supplies can give misleading indications or damage the
supply.
For example, I have been told that some 3 terminal regulators are damaged
by
back feeding.

Also, you need to make sure you provide ALL + and - voltages in the right
order as some ICs do NOT like it when one or more supply voltages is
missing.

Cutting out the 5 volts is unlikely to do MORE damage than has already
occurred but feeding +5 without the -5, +12, -12 [or whatever]
could take out good ICs.

My FAVORITE tool is the 'Curve Tracer' that I build from a 1970's article
in
Radio/Television magazine.
It can spot 'sick' gates on an IC, and a lot of other problems 'in
circuit'.

It is similar to this one:
http://www.techlib.com/electronics/curvetrace.html

Mine is like the single range model. It is all built into a wall wart
except
for the test leads.
I clip my scope to resistor leads that come out through holes in the case.

Anyway, I find it very useful for locating bad transistors and bad gates
on
IC because the 'knee' gets rounded or is absent on bad junctions.

Often, you can test 'in circuit', but sometimes you will have to cut some
traces to isolate the junction from caps or resistors that are in parallel
with it.

A little practice with one of these, and a few 'reference junctions' to
compare with the curves you see, and you may love your curve tracer too.

Here is a modern version using your computer's sound card:
http://www.arrl.org/qst/2006/07/steber.pdf





--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap

Never had a problem doing this - and in this case it's a single-ended 5 volt
supply. I've even added in a variable supply at the output of a regulator to
supplant the existing regulator while a unit is running. Just reduces the
current requirement on the existing regulator.

Found lots of shorted IC's and the like this way without having to trace a
power supply line all over a complex unit. About the only time this
technique hasn't worked in my experience is when there is a ZERO ohm short,
since some resistance is necessary in order for heat to be generated.


Mark Z.

"M0 D. Zacharias" wrote in
et:

Never had a problem doing this - and in this case it's a single-ended 5
volt supply. I've even added in a variable supply at the output of a
regulator to supplant the existing regulator while a unit is running.
Just reduces the current requirement on the existing regulator.

Found lots of shorted IC's and the like this way without having to trace
a power supply line all over a complex unit. About the only time this
technique hasn't worked in my experience is when there is a ZERO ohm
short, since some resistance is necessary in order for heat to be
generated.

Your method could work on zero ohm shorts, also, IF you happened to have an
IR sensitive camera available.
The trace leading to the short should 'stand out' in an IR view of the
board.

Some CCD cameras are sensitive to IR radiation, so looking at the board
through your camera viewfinder, may show the way to the short.




--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

remove ch100-5 to avoid spam trap