Hey all;

I'm working on repairing a Heath weather computer. Initially, none of the
funcitons really worked (temp, pressure, clock, etc.) I got it to the point
last night where everything was working except the clock, which kept time,
but I couldn't actually set it. So, I (stupidly?) poked around a little more
to try to get the clock going. I noticed a 4066 with some black stuff on the
pins, and some weird voltages around it, so I pulled it out, fired the unit
up, and checked the voltages again. They were still weird, but when I put it
back in and turned it on again, the pressure and temperature stayed at 0. I
was messing around with it again tonite, and the pressure and temperature
readings were more normal, but I noticed a couple of opamps (in different
locations) that were hot to the touch. There were no shorts in either of
them, and the voltages around them pretty much matched the schematic. I now
get bad readings in the temperature (-40) and pressure (0). I'm guessing the
opamps are at least part of the problem. Any idea why they are getting so
hot? Any other suggestions?

Thanks

"tempus fugit" wrote in message
...
Hey all;

I'm working on repairing a Heath weather computer.

Personally, I always suspect 4066's, and as for op-amps I always suspect
324's

If things are getting hot, then are you sure that the supplies are present
and correct and that nothing is shorted. If the opamps are getting hot, then
it's a possibility they're drawing a lot of current, and that will affect
the operation of the entire unit.

You might also get some useful info from this page
http://www.heathkit-museum.com/support.shtml

Thanks Nigel.

Guess what kind of opamps they are - yup, LM324. When you say "suspect" do
you mean you suspect they have failed?

I've been toying with the idea of replacing the opamps with a 074, but I
don't want to end up just burning another opamp. I'm wondering whether other
components have caused the opamp failure, although everything around them
seems to be testing OK.


"Nigel" wrote in message
...

"tempus fugit" wrote in message
...
Hey all;

I'm working on repairing a Heath weather computer.

Personally, I always suspect 4066's, and as for op-amps I always suspect
324's

If things are getting hot, then are you sure that the supplies are present
and correct and that nothing is shorted. If the opamps are getting hot,
then
it's a possibility they're drawing a lot of current, and that will affect
the operation of the entire unit.

You might also get some useful info from this page
http://www.heathkit-museum.com/support.shtml

"tempus fugit" wrote in message
...
Hey all;

I'm working on repairing a Heath weather computer. Initially, none of the
funcitons really worked (temp, pressure, clock, etc.) I got it to the
point
last night where everything was working except the clock, which kept time,
but I couldn't actually set it. So, I (stupidly?) poked around a little
more
to try to get the clock going. I noticed a 4066 with some black stuff on
the
pins, and some weird voltages around it, so I pulled it out, fired the
unit
up, and checked the voltages again. They were still weird, but when I put
it
back in and turned it on again, the pressure and temperature stayed at 0.
I
was messing around with it again tonite, and the pressure and temperature
readings were more normal, but I noticed a couple of opamps (in different
locations) that were hot to the touch. There were no shorts in either of
them, and the voltages around them pretty much matched the schematic. I
now
get bad readings in the temperature (-40) and pressure (0). I'm guessing
the
opamps are at least part of the problem. Any idea why they are getting so
hot? Any other suggestions?

Thanks


From your description, I'd guess that your problem is intermittent, and may
be easily repairable.
When you say that there is "black stuff" on the pins of the 4066, is it just
tarnish or something else? If it's tarnish, then that could be the majority
of your problems. I assume that the ICs are socketed. If so, you can use
any of a few methods to clean the tarnish off the pins. The quickest is
Tarn-X, but you have to rinse them very well afterwards with clean water.
Don't leave *any* Tarn-X residue on the pins, since it is corrosive.
Another cleaning method is with a rubber pencil eraser. Be careful with
this, since it is easy to bend/break the pins.
What condition are the IC sockets in? They may need to be cleaned or
replaced if they are in bad condition.
How hot are the opamps? Are they just warm or really hot? If they're just
warm, it may be normal, depending on the circuit. Opamps usually are
low-level components... that is, they don't handle any appreciable power,
and usually run pretty cool.
Is the schematic of the unit available on the web anywhere, or can you post
it to the binaries NG? Might help with some suggestions to help you.
--
Tweetldee
Tweetldee at att dot net (Just subsitute the appropriate characters in the
address)

Never take a laxative and a sleeping pill at the same time!!

Thanks tweet.

The black stuff is actually on quite a few of the components - diode leads,
resistors, ICs, etc. I never really looked too close at it, but it almost
looks like black paint.
The opamps are HOT. They start out cold, and after about 2 minutes are too
hot to touch. I have the original schematic, as well as the manual, but
have noticed some errors on the schem (or the circuit board, I don't know
which). One thing that I have noticed on a lot of components (mostly
xsistors) is odd voltage readings. There might be 5v on one side of a bias
resistor, and 0.3v on the other (xsistor) side, but the xsistor checks out
OK with a diode test (i.e., not leaky or shorted).

Thanks



From your description, I'd guess that your problem is intermittent, and
may
be easily repairable.
When you say that there is "black stuff" on the pins of the 4066, is it
just
tarnish or something else? If it's tarnish, then that could be the
majority
of your problems. I assume that the ICs are socketed. If so, you can use
any of a few methods to clean the tarnish off the pins. The quickest is
Tarn-X, but you have to rinse them very well afterwards with clean water.
Don't leave *any* Tarn-X residue on the pins, since it is corrosive.
Another cleaning method is with a rubber pencil eraser. Be careful with
this, since it is easy to bend/break the pins.
What condition are the IC sockets in? They may need to be cleaned or
replaced if they are in bad condition.
How hot are the opamps? Are they just warm or really hot? If they're
just
warm, it may be normal, depending on the circuit. Opamps usually are
low-level components... that is, they don't handle any appreciable power,
and usually run pretty cool.
Is the schematic of the unit available on the web anywhere, or can you
post
it to the binaries NG? Might help with some suggestions to help you.
--
Tweetldee
Tweetldee at att dot net (Just subsitute the appropriate characters in
the
address)

Never take a laxative and a sleeping pill at the same time!!

"tempus fugit" wrote in message
...
Thanks tweet.

The black stuff is actually on quite a few of the components - diode
leads,
resistors, ICs, etc. I never really looked too close at it, but it almost
looks like black paint.
The opamps are HOT. They start out cold, and after about 2 minutes are too
hot to touch. I have the original schematic, as well as the manual, but
have noticed some errors on the schem (or the circuit board, I don't know
which). One thing that I have noticed on a lot of components (mostly
xsistors) is odd voltage readings. There might be 5v on one side of a bias
resistor, and 0.3v on the other (xsistor) side, but the xsistor checks out
OK with a diode test (i.e., not leaky or shorted).

Thanks



From your description, I'd guess that your problem is intermittent, and
may
be easily repairable.
When you say that there is "black stuff" on the pins of the 4066, is it
just
tarnish or something else? If it's tarnish, then that could be the
majority
of your problems. I assume that the ICs are socketed. If so, you can
use
any of a few methods to clean the tarnish off the pins. The quickest is
Tarn-X, but you have to rinse them very well afterwards with clean
water.
Don't leave *any* Tarn-X residue on the pins, since it is corrosive.
Another cleaning method is with a rubber pencil eraser. Be careful with
this, since it is easy to bend/break the pins.
What condition are the IC sockets in? They may need to be cleaned or
replaced if they are in bad condition.
How hot are the opamps? Are they just warm or really hot? If they're
just
warm, it may be normal, depending on the circuit. Opamps usually are
low-level components... that is, they don't handle any appreciable
power,
and usually run pretty cool.
Is the schematic of the unit available on the web anywhere, or can you
post
it to the binaries NG? Might help with some suggestions to help you.
--
Tweetldee


Undoubtedly, the "black stuff" that you see on the leads is tarnish. It's
not dangerous to the components, but if it's interfering with mating of
component contacts, it will certainly prevent the circuit from operating
correctly. This could be the problem with the opamps.
There's something seriously out of whack if the opamps are too hot to
touch.. Don't allow it to run for more than just a few seconds until you
get it fixed.. the opamps will be destroyed, if they are not defective
already.
I can't tell a thing from your voltage measurements without seeing the
schematic along with the voltages. It certainly would be a big help if you
could scan the schematic and post it somewhere. Without it, it's pretty
much a waste of time here.
--
Tweetldee
Tweetldee at att dot net (Just subsitute the appropriate characters in the
address)

Never take a laxative and a sleeping pill at the same time!!

Thanks again.
Unforunately, I don't think I can scan the schem (it's huge for one thing).
As for the voltages, they don't match up with what's indicated on the schem
in a lot of places (even when I had most of it working), so I don't know
which to trust. I'll try removing the tarnish and checking for continuity
though.
Thanks


"Tweetldee" wrote in message
...
"tempus fugit" wrote in message
...
Thanks tweet.

The black stuff is actually on quite a few of the components - diode
leads,
resistors, ICs, etc. I never really looked too close at it, but it
almost
looks like black paint.
The opamps are HOT. They start out cold, and after about 2 minutes are
too
hot to touch. I have the original schematic, as well as the manual, but
have noticed some errors on the schem (or the circuit board, I don't
know
which). One thing that I have noticed on a lot of components (mostly
xsistors) is odd voltage readings. There might be 5v on one side of a
bias
resistor, and 0.3v on the other (xsistor) side, but the xsistor checks
out
OK with a diode test (i.e., not leaky or shorted).

Thanks



From your description, I'd guess that your problem is intermittent,
and
may
be easily repairable.
When you say that there is "black stuff" on the pins of the 4066, is
it
just
tarnish or something else? If it's tarnish, then that could be the
majority
of your problems. I assume that the ICs are socketed. If so, you can
use
any of a few methods to clean the tarnish off the pins. The quickest
is
Tarn-X, but you have to rinse them very well afterwards with clean
water.
Don't leave *any* Tarn-X residue on the pins, since it is corrosive.
Another cleaning method is with a rubber pencil eraser. Be careful
with
this, since it is easy to bend/break the pins.
What condition are the IC sockets in? They may need to be cleaned or
replaced if they are in bad condition.
How hot are the opamps? Are they just warm or really hot? If they're
just
warm, it may be normal, depending on the circuit. Opamps usually are
low-level components... that is, they don't handle any appreciable
power,
and usually run pretty cool.
Is the schematic of the unit available on the web anywhere, or can you
post
it to the binaries NG? Might help with some suggestions to help you.
--
Tweetldee


Undoubtedly, the "black stuff" that you see on the leads is tarnish. It's
not dangerous to the components, but if it's interfering with mating of
component contacts, it will certainly prevent the circuit from operating
correctly. This could be the problem with the opamps.
There's something seriously out of whack if the opamps are too hot to
touch.. Don't allow it to run for more than just a few seconds until you
get it fixed.. the opamps will be destroyed, if they are not defective
already.
I can't tell a thing from your voltage measurements without seeing the
schematic along with the voltages. It certainly would be a big help if
you
could scan the schematic and post it somewhere. Without it, it's pretty
much a waste of time here.
--
Tweetldee
Tweetldee at att dot net (Just subsitute the appropriate characters in
the
address)

Never take a laxative and a sleeping pill at the same time!!

You don't need to worry about the tarnish on the soldered component leads..
just the socketed components, such as ICs and transistors. If there are any
connectors that appear to be tarnished, then you should clean those as well.
BTW, have you checked the power supply output(s) with your multimeter? If
the supply voltages aren't correct, then you can't expect the rest of the
circuit to operate properly. How abot ripple on the PS lines? If there's a
lot of ripple, then there will be all sorts of chaos in the circuit.
--
Tweetldee
Tweetldee at att dot net (Just subsitute the appropriate characters in the
address)

Never take a laxative and a sleeping pill at the same time!!
"tempus fugit" wrote in message
...
Thanks again.
Unforunately, I don't think I can scan the schem (it's huge for one
thing).
As for the voltages, they don't match up with what's indicated on the
schem
in a lot of places (even when I had most of it working), so I don't know
which to trust. I'll try removing the tarnish and checking for continuity
though.
Thanks


"Tweetldee" wrote in message
...
"tempus fugit" wrote in message
...
Thanks tweet.

The black stuff is actually on quite a few of the components - diode
leads,
resistors, ICs, etc. I never really looked too close at it, but it
almost
looks like black paint.
The opamps are HOT. They start out cold, and after about 2 minutes are
too
hot to touch. I have the original schematic, as well as the manual,
but
have noticed some errors on the schem (or the circuit board, I don't
know
which). One thing that I have noticed on a lot of components (mostly
xsistors) is odd voltage readings. There might be 5v on one side of a
bias
resistor, and 0.3v on the other (xsistor) side, but the xsistor checks
out
OK with a diode test (i.e., not leaky or shorted).

Thanks



From your description, I'd guess that your problem is intermittent,
and
may
be easily repairable.
When you say that there is "black stuff" on the pins of the 4066, is
it
just
tarnish or something else? If it's tarnish, then that could be the
majority
of your problems. I assume that the ICs are socketed. If so, you
can
use
any of a few methods to clean the tarnish off the pins. The
quickest
is
Tarn-X, but you have to rinse them very well afterwards with clean
water.
Don't leave *any* Tarn-X residue on the pins, since it is corrosive.
Another cleaning method is with a rubber pencil eraser. Be careful
with
this, since it is easy to bend/break the pins.
What condition are the IC sockets in? They may need to be cleaned
or
replaced if they are in bad condition.
How hot are the opamps? Are they just warm or really hot? If
they're
just
warm, it may be normal, depending on the circuit. Opamps usually
are
low-level components... that is, they don't handle any appreciable
power,
and usually run pretty cool.
Is the schematic of the unit available on the web anywhere, or can
you
post
it to the binaries NG? Might help with some suggestions to help
you.
--
Tweetldee


Undoubtedly, the "black stuff" that you see on the leads is tarnish.
It's
not dangerous to the components, but if it's interfering with mating of
component contacts, it will certainly prevent the circuit from operating
correctly. This could be the problem with the opamps.
There's something seriously out of whack if the opamps are too hot to
touch.. Don't allow it to run for more than just a few seconds until
you
get it fixed.. the opamps will be destroyed, if they are not defective
already.
I can't tell a thing from your voltage measurements without seeing the
schematic along with the voltages. It certainly would be a big help if
you
could scan the schematic and post it somewhere. Without it, it's pretty
much a waste of time here.
--
Tweetldee
Tweetldee at att dot net (Just subsitute the appropriate characters in
the
address)

Never take a laxative and a sleeping pill at the same time!!

Hey Tweetldee;

I don't know if I mentioned in my OP, but the 1st thing that was wrong was a
defective -15v regulator. I'm wondering if all the ICs that needed +/-15v
got damaged (these would be the 4016, 324, and a couple 1458s). The voltages
around these seem OK though, and there are no direct shorts. Maybe I'll try
replacing them and see what happens. They're cheap, so it will only end up
costing a couple bucks.


"Tweetldee" wrote in message
...

"tempus fugit" wrote in message
...
Hey all;

I'm working on repairing a Heath weather computer. Initially, none of
the
funcitons really worked (temp, pressure, clock, etc.) I got it to the
point
last night where everything was working except the clock, which kept
time,
but I couldn't actually set it. So, I (stupidly?) poked around a little
more
to try to get the clock going. I noticed a 4066 with some black stuff on
the
pins, and some weird voltages around it, so I pulled it out, fired the
unit
up, and checked the voltages again. They were still weird, but when I
put
it
back in and turned it on again, the pressure and temperature stayed at
0.
I
was messing around with it again tonite, and the pressure and
temperature
readings were more normal, but I noticed a couple of opamps (in
different
locations) that were hot to the touch. There were no shorts in either of
them, and the voltages around them pretty much matched the schematic. I
now
get bad readings in the temperature (-40) and pressure (0). I'm guessing
the
opamps are at least part of the problem. Any idea why they are getting
so
hot? Any other suggestions?

Thanks


From your description, I'd guess that your problem is intermittent, and
may
be easily repairable.
When you say that there is "black stuff" on the pins of the 4066, is it
just
tarnish or something else? If it's tarnish, then that could be the
majority
of your problems. I assume that the ICs are socketed. If so, you can use
any of a few methods to clean the tarnish off the pins. The quickest is
Tarn-X, but you have to rinse them very well afterwards with clean water.
Don't leave *any* Tarn-X residue on the pins, since it is corrosive.
Another cleaning method is with a rubber pencil eraser. Be careful with
this, since it is easy to bend/break the pins.
What condition are the IC sockets in? They may need to be cleaned or
replaced if they are in bad condition.
How hot are the opamps? Are they just warm or really hot? If they're
just
warm, it may be normal, depending on the circuit. Opamps usually are
low-level components... that is, they don't handle any appreciable power,
and usually run pretty cool.
Is the schematic of the unit available on the web anywhere, or can you
post
it to the binaries NG? Might help with some suggestions to help you.
--
Tweetldee
Tweetldee at att dot net (Just subsitute the appropriate characters in
the
address)

Never take a laxative and a sleeping pill at the same time!!

tempus fugit wrote:

Hey Tweetldee;

I don't know if I mentioned in my OP, but the 1st thing that was wrong was
a defective -15v regulator. I'm wondering if all the ICs that needed
+/-15v got damaged (these would be the 4016, 324, and a couple 1458s). The
voltages around these seem OK though, and there are no direct shorts.
Maybe I'll try replacing them and see what happens. They're cheap, so it
will only end up costing a couple bucks.

Those 40xx CMOS parts don't do real well with over-voltage on the supply
lines...

See if any of them are at all warm to the touch -- if so, then _those_ are
the ones that need to be replaced.

On Fri, 24 Oct 2003 23:18:04 -0400, tempus fugit wrote:
Hey all;
I'm working on repairing a Heath weather computer. Initially, none of the
funcitons really worked (temp, pressure, clock, etc.
Thanks

Please get on this Heathkit list.
You will find a great deal of help there.

"Heathkit List"
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