Sharp Microwave powers down.....

[electroninja]

Sam and NSM:
Changed zener w/5.1v-- monitor lights dimmed otherwise no
change--replaced new zener with old and lights returned to normal--dead
end there I quess.

Any recommendations on board repair--pull and check every
component?--caps before resistors? Replace LC first? Have only VOM for
test equip with diode/transistor settings?

Thanks

 

[NSM]

| Sam and NSM:
| Changed zener w/5.1v-- monitor lights dimmed otherwise no
| change--replaced new zener with old and lights returned to normal--dead
| end there I quess.
|
| Any recommendations on board repair--pull and check every
| component?--caps before resistors? Replace LC first? Have only VOM for
| test equip with diode/transistor settings?

Sadly, even I will give up at some point. If I can't spot a damaged part I
know how impossible some repairs are. If you could find a working unit you
could compare voltages, signals etc. But most microprocessor controlled
devices can only be fixed now with a good service manual and the required
tools.

N

 

[Sam Goldwasser]

Sam and NSM:
Changed zener w/5.1v-- monitor lights dimmed otherwise no
change--replaced new zener with old and lights returned to normal--dead
end there I quess.

Any recommendations on board repair--pull and check every
component?--caps before resistors? Replace LC first? Have only VOM for
test equip with diode/transistor settings?

Either the microprocessor or its firmware is broken, or something is
tellting it to power down, like the sensor. Can you trace the sensor input
to where it goes. Maybe check components associated with that circuit.

And, of course, the DC power supplies. However, without an oscilloscope,
you won't be able to catch a momentary fluctuation. But at least you
can test to your heart's content without worrying about the high voltage
and microwave dangers as long as the HV transformer primary is disconnected.

Unfortunately, this is the type of problem that will produce premature
baldness in even experience techs and engineers.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

 

[NSM]

| Unfortunately, this is the type of problem that will produce premature
| baldness in even experience techs and engineers.

I recall my old boss telling me that when he worked for Philips repairing
tube radios one tech got so PO'd that he picked up the radio he was working
on and smashed it on the floor. Then he got a new case and rebuilt the
radio.

N

 

[electroninja]

Would have quit days ago myself except for the fact it's a built-in for
our motor home--maybe I can train a pet to keep pushing the start
button every 40 or 50 seconds.

 

[electroninja]

I miss my old Heathkit Osc--in those days if you had access to a 5 Mhz
or better a 20 Mhz dual trace you were really somebody!

I'm going to hang in there for a few more days--got some part catalogs
coming--been looking for an excuse to buy a new O, but I see on web
search that 100 buck won't even cover the leads anymore--where have I
been for the last 30 years

Thanks guys.

 

[Sam Goldwasser]

I miss my old Heathkit Osc--in those days if you had access to a 5 Mhz
or better a 20 Mhz dual trace you were really somebody!

I'm going to hang in there for a few more days--got some part catalogs
coming--been looking for an excuse to buy a new O, but I see on web
search that 100 buck won't even cover the leads anymore--where have I
been for the last 30 years

eBay. With some care in selection, patience, and just a bit of luck,
you can get a 50 MHz or better Tek scope for under $100.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

 

[Sam Goldwasser]

I miss my old Heathkit Osc--in those days if you had access to a 5 Mhz
or better a 20 Mhz dual trace you were really somebody!

I'm going to hang in there for a few more days--got some part catalogs
coming--been looking for an excuse to buy a new O, but I see on web
search that 100 buck won't even cover the leads anymore--where have I
been for the last 30 years

I still have my 5 MHz Heathkit scope, somewhere.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

 

[electroninja]

Any particular model Tek you might recommend?--I won't be plotting
spectral emission char's for GaA emitters or anything like that. Ha Ha!

 

[electroninja]

Does it work--do you want to sell it?

 

[NSM]

| I miss my old Heathkit Osc--in those days if you had access to a 5 Mhz
| or better a 20 Mhz dual trace you were really somebody!
|
| I'm going to hang in there for a few more days--got some part catalogs
| coming--been looking for an excuse to buy a new O, but I see on web
| search that 100 buck won't even cover the leads anymore--where have I
| been for the last 30 years

I've gotten some fantastic 'scope bargains on eBay recently. I wound up with
a dual channel 100 MHz scope with delay time base for $50.

N

 

[electroninja]

I'll keep my eyes open--I just don't want to be posting "Tek scope
powers down after...." if you know what I mean?

 

[NSM]

| I'll keep my eyes open--I just don't want to be posting "Tek scope
| powers down after...." if you know what I mean?

Oh sure, but a several hundred dollar scope for $50 is hard to beat.

N

 

[Stein-Olav Lund]

| Unfortunately, this is the type of problem that will produce premature
| baldness in even experience techs and engineers.

I recall my old boss telling me that when he worked for Philips repairing
tube radios one tech got so PO'd that he picked up the radio he was working
on and smashed it on the floor. Then he got a new case and rebuilt the
radio.

N

Having seen (and repaired) several old radios of that brand I quite
understand him, frankly...

Stein

 

[NSM]

|
| NSM wrote:
| > I recall my old boss telling me that when he worked for Philips
repairing
| > tube radios one tech got so PO'd that he picked up the radio he was
working
| > on and smashed it on the floor. Then he got a new case and rebuilt the
| > radio.

| Having seen (and repaired) several old radios of that brand I quite
| understand him, frankly...

Yes. Some of the dial stringing was clearly designed by the psychotic
inmates of the worst of asylums.

N