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Sharp Microwave powers down.....

Discussion in 'Electronic Repair' started by electroninja, Jan 11, 2005.

  1. electroninja

    electroninja Guest

    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
     
  2. NSM

    NSM Guest

    | 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
     
  3. 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.
     
  4. NSM

    NSM Guest

    | 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
     
  5. electroninja

    electroninja Guest

    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.
     
  6. electroninja

    electroninja Guest

    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.
     
  7. 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.
     
  8. 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.
     
  9. electroninja

    electroninja Guest

    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!
     
  10. electroninja

    electroninja Guest

    Does it work--do you want to sell it?
     
  11. NSM

    NSM Guest

    | 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
     
  12. electroninja

    electroninja Guest

    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?
     
  13. NSM

    NSM Guest

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

    Stein
     
  15. NSM

    NSM Guest

    |
    | 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
     
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