Connect with us

Hitachi shut down

Discussion in 'Electronic Repair' started by [email protected], Feb 14, 2005.

Scroll to continue with content
  1. Guest

    Same problem, just more info to post. Hitachi 50EX10B, press power
    button, led comes on, set shuts off. Stand by power OK. Kept blowing B+
    fuses after replacing the HOT. I disconnected the anode of the green
    CRT, and it doesn't blow fuses anymore. Other tubes OK. But, the dang
    thing still will not power up. Same symptom above except not blowing
    fuse with green tube disconnected. Flyback checked good. Resoldered the
    drive transformer posts as was suggested, but no luck. I believe I have
    a 2 part problem. Probable bad green tube blowing fuse, and something
    else sending set into shutdown at power up. Have to unplug, and plug
    back in to get power led to light. Otherwise the power button will
    still cycle the relay, but no light from power led. Hope someone has
    experience with a similiar problem. Thanks group.
     
  2. Jerry G.

    Jerry G. Guest

    How did you check the flyback???

    --

    Jerry G.
    ======


    Same problem, just more info to post. Hitachi 50EX10B, press power
    button, led comes on, set shuts off. Stand by power OK. Kept blowing B+
    fuses after replacing the HOT. I disconnected the anode of the green
    CRT, and it doesn't blow fuses anymore. Other tubes OK. But, the dang
    thing still will not power up. Same symptom above except not blowing
    fuse with green tube disconnected. Flyback checked good. Resoldered the
    drive transformer posts as was suggested, but no luck. I believe I have
    a 2 part problem. Probable bad green tube blowing fuse, and something
    else sending set into shutdown at power up. Have to unplug, and plug
    back in to get power led to light. Otherwise the power button will
    still cycle the relay, but no light from power led. Hope someone has
    experience with a similiar problem. Thanks group.
     
  3. Jeff Rigby

    Jeff Rigby Guest

    If the set has too much HV the green crt is the first to break as an arc
    snaps thru the glass. The set should have gone into shutdown fast enough to
    not have broken the green crt.

    Someone probably defeated shutdown for diagnostic purposes. The only safe
    way to service the set is to disconnect the picture tubes first then confirm
    with a HV meter that the HV is not going too high. The Switching regulator
    is probably outputting too much voltage. Other circuits can be damaged if
    you defeat the shutdown.
     
  4. Guest

    I replaced the switching regulator already, and 2 other transistors
    that were suspect in the power supply. All with Hitachi replacements. I
    wasn't getting steady voltage readings, they were cycling slightly
    above to almost zero compared to the schematic. I'm not sure though how
    to check Q702 which I think is an SCR (part of protective circuit). I
    have read that someone with similiar symptom replaced a leaky one that
    repaired the set. There are also 2 IC's - 902, 903, protective and
    regulator respectively. Both are exact same circuit wise, but don't
    check the same with diode/ohm check. Thanks for the info, any other
    ideas?
     
  5. Techforce

    Techforce Guest

    | Thanks for the info, any other ideas?


    The Flyback is part No. 2436493 subbed to a 2436493/A , NLA from Hitachi
    but its a high fail common problem in this chassis that does cause shutdown.
    Originals can be purchased online here:
    http://www.technotronic-dimensions.com/Products2.html
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-