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Identifying a board component out of Clare A433

  1. May 16, 2018 at 8:20 AM #1
    This board is out of an appliance test station (Clare A433). The unit tests the earth circuit, insulation resistance, load current and also has a HV flash probe to check for flashover from live parts to metal casings.

    The insulation resistance function is faulty - it’s meant to apply 1 kV ac between L+N and E (ground) and measure the leakage.

    I’ve narrowed the problem down to this board:UIKEYINPUTRIGHTARROW

    A3096307-F289-4153-BCC4-9522CB995BBC.jpeg

    The component PD1 is open circuit. Here are some details of the numbers, but they are hard to read:

    7801C084-5D28-40DF-9E37-BE157F31DD4F.jpeg FFEB4B11-0050-46CA-A07D-117C2E4758F3.jpeg A427E37D-A608-4DBB-9558-5A59EA08EDB3.jpeg

    Is PD1 a power diode? Do the (obscure) numbers ring a bell? The best I can make out is CP2060A.

    Many thanks.
     
  2. jcsd
  3. May 16, 2018 at 10:30 AM #2

    NascentOxygen

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    Staff: Mentor

    You say PD1 is o/c. Did you establish this using a multimeter set to kilohms? If so, it might be that the voltage the meter applies is too small to cause a perfectly good diode to conduct, and leading to a wrong diagnosis.
     
  4. May 16, 2018 at 11:14 AM #3
    Does PD1 have the dimensions of a DO-27 (or other standard) device form factor? There isn't a polarity band, but perhaps (if it is a power diode) the manufacturer placed the part number text at the extreme end to serve this purpose. CP2060A isn't ringing any bells, but insofar as the circuit board is a 'Clare' it may be an in-house manufacturer's mark ("CP" for CP Clare).
     
  5. May 16, 2018 at 1:40 PM #4
    I tried the diode check function and resistance mode both ways. Auto-ranging meter.

    It seems to be like a DO-14. Looking at the pictures, I wonder if it’s upside-down - you can almost read VD907AD

    Thanks to both for your input, by the way.
     
  6. May 16, 2018 at 2:22 PM #5

    Borek

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    Staff: Mentor

    I wonder if the symbols printed on PCB don't tell us something. Note they are different under resistors and diodes (and shape of the ones under diodes can mark polarity).
     
  7. May 16, 2018 at 2:36 PM #6
    You’re right - the diodes are marked with a form of arrow, as on a schematic. If only there was as much care taken over printing the component numbers!
     
  8. May 16, 2018 at 7:07 PM #7

    wirenut

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    Gold Member

  9. May 16, 2018 at 7:46 PM #8

    Tom.G

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    Science Advisor

    Nice photos!
    How about some of the other side of the board? One of the whole board and one of the region around PD1 and nearby components.
    That may give us some clues about the function of PD1 and needed characteristics.
    It doesn't look like a multilayer board but if it is, some shots with the board backlit to show buried layers would be helpful.

    Cheers,
    Tom
     
  10. May 17, 2018 at 6:56 PM #9

    jim hardy

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    Science Advisor
    Gold Member

    Yes, indeed. With just a little imagination i can see PD1 connected across 7 and 8
    hipottester1.jpg

    suggesting it's perhaps some sort of avalanche overvoltage suppressor .??

    Is my guess about 7&8 right ?

    old jim
     
  11. May 19, 2018 at 3:47 AM #10
    Wirenut - yes, I saw that very one while searching the board number. Nice to know there’s a spare about...

    Tom.G and Jim Hardy - Been rather busy of late, but I’ll update soon. A brief test recently showed the unit works (I think) as normal now. It could have been a simple loose connection, then. I’d still like to get to the bottom of that component, though, so more photos and details to follow...

    An interesting device and an ebay bargain - just £22. The Clare A433 is a ‘comprehensive test station’ for periodic, post-repair and type testing of electrical appliances, both 110V and 240V. Made c. 1988.

    Since there are frustratingly few details online, I’ve looked over it with my meter and cobbled together a sketch of its features:

    (L = live, active, hot, phase; N = neutral; E, Earth = ground.)
    1. 500mV ac continuity test - for verifying earth pin connection to casing?

    2. Earth bond test - 8V ac and up to 36A through the earth path. Measures down to 0.05 ohm. Heavy current ensures any feeble connections or wispy wires are uncovered.

    3. L+N to probe 0-5000V ac - checks for flashover between live conductors and any metal parts, which are probed with the ‘flash prod’. Voltage variable with what looks like a variac-type rotary brush contact. Trips (with buzzer alarm and neon lamp) at a selectable 5, 10 or 15mA level. I will use this with care, since 5000V ac at 15 mA sounds rather lethal.

    4. L+N to E 0-5000V ac - insulation resistance. Measures leakage to earth at a suggested setting of 1 kV. Scale in megohms and leakage in mA.

    5. Load test - runs the appliance and measures current, scale 15 or 1.5 A.
     
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