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| Metrix MX407 megohmmeter - Quick teardown and repair. |
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| on4top:
Z3 seems to be a 12V zener diode . I removed it and made al smal test-setup . Z5 and Z2 are now removed and the meter seems to work .. https://photos.app.goo.gl/cREkBAY4zNpfV5qQ6 Sad we don't have schematics ... Z5 and Z2 must have a reason . With Z3 removed measuring ohm is broken . The question now is what is the value of Z5 and Z2 .. also 12V ..or someting else . ( they all look the same those SMD Zeners ) |
| shakalnokturn:
I just repaired another of these with a suspicious (as in fake-looking) 2SD882 transformer primary switcher that had fused open without signs of heat, cracks or craters. In case the values of Z2 and Z5 are needed they both test in the 28-30V range @ 2mA. I made a quick test setup too... Edit: Added photos. There's nothing that smells NEC about that transistor... |
| shakalnokturn:
Having found a few more MX407's to repair, removing the rear PCB to clean switch contacts I noticed that the front PCB was marked "CA6527". Funnily there is no Chauvin-Arnoux branded 6527 sold in Europe the 6527 is an Americas only AEMC model. |
| Breizh13:
Hello to everyone on this thread, from France. I also bought this MX407 on a flea market, for not much. I had been looking at it with the intention of getting it to work, then it sat in a drawer for a long time. Turns out it's the same components that are burned, Z5, D12 and Q15. Did anyone finally find the values for Z5 and D12. For the transistor, I saw that it was a 2SD882. I'll be glad to read you again with the hope of bringing this device back to life. -- Philippe |
| shakalnokturn:
Don't know about D12 but not zener, worth checking reverse voltage in circuit or going for a 1kV blocking model. Z5 is 28 or 30V zener I doubt it matters much. |
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