| Electronics > Repair |
| Metex M-3610 repair help - dmm won't zero properly in ohms and DC volts |
| (1/1) |
| retiredcaps:
I got this Metex M-3610 for free. It looks like it was made in 1987. Unfortunately, it doesn't zero when I touch the probes together on DC voltage. It reads about 0.250Vs when the probes are not touching. When I measure a 9V battery, it reads 0.63V even though it is a new battery. On resistance mode, the multimeter correctly shows "1" or out of range when the probes are not touching, but when I touch the probes together, I get 25 ohms. I have tried known good probes and fresh akaline batteries so I'm sure the problem is with the M-3610 itself. It uses the IC7106 chip and in the datasheet at http://pdf1.alldatasheet.com/datasheet-pdf/view/177757/INTERSIL/ICL7106CPLZ.html it talks about AN032 "Understanding the Auto-Zero and Common Mode Performance of the ICL7136/7/9 Family", but for the life of me, I cannot find the datasheet/app note anywhere. I'm assuming my problem is with the auto-zero function, but without the app note, I'm not sure what exactly to test. Suggestions would be appreciated. I know this multimeter isn't worth much, but I want to learn more about electronics and this is a great opportunity. PS. Now I know why Dave Jones hates those 9V wires. I managed to damage the red wire when snapping back the case on. I didn't see it trapped between the case and screw hole when I put the front cover back on. :'( |
| amyk:
That looks like the ancestor of the infamous DT-830 series. Apart from checking to see if any components have drifted out of spec, the only other culprit is the '7106 itself. |
| retiredcaps:
--- Quote from: amyk on March 12, 2012, 11:02:20 am ---That looks like the ancestor of the infamous DT-830 series. --- End quote --- Yes, I had the same thought when I saw the 7106 chip. At least I have your Elenco kit instruction manual allow with the 7106 datasheet to give me some idea how it works. --- Quote ---Apart from checking to see if any components have drifted out of spec, the only other culprit is the '7106 itself. --- End quote --- Well, there aren't too many components so I guess I will start checking in circuit first and anything that looks suspicious will warrant desoldering and retesting out of circuit. Thanks again for your input. It is appreciated. |
| retiredcaps:
FYI. More rebadged dmm!! Saw this thread and watched the video. https://www.eevblog.com/forum/general-chat/fake-transistors-!-never/ I noticed that the SkyTronics 600.527 is identical to the Metex M-3610 (made in 1986). |
| wkb:
;D That is the same multimeter as one in my collection. Mine still works just fine btw. |
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