Merc-o-tronic repair help.

[foodclub]

Hi all,

Have a Merc-o-Tronic 98. All of the coil test procedures work fine. However, none of the condenser tests work. Seems, when you press the red button for any of the tests, including indexing the meter to the right, NOTHING happens. I have no electronic skills. Is there anyone here that can fix them, or is there anyplace to go to get them fixed?

Thanks!

[crosbyman]

solid failures are sometimes the easiest to fix…

try to look for any blown fuses…. broken wires …… bad/defective push switched

Joining AOMCI has priviledges 🙂

[debe]

If this is the same circuit board, then check for 5V dc on pin 8 of the NE555 ic as shown for a start.

[wbeaton]

Mine has the same problem. I didn’t know at the time that you can’t have the 6VDC and 120VAC plugged in at the same time.

Wayne
Upper Canada Chapter

uccaomci.com

[foodclub]

quote debe:

If this is the same circuit board, then check for 5V dc on pin 8 of the NE555 ic as shown for a start.

Nope, No Circuit Board. 🙁

[foodclub]

quote wbeaton:

Mine has the same problem. I didn’t know at the time that you can’t have the 6VDC and 120VAC plugged in at the same time.

Hmmm… Interesting and raises a number of questions. BTW, I tried both ways (DC and no DC).

Does plugging in the unit while there is a battery connected damage the unit?
Seems odd that the battery goes in the unit and you screw the lid down, but to use the condenser test, you have to take battery out to plug it in?
Didn’t see anything in the manual that indicated that you had to take battery out. Where did you learn this?

Thanks for the help!

[Mumbles]

My 98 uses a 7.5 volt power supply mounted inside the case and tapped into the main supply line. The switch on the left chooses which power source to use. Also, check your indicator light bulb as I believe it might be wired in series in the 7.5 volt system.

[foodclub]

quote Mumbles:

My 98 uses a 7.5 volt power supply mounted inside the case and tapped into the main supply line. The switch on the left chooses which power source to use. Also, check your indicator light bulb as I believe it might be wired in series in the 7.5 volt system.

Thanks! Have the original spec 7.5v alkaline. The indicator bulb and the vibrator work fine (DC). On setting 1 and 2, everything checks out. I believe that switch setting 1 and 2 use DC and 4,5,6 us AC, so that would be accurate (switch on the left chooses which power to use).

Search continues!

[jeff-register]

The NE555 has been around forever

[wbeaton]

quote foodclub:

Hmmm… Interesting and raises a number of questions. BTW, I tried both ways (DC and no DC).

Does plugging in the unit while there is a battery connected damage the unit?
Seems odd that the battery goes in the unit and you screw the lid down, but to use the condenser test, you have to take battery out to plug it in?
Didn’t see anything in the manual that indicated that you had to take battery out. Where did you learn this?

Thanks for the help!

I think the issue is related to trying to perform the tests with two power supplies connected. Its not in the manual. Someone more knowledgeable in electronics and Merc-o-tornics told me about it on this board years ago. Perhaps I’ll see if I can fix mine this winter.

Wayne
Upper Canada Chapter

uccaomci.com

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