Help with a exetech 381295 scopemeter

[nightrider0614]

I bought this scopemeter and the buttons on the front panel don't work. I should say none but the power button. I can plug in the serial connector and control from a computer but it's not very portable. And the backlight doesn't work.

I know it's nothing special but it's all I have right now. I have tested the buttons from ground and seen to have -2.75v and +2.75v on the two button connections.

If anyone has some tips on where to start troubleshooting that would be great!

Thanks,
Jeff

 

[PedroDaGr8]

Good pics of the board would help. It sounds like this was abused pretty badly. I see this particular model listed under a few brand names like Protek, Sontek, etc. Still can't figure out who the ODM is. Extech stuff is usually rebadged CEM (with the occasional Brymen rebadge). This scope meter doesn't seem like either of those companies.

 

[nightrider0614]

Pics

I dont think it was abused. The person that I got it off of said he let it sit for a really long time and the buttons started to drop out. I was able to hold a few buttons down and power it on and it came up once (the buttons worked, but slowly quit one by one) It has a nec d78 processor in it. M

I just put a fresh battery in it so there shouldn't be a voltage issue.

I will take a voltmeter to it and try to trace the runs down.

Here are a few inside and outside pics.

Thanks!

 

[nightrider0614]

Pics

 

[nightrider0614]

And it does work. I just have to have the serial cable connected. But you can't access the backlight from the software. 🙁

 

[Max Headroom]

Most likely that the rubber membrane keypad carbon contacts have gone sour.
Standard TV/Audio etc remote controls use this kind of keypad.

Procedure that works is to wash the carbon contacts (the whole rubber keypad) with warm water, dish washing detergent and lint free cloth, and rinse until perfectly clean of detergent.
When dry, use a cotton bud and isopropyl alcohol to cleanse the carbon contacts, and also the pcb gold contacts.

Assemble and it should work fine.

Dan.

 

[nightrider0614]

Thanks dan and pedrodagr8
That was awesome. I washed and dried the keypad previously because that was my first thought, but never thought that alcohol would fix the issue. I used one if my wife's 'swabs' and it wasn't that dirty but must have been enough to stop the connection!

My buddy's father looked at it and couldn't figure the issue out and he was military and device tech doing radio stuff. After that I thought it was a complicated issue.


Maybe I can help you in the future as a payback. Or someone else will find this thread as there is not much out there in the scopemeters

Jeff

 

[Max Headroom]

Glad to help 😎.

Now you have a nice little tool.
You also know how to fix remote controls.

Dan.