...I don't know if they got shut down or evicted or the guys that ran it retired and packed it in or what but they were the most child unfriendly nasty old farts you could've found. No free or cheaply priced scrap bits, no help, no nothing. They wanted top dollar for junk. After one or two visits including being sent down by my parents to get a free estimate on having the lawn mower repaired and being turned around when I didn't have the $30 nobody knew that this was going to cost to be estimated but I never went back on my own and my parents got the mower fixed elsewhere.
So what you're saying is... America doesn't have a monopoly on assholes...? ![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif)
mnem
"They may not have invented 'asshole'... but they sure are trying to perfect it."
No. America does not have a monopoly on assholes. Far from. There are more than enough to go round, that’s for sure.
So my planned analog meter session didn’t happen yesterday since I had to catch up on stuff around the house. One item was the thermostat. It got cold enough in here on Friday night that I climbed out of bed and went to put the heat on to take the chill off but the thermostat didn’t light up when I tapped the mode button. When I looked at it more closely after switching a lamp on I saw the display was completely blank so I thought ok, the batteries died, I’m not fighting with this right now and went back to bed since I could tolerate it. Anyhow, I get to test equipment time last evening and that reminded me of the thermostat so I changed the batteries out and got nothing. And that’s how the temperature sensing device on the living room wall bumped the antique multimeters down from the top of the list.
![Test Equipment Anonymous (TEA) group therapy thread 1070662-0](https://www.eevblog.com/forum/index.php?action=dlattach;topic=81471.0;attach=1070664;image)
![Test Equipment Anonymous (TEA) group therapy thread 1070666-1](https://www.eevblog.com/forum/index.php?action=dlattach;topic=81471.0;attach=1070668;image)
I decided to feed in three volts and change from a bench power supply and see if that made a difference but it was completely dead. Since it’s already broken I decided there’s nothing to lose by getting out a big flat head screwdriver and prying the casing open to take a look around and see if there’s anything obvious like a break in circuit where the battery terminals join the traces on the board, something subject to mechanical wear like that or obviously bulging caps, the works.
![Test Equipment Anonymous (TEA) group therapy thread 1070670-2](https://www.eevblog.com/forum/index.php?action=dlattach;topic=81471.0;attach=1070672;image)
Nothing really stood out other than all this surface mount stuff is about as far away from a bimetallic strip and mercury slosh tube as you can get. The Omron relays were a bit of a surprise as were the test points so I decided to power it back up and see if there was anything on the test points that might shed some light on what happened to this thing.
![Test Equipment Anonymous (TEA) group therapy thread 1070674-3](https://www.eevblog.com/forum/index.php?action=dlattach;topic=81471.0;attach=1070676;image)
![Test Equipment Anonymous (TEA) group therapy thread 1070682-4](https://www.eevblog.com/forum/index.php?action=dlattach;topic=81471.0;attach=1070684;image)
Five of the test points had the 3.2 V I was feeding in on them and the other was a touch under a volt so I thought about putting a scope on it and I caught a glimpse of the screen when I was rolling it around thinking about how I want to probe that one low test point to see if it’s got a clock pulse train for the digital stuff or something like that and I saw it had come up. Looking closer I could see the clip leads I had on it for power had slowly wiggles around and had revealed shiny metal on the battery terminals. They’d finally bit through a pretty thick layer of oxide and were finally making contact with good conducting metal. I honestly thought this was how the metal was finished but it was a thick layer of oxide. The fix for that’s simple, I got out a small file and cleaned the two terminals off and put the two batteries back in and reassembled the thing.
![Test Equipment Anonymous (TEA) group therapy thread 1070678-5](https://www.eevblog.com/forum/index.php?action=dlattach;topic=81471.0;attach=1070680;image)
Back on the wall and back in business. That was a lot less expensive than buying a replacement. It’s cheesy of Honeywell to be using a metal that develops surface oxide like this in a location exposed to the air where it eventually builds up enough that not even the voltage from a new set of AA batteries can punch through it even with the mechanical abrasion of removing the old ones and installing new ones. That’s a good way to make customers throw otherwise good thermostats out and go buy a new one...