r/alarmdotcom • u/myrhillion • Sep 13 '26
Help ADC-VDB750 failed.
Hello, I have a guardian system that came with the house/builder, it uses the ADC-VDB750. I think this summer heat did mine in, as it just failed (just about 3 years old). I'd had to reset it a few times over the last month as well, but it's been exceptionally hot in NC this summer. Now it just seems completely dead.
Looking at replacing with ADC-VDB775. Anything a layman homeowner should consider around this replacement? Any wiring difficulties to consider? I'm hoping it's just a pop/swap and add it to the guardian app, if that's possible.
If it's not the camera but a power issue, I have a voltage meter or could even try an older ring camera I have from the old house I could use as a test.
Thank you!
2
u/tamreacct Sep 14 '26 edited Sep 14 '26
Check doorbell transformer output voltage or marking indicating current, as home builders usually install the lowest output transformer.
Get something that can handle smart doorbells with extra capacity such as a 30VA-40VA minimum.
EDIT: make sure to check behind chime box if you can’t find it anywhere.
As for pop and swap from 750 to 775, they use different mounting bases.make sure you take a picture of how the wiring path is placed to ensure it if it’s properly and makes contact to the terminals.
If you’re buying used unit, make sure seller has removed/unregistered device from their account. Otherwise you’ll get frustrated resetting it and it continues to fail during connection to panel via app.
1
u/myrhillion Sep 14 '26
Ooh, added the check behind chime box for the transformer location. Might make that easier to change if it's not sufficiently (30VA-40VA that you suggest). I'll go new vdb if I do need it after checking the voltage/transformers and at door bell wiring. Thanks so much!
1
u/tamreacct 27d ago
Transformer is $20 and best to ensure it has enough current output before purchasing a new camera.
I have suggested this in the past when someone couldn’t find it and guess where they found it. Just get a 24VAC 40VA from homedepot for $20!
1
u/tamreacct 26d ago
Also you can plug vdb750 into USB port on back to see if it connects and works. No need to remove the standard backplate, just the doorbell.
1
u/Jluke001 Sep 13 '26
Did you check your doorbell transformer?
1
u/myrhillion Sep 14 '26
nope, added to the checklist before I buy a new vdb. I think it may be very hard to find, probably way up in the crawlspace... have to go get uncomfortable to see about this one, lol. Assume a voltmeter is all I'd need to bring (as if it is the doorbell transformer, I'm not even sure how to replace).. would likely call our local electrician at that point.
1
u/Jluke001 Sep 14 '26
Check under stairs, behind the dead front of your panel, behind the door bell chime, right within the attic access, places like that
1
u/Arnix1 Sep 13 '26
It's a simple replacement to the 775, I've noticed over the last few months that the battery expands in the 770 and that's when it starts having issues. Check and see if the battery on yours has expanded or not, it is under the information sticker when you remove the doorbell from its base.
2
u/realdlc Sep 13 '26
As far as I know, the VDB750 does not have an internal battery. Neither does the VDB775.
1
u/tamreacct Sep 14 '26
Correct. No battery in the 750.
1
u/myrhillion Sep 14 '26
thank you!
1
u/tamreacct 28d ago
Hopefully you change the transformer as I had this same type of issue in the past. Even if it’s still working and under rated, a new higher current one costs about $20 for the part.
1
u/myrhillion 28d ago
I most likely will. This is what the alarm.com site has for recommended spec in my scenario: 16-24 VAC, 10-30 VA (16 VAC, 10 VA recommended).
As I'm not quite sure what mine is providing already, will have time to test the wires at the door over the weekend. If it's reading like 11.5V or so, I'll just replace it and bring everything with me for the 100' low crawl I have to do in the crawlspace to replace the doorbell transformer.
Appreciate the advice.
1
u/tamreacct 26d ago
Recommend is bare minimum requirements…just think of when installing software or Windows on a computer.
1
u/No-Explanation-2652 Sep 14 '26
Make sure you go 30 Amps. Best decision ever. 10 amp power at 16Vac is not enough. It's the minimum.
1
u/myrhillion Sep 14 '26
As a non-electrician, not even sure how to check this beyond voltage, amp check at the door. Thx!
1
u/davsch76 Sep 14 '26
It’s a very easy swap but I would explore whether there may be something going on beyond a bad doorbell
1
u/myrhillion Sep 14 '26
Thanks, I'll do a voltage and amp check on both the door wires and check the transformer before I replace the VDB (if I can find the transformer.. probably WAY up in the crawlspace...).
1
u/myrhillion Sep 14 '26
Just wanted to thank everyone for giving me solid things to think about. Hopefully I'll get the checks done over the next week and weekend.
2
u/realdlc Sep 13 '26
Volt meter is the way to go. Both the 750 and 775 will require solid power - If AC (which usually it is) it needs 16-24 VAC @ 10-40 VA. Check the specs of your transformer as well just to be sure.
If you do swap from the 750 to the 775, it is fairly simple, but if you have a mechanical chime, the 775 comes with a small module you need to install at the chime itself. (You might have a capacitor there from the 750 install, if so, that can be removed at that time.). That's about it for the physical installation. Of course you'd have to remove your 750 from alarm.com and add in the 775 as well.