Strange behavior? Ground Q1 back and clock shuts off. Classic Clock.

More
2 years 6 months ago #8388 by piercedfreak
LED1 is lit. The 7805 no longer gets hot, so I am guessing it is bad, but what else is bad too is my main concern.

Please Log in or Create an account to join the conversation.

More
2 years 6 months ago #8389 by Ty_Eeberfest
Take a look at the schematic. If the 7805 was bad it's highly unlikely that LED1 would be lit. If 7805 failed open the LED would get no power. If 7805 failed shorted the LED would get the full VIN voltage so it would probably light up quite bright. This is all speculation of course, the real test is to read VCC, if it's 5 volts the 7805 is okay. As for why the clock would not work if VCC is 5V, there are a multitude of possibilities.

Look into it later when the dust is clearing off the crater.

Please Log in or Create an account to join the conversation.

More
2 years 6 months ago #8394 by piercedfreak

Ty_Eeberfest wrote: Take a look at the schematic. If the 7805 was bad it's highly unlikely that LED1 would be lit. If 7805 failed open the LED would get no power. If 7805 failed shorted the LED would get the full VIN voltage so it would probably light up quite bright. This is all speculation of course, the real test is to read VCC, if it's 5 volts the 7805 is okay. As for why the clock would not work if VCC is 5V, there are a multitude of possibilities.



Point me in a direction, I have multimeter, and am not afraid to use it. All resistor, and diodes show correct value, so my next guess is the 328P.

Please Log in or Create an account to join the conversation.

More
2 years 6 months ago #8399 by Ty_Eeberfest
I'm also leaning toward the Atmega being damaged. I think I remember you having built some of these kits before now so I'm guessing you have programmed chips on hand. I'd try a swap-out now if it was me... but a few things to check on before going and (maybe) blowing up another Atmega:

First, for clarity: when I say "check for ground" I mean put + probe on a VCC testpoint and - probe on the thing you're checking. (Putting - on a ground testpoint and + on the point you're checking doesn't cut it)

Pull the suspect Atmega out of the socket and put aside... turn on power.

Check for +5 on pins 1, 7 and 20.
Check for ground on pins 8 and 22.
Pin 13 should be "floating" - definitely not grounded.
Pin 24 should be 1.5-ish volts (if you have the LDR connected) and 5v (if no LDR)

If that all checks out then try a known good Atmega if you have one.

Look into it later when the dust is clearing off the crater.

Please Log in or Create an account to join the conversation.

More
2 years 6 months ago #8400 by Ty_Eeberfest
Not sure of your level of experience, sorry if this is stating the obvious:

When you check for ground as I just described, you will read 5v on the meter if ground is present, and basically nothing on the meter if not grounded.

Look into it later when the dust is clearing off the crater.

Please Log in or Create an account to join the conversation.

More
2 years 6 months ago #8403 by Ian
Just jumping in here: In general, the TO220s need to be insulated if they are heatsinked. That usually means a little mica plate, and an insulator for the screw.

The other thing people try to do it heatsink both the TO220s on the same heatsink because they happen to be close to easch other. That's also a no-no.

I'm surprised grounding the TO220 didn't take out the power supply or the protection diode.

Could you make a quick video of the problem? Both with the controller in ad the controller removed?

Please Log in or Create an account to join the conversation.

Moderators: AccutronTy_EeberfestIan
Time to create page: 0.174 seconds

Search

Tube Suppliers

Go to top
JSN Boot template designed by JoomlaShine.com