Urgent Help Please Circuit Design 555 Cd4017

[spec]

CORRECTION

Put a 100R or near resistor in series with the meter leads and switch the meter to 100mA DC and measure the current at pin 7 of the 555. The other meter lead connects to the 0V line

 

[Keshin]

ok kool that may have been my fault im not sure if i did that when testing or something. so how do i test there is no short?

 

[Keshin]

haha you beat me to it ok ill test now

 

[Keshin]

ok i feel a little dumb which setting is that sorry

 

[spec]

UPDATE

200m, bottom left. The reading should be zero to about 3; very low!

 

[Keshin]

i only have a 200r resistor, trying that i came with the following
i wasnt sure if i needed to do it powered up or not so i did both
unplugged 0
plugged in 31.7

 

[spec]

OK. There is a short between pin 7 of the 555 and the 6V supply line.

Remove pin 7 of the 555 from the circuit and do the same measurement, either at the bottom of the 2K7 pull-up resistor, or pin 14 of the 4017. The meter should read between zero and around 3

 

[Keshin]

okay disconnected pin 7 on 555 now my reading is 02.2

 

[spec]

That is an OK reading. Now connect a wire between pin 3 of the 555 and pin 14 of the 4017 or bottom of the 2K7 pull up.

Set the meter to 20 (top right). You should see a voltage swinging between 0V and 6V at pin 14 of the 4017.

(Best keep checking in case I update my posts)

UPDATE
Pin 7 of the 555 should not be connected to the circuit again. That output is blown.

 

[Keshin]

ok i think i got something more wrong with that chip (i do have another though from the first circuit as i bought a new one today for this one)

i did a reading with pin 3 (555) attached to pin 14 (4017) reading fluctuated between 3.2 and 3.4

i removed it again and tested pin 14 on the 4017 and the it read 6.4 (nothing connected other than the resistor to pin 14)

i then tested the 555 pin 3 without pin 14 attached and the reading is the same as when connected to pin 14

 

[MrAl]

Tick, tock ... tick, tock ...

 

[spec]

That does not make sense- the circuit not you. Are you sure you measured on pin 3? It sounds like pin 4.

UPDATE

You have removed the 200R resistor and switched the meter to 20V

 

[spec]

Tick, tock ... tick, tock ...

Remote control

 

[Keshin]

definitely measured on pin 3 ill try and draw up a quick circuit of the other board and maybe you could see if its close and what changes i need to make? if you dont mind. it will only be in paint tho.
maybe i did something with a chip on this board

edit: actually i will redo the board and get back to you thanks

 

[spec]

Keshin, stay with this board for the time being. We will soon get to the problem. Don't keep thinking you have made a mistake.

Are you sure you switched the meter to 20V (top right in your picture)

 

[Keshin]

yes definetly on 20v

 

[Keshin]

could this be related to the trim pot?

 

[spec]

Good move. hope you didn't mind me checking.

This is how I see it. The present 555 is toast.

Can you fit a new one, but leave pin 7 disconnected.

Connect the negative lead of the meter to the 0V supply line. Switch the meter to 20V and check that pin 3 of the 555 is swinging between 0V and 6V.

Don't rush. Take your time. Have a beer or a coffee.

Let me know how it goes

spec

(PS: weather you have made a mistake or not is not relevant- I make mistakes all the time, and I have a mountain of blown components, especially loudspeakers to prove it. The only way to avoid mistakes is to avoid doing anything )

 

[Keshin]

haha thanks ok i will switch out the 555, leave pin 7 disconnected and test, but first its definetly time for a coffee. should have it done in about 30 mins

 

[spec]

Good move

Don't worry about me. I have more than enough things to do. Your posts are no inconvienience whatever!