Ambika Port 7 Connection between the Green Point +5 Volt and GND

Dear Mutables,

as above you can read my problem. Please advise, thank you very much.

All the best,

waldemaR

I can well read but i don’t quite understand…

Dear Frank,

thank you very much for the quick reply.
On the side 15 there is the picture with Port 7 where you have measure a connection between different points. Also you have to measure between the green ( +5V ) and GND.
Between this two points i have a connection.

All the best,

waldemaR

So i assume you are building an Ambika Motherboard, and referring to this Pic, right?

While this might be perfectly clear to you - as you are sitting with the Mobo in front of you - it took a bit for me to think over what you mean…. at least at my browser no page numbers are shown, so would be helpful if you describe your problems a bit more extensively, next time.

For your Problem:

You have shorted the +5V and GND Rails which in general is a bad idea and will cause nonworking circuits and Overtemperature shutdown of 7805 regulators - or their death. This fault could be anywhere on the PCB. Flip over the board and look for any 2 solder joints accidentally connected, especially at all the 100N decoupling caps (where one pin is always Vcc and the other GND) and at the Display where Vcc and GND are neighbors…) Post a High Res Pic so we can have a look.

Can you measure the resistance between 5V and GND? Or do you mean: connection = 0 Ohm?

One question, regarding connection. It is correct that the regulator 7805 has between to legs a connection?

All the best,

waldemaR

Dear cj55,

i mean i have a connection that my measurement make a tone.

All the best,

waldemaR

No, theres no connection between any of the legs of the 7805. At least not in any reasonable setup as far as i can see, the data sheet points out or commonly used :wink:

If your meter “makes a tone” then your are not measuring Resistance, you are measuring continuity which might be well above the 0 Ohms a short would show. Set your meter to a low resistance setting (2k is perfectly suited) and measure again. If you get 0 Ohms you have a short.

If you are using a slightly cheaper meter, be aware of the fact that your probes have some resistance as well, easiest way to measure that is to touch the two probes to each other, remember this resistance, since it will be what a short will look like :slight_smile:

And you have to do your measurements (resistance or continuity) with power disconnected. Just to be shure…

double

Dear cj55,

i measure exactly 0.6 Ohm.
Picture i will later upload, because i have a really bad connection in the moment.
I’m at La Palma and have to go to a Internet Cafe.

All the best,

waldem

Dear Frank and All others,

that you want to help me very quick, thank you!

@Frank, next time i will write it more clear, sorry for the miss understanding.

Also sorry for the delay of the picture. I have a bad connection and have to go to a Internet Cafe to upload the pictures.

My measure problem is still there . But i remember that this happen the first time when i solder the IC7 7805. You can see attach where i measure 0.4 Ohm.

So the problem must start before.

Now what i can check for measuring?
I also check once again the solder, but nothing find.
Maybe i see something worng solder not.

Hopefully this help to find the problem.

All the best,

waldemaR

YOu are measuring the Output against GND, so the problem can be anywhere on the board. First step would be to cut the legs shorter, there are some very long ones, no need to have them longer than the solder point. Make sure you cut all of them, some of them mitt accidentally touch.

Dear Frank,

thank you for coming back.
I’m still at the cafe regarding Internet connection.
Can i do something else? before i leave :wink:

All the best,

waldemaR

Here are 2 Pics, i marked every spot i would inspect and possibly go over (cut lead, resolder)

Especially the Display Connector looks blurred, check there!

Dear Frank,

thank you once again.
I have a question regarding the Display connector. How many GND are located and where?

All the best,

waldemaR

Here is the Pinout and the List with the connections. PIN 1 is - if you look on the display, connectors to the left LOWEST ROW, RIGHT, Pin 2 is LOWEST ROW left and so on.

Note that Pin 7 (DB0) to Pin 10 (DB3) are not used

Dear Frank,

i will do best.
Result will follow.

First a nice Sunday in Germany.

All the best,

waldemaR