Core voltage test issue... nothing showing up!

Testing/Troubleshooting
1

Hi,

I am a newbie and not as smart as I thought so pease bare with me and my stupid issues. I have soldered the core and attached a universal regulated 9v ac/dc adaptor. But when I come to test with the multimeter i seem to be getting absolutely nada.

This is the front of the core:

Back of the core:

Multimeter Settings:

Soldering is not my trong point but at least something should be showing up no? So I must be doing something very wrong in the way I am testing or fried something. The thumbnail of the mutimeter shows the seeting I am using…is this correct?

I am testing on the front side as well as the back…which side should I be testing on?

In theory i should be able to connect the black cable to IC1:MCLR(1) …and the red cable on the multimeter to IC1:Vss(12) …and get 5V… and so on. At the moment I am getting nothing. Even if I sucked at soldering shouldnt I at least get some values at some points during the testing? Could I have toasted a component during soldering. If I use the multimer to check the power supply then that shows up as 9v.

Aso I dont really understand where the black cable on the multimeter should be positioned on the board for the tests in http://www.ucapps.de/howtodebug/mbhp_core_extract_measuring_vdd.gif

Thanks for all your input in advance…and dont worry I wont be quitting my day job : )

2

Hi,

In theory i should be able to connect the black cable to IC1:MCLR(1) …and the red cable on the multimeter to IC1:Vss(12) …and get 5V

Almost.

For the measurement you should fix the black cable to any ground/0V/Vss point. e.g. Ground on J2 or you hold the black cable on the metal case of the voltage regulator (there is also ground). With the red cable you should measure the locations mentioned in the pdf.

The only thing in your pictures I can see, is that the clamp of your “board holder” (don’t know the right word) is making a short. So please don’t measure the board, when it is clamped like in your pictures.

I am testing on the front side as well as the back…which side should I be testing on?

It doesn’t matter on which side you test. If no ICs are inserted, the upper side is more comfortable to measure. Just take care that you put the board on on a clean, non metal,  surface to avoid shorts on the back while testing.

greets

Doc

3

Thanks a lot for your input.

It is still not showing up with anything.  :frowning:

Could I possibly have shorted something as the silly me was testing out with the clamps on…doh!

Thanks

4

Please measure in the following order:

  1. Voltage on J1 - you should have something about 9V

if your power supply is AC the switch your multimeter to AC

  1. Voltage after the rectifier (B40C800) pins + und -. You should read about 7-8V

Switch your multimeter back to DC

  1. Voltage before and after the regulator. Put the black cable on the metal of the regulater and measure the left and the right pin of the regulator.

Still no voltage?

Please do this step by step and tell us at which point there is no voltage.

greets

Doc

5

Do you have a AC or DC psu? I cant see it really good on the pic, but J1 connected to ground isn’t it?? J1 should just go to the rectifier.

6

Hi,

The power supply I am using is a regulated 500mA AC adaptor at 9v.

  1. I have measured the voltage at J1 and get 9.10v.

  2. I am not entirely sure how to do step 2. Sorry for being dense, i seem to be losing hope.

I am getting nothing for step 3)

Any suggestions? Should I try and stuff a new core?

Again thanks for your input, i really appreciate it.

7
  1. I am not entirely sure how to do step 2. Sorry for being dense, i seem to be losing hope.

locate the round regulator.

Hold the black wire to the pin marked - and the red wire to the pin marked +. Now you should read about 7V on your meter.

if you you put both wires to the pins marked ~ , you should read 9V (from your powersupply).

If you measure 9V (at ~) and nothing at the output (+ / -) then your regulator is broken.

I think, you shouldn’t build a new core. Be patient and try to troubeleshoot your existing board. Step by step.

greets

Doc

8

hi,

Thanks for all your comments.

My conclusion thus far is that the rectifier has broken. I get nothing at ~, but 9v at the + -.

I am trying to get the component from maplins in th uk (B40C800)… does this look like the correct one?

W005M

http://www.maplin.co.uk/module.aspx?ITAG=SPEC&ModuleNo=46438&doy=25m4#spec

Thanks

9

Hi,

Getting nothing at ~ and 9V at + - does not make sense. It’s impossible to have something at the output if you have nothing at the input…

Are you sure you’ve set your multimeter in AC mode when measuring ~?

Have you set your multimeter in DC mode when measuring + -?

If so, then I would say that the rectifier is working OK. Then you could proceed with step3 as described by Doc. Maybe it’s the regulator that has gotten fried by the short made with the board holder.

Best regards,

Lall

10

Hi Lall,

yes I have set the multimeter to DC when measuring + - and get 9v, and AC when measuring ~ getting nothing.

Is the rectifier supposed to be installed onto the board in a certain direction? Could I have installed it wrong…

Thanks

11

Hi,

That’s really really strange.

Well indeed there’s a direction. The ~ should be connected towards the J1 and the + - towards the big capacitor.

When I look at the picture you’ve posted, it looks like you could have swapped ~ and +/-.

Best regards,

Lall

12

yeah yeah yeah!! i turned the rectifier the right way…and voila all is how it supposed to be…(fingers crossed, knock on wood)

measured the voltages at all the spots

IC1:MCLR(1) - IC1:Vss(12) = 5V

IC1:Vdd(11) - IC1:Vss(12) = 5V

IC1:Vdd(32) - IC1:Vss(31) = 5V

IC2(8) - IC2:(5) = 5V

and i have 4.94 at all of them…jubiiii!!!

I cant thank you enough for your help…me being so dense and all…absolutely brilliant…

until my next headbanging on the desk moment…

rock on \m/

13

Hey great news, congratulations  :slight_smile:

Good luck for the following steps…

Best regards,

Lall

14

;D Thats the feeling I always have after finishing a Core \o/ …makes addict  ;D