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erratic readings on 2200uf capacitors on power board
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erratic readings on 2200uf capacitors on power board

by maxheadrush on Sun Jul 30, 2017 12:01 pm

Hi
i am having an issue at the very start of my build (xoxshop.de) as i am getting very strange readings from c4 and c5.

according the the build instruction you should read 15v over these caps but i am getting erratic readings that seem to just change all the time (possibly getting lower)

the guy didnt have the usual caps he supplys for these and sent me out what he had, (they are slightly larger than the normal ones) one is 16v and one is 25v, both are however 2200uf.

i have resoldered everything and i notice that the innermost pin of the power terminal seems to bridge with the leg of diode 42 is this correct ?

can anyone give me any advice or thoughts on this matter please ?
thanks in advance

maxheadrush
 
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Re: erratic readings on 2200uf capacitors on power board

by antto on Sun Jul 30, 2017 12:43 pm

when you measure the voltage on the AC adapter, it should show you ~9VAC and you should measure in AC voltage mode (on your multimeter)
for pretty much everywhere else on the x0xb0x, unless otherwise specified, you should measure in DC voltage mode

those four diodes form a weird rectifier, to make the AC voltage into DC
D42's anode should be connected to D41's cathode (the leg where the white line is), and that should be also connected to one pin on the barrel jack
on the other hand, D43's anode should be connected to D40's cathode, and that should be connected to the other pin on the barrel jack
you can check that with your multimeter in continuity mode (where it beeps when you touch the probes) when the circuit is not powered

antto
 
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Re: erratic readings on 2200uf capacitors on power board

by maxheadrush on Sun Jul 30, 2017 1:43 pm

Hi
Thanks for your help

I have resolved the issue, It was the on off switch needing shorting.

It is not mentioned in the build instructions so didn't even think of it until I found someone else had similar issues in the past.

maxheadrush
 
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Joined: Sun Jul 30, 2017 11:37 am

Re: erratic readings on 2200uf capacitors on power board

by antto on Sun Jul 30, 2017 3:09 pm

ah, yes
well, the x0xb0x doesn't have an on/off switch by design, some people modded it
but i think x0xsh0p.de have made a modified ioboard PCB which includes solder pads for an on/off switch

antto
 
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Re: erratic readings on 2200uf capacitors on power board

by maxheadrush on Sun Jul 30, 2017 3:48 pm

That's right but I think I spoke too soon, I am having another issue.

I am reading 9.5-10.5 v on ic20 (should be 5) and 9.5 -10.5 v on c6 (should be 5)

I have searched the threads and the only similar problem I can see is someone who soldered it in backwards, however I have not and I even reversed it anyway just to be sure and got the same readings.

Any suggestions on what could cause this anyone ?

maxheadrush
 
Posts: 4
Joined: Sun Jul 30, 2017 11:37 am

Re: erratic readings on 2200uf capacitors on power board

by antto on Sun Jul 30, 2017 4:00 pm

it could be busted
if you can, attach its input to a 9V battery and measure its output with a multimeter
in that setup, it should give you 5V
if it doesn't - get a new one
these are very common components, you should have them in your local electronic components shop

antto
 
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Re: erratic readings on 2200uf capacitors on power board

by maxheadrush on Sun Jul 30, 2017 4:38 pm

Thanks for the advice, I don't have a 9v battery but have found a replacement locally, seems to be the right part

http://www.maplin.co.uk/p/ts7805cz-1a-p ... case-ql31j

Cheers

maxheadrush
 
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Joined: Sun Jul 30, 2017 11:37 am

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