power problems - finished but not working xoxbox (willzyx kit)

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cleaninglady
 
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Joined: Thu Jun 14, 2012 6:33 am

power problems - finished but not working xoxbox (willzyx kit)

Post by cleaninglady »

Hi All

Great to find this place and i hope i can learn a thing or two in the build process.

I bought a 'finished' willzyx kit that doesn't work.It came with the XOXBOX build manual and full BOM's

I started going over the boards. Noticed the main board had the two 2SA733P missing in the VCA so i whacked those in.

Nothing else seemed to be missing so i started from Power Supply.

I went through and got as follows :

Power Supply input voltage : 9.3VAC (seems a bit low) , i'm running a 110V /9VAC Wart on a 240V Stepup Transformer.

C3 - C5 : 29VAC (seems high)
7805 Left Pin to Ground Ref (Rear of 7805) : 4.97VDC
C1 to Ground Ref (same from here on) : 5.95
#5 Pin IC23 : 5.31 (Before Trim)
VCO REF : 5.33 (After Trim > TM6)
+12V Supply : 11.91

All seemed hunky dory so i went on to the VCO.

Connected J4 to main board

It seems when i used the 3v applied to the VCO Circuit to test something has gone amiss.

Couldn't get to my Oscilloscope , (i'm not too good on it anyway) so i tried the DC Offset test and that was way off.

I went back to the Power Supply and suddenly :

#5 Pin on IC23 : 2.3VDC
VCO Ref : 2.3
+12V Supply : 5.25

I checked every pin of IC23 and got the following.

1 : 5.25 VDC
2 : 2.3
3 : 2.3
4 : 0
5 : 2.3
6 : 2.3
7 : 2.3
8 : 27

Not too sure how to proceed. :oops:

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aminoacid
 
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Joined: Tue Jun 20, 2006 5:27 am

Re: power problems - finished but not working xoxbox (willzyx kit)

Post by aminoacid »

hi ckeaninglady!

so you have a voltage converter before the 9v adapter? cant you just use an adapter for your country?

look for ic´s and transistors getting real hot.

check resistance on j4 both with mainboard connected and not connected.

also check that all parts are correct and not backwards mounted.

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altitude
 
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Re: power problems - finished but not working xoxbox (willzyx kit)

Post by altitude »

Do the voltages come back after you unplug J4? If so, you have a short on one of the analog power lines. Check the resistance on the mainboard between 5.33 and GND and +12 and GND

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cleaninglady
 
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Joined: Thu Jun 14, 2012 6:33 am

Re: power problems - finished but not working xoxbox (willzyx kit)

Post by cleaninglady »

Just to be clear before we go on ; i have a fully assembled Power supply board and mainboard , i bought it 'not working'. Working through with the xOxbOx Build Manual.

-----------------------------------------------

Thanks for the replies , people ! :D


The voltages above (first post) are from IC #23 of the power supply with J4 unconnected to main board. Ground Ref : Metal rear of 7805 for all readings.

Resistances from the J4 (with Wall wart disconnected from Power Supply Board) :

J4 Pin 1 : Can only read on 2Meg setting on DMM , on contact climbs slowly over maybe 10 seconds from 0 up to 1.9999 Meg then nothing.

J4 Pin 3 : 4K

Can't get a reading at all from either Pins with Wart connected to Power Supply Board. (I'm not sure whether this is how i should be testing it ; powered or not , i mean).


On the main board - (Raeding from Mainboard J4 header to GND Ref as above , tested with VR2 Centred , no power from wart) :

J4 Pin 1 : 7.6K

J4 Pin 3 : 2.69K

Hope this is accurate enough.

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altitude
 
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Re: power problems - finished but not working xoxbox (willzyx kit)

Post by altitude »

cleaninglady wrote:--->J4 Pin 3 : 4K<--------
That sounds like it may be the problem. Pull that pin out and power it up again and see what the voltages look like at J4 (on the i/o board)

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cleaninglady
 
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Re: power problems - finished but not working xoxbox (willzyx kit)

Post by cleaninglady »

I desoldered Pin 3 wire , Voltage at Pin 3 is still 5.25 powered up , pin 1 still 2.35 as before.
In that state , Pin 8 on IC#23 has changed to 26.6 (a little lower)

Main board resistance (with J4 connected and pin 3 wire desoldered , no power) :

Pin 1 : 7.81K

Pin 3 : 8.31K

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mmm
 
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Re: power problems - finished but not working xoxbox (willzyx kit)

Post by mmm »

What are the voltages (against ground) on either side of R3?

Does TM6 cause any reaction at all; does the voltage on Pin5 change?

As far as the ground reference does: First check if you have continuity between the metal rear of the 7805 and pin 4 of IC23. The 7805 is connected to its own "digital" ground which in turn is connected to the analog ground just at a single point (the through-plating at C4).

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cleaninglady
 
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Joined: Thu Jun 14, 2012 6:33 am

Re: power problems - finished but not working xoxbox (willzyx kit)

Post by cleaninglady »

I'm a little saddened and embarrased to say i gave up and am sending it off to get it looked at by James (willzyx). :oops:

I'll be back when it's going and will be sure to hassle many of you about mods !

It was just too hard to do this with an already built machine. If i would have built it from the start maybe it would have been easier.

Thanks all and i'll let you know how it goes.

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