Slightly of topic tech question

[John Bennett]

[ukvac] Slightly of topic tech question
Hi all

Can any one help me, I have a pinball machine that seems to do strange
things when lots of power is consumed. I will attempt to install an
additional 5v regulated PSU to supply the troublesome board only.

Can anyone confirm whether or not I can use a standard PC PSU 5v out put and
just common the 0v?

Many thanks

Biff

PS Before I get any flames yes I have tried the pinball group;-)
PPS "D-Z" the answer is Peterborough, sorry I am late.

-------------------------- eGroups Sponsor -------------------------~-~>
eGroups eLerts
It's Easy. It's Fun. Best of All, it's Free!
http://click.egroups.com/1/9698/1/_/5935/_/976388959/
---------------------------------------------------------------------_->

DATA Imported from archives: originally posted by Biff (boffbiff@hotmail.com)

 

[John Bennett]

Re: [ukvac] Slightly of topic tech question
In article <OE49euUiUrYvf5RU2li000075ee@hotmail.com>, Biff
<boffbiff@hotmail.com> writes
>Can any one help me, I have a pinball machine that seems to do strange
>things when lots of power is consumed. I will attempt to install an
>additional 5v regulated PSU to supply the troublesome board only.

This sort of thing happens when the PSU smoothing caps start drying out
and you get excessive ripple on the line. The extra load pulls this
ripple down into the realm of CPU crashing.

Another common problem is diode failure in the bridge rectifiers meaning
that the system is only getting half wave rectified DC anyway. These
faults are easy to detect with a scope, but putting a digital meter set
to AC across the DC supply will show the level of ripple.

--
Clive Mitchell

-------------------------- eGroups Sponsor -------------------------~-~>
eLerts
It's Easy. It's Fun. Best of All, it's Free!
http://click.egroups.com/1/9699/1/_/5935/_/976415952/
---------------------------------------------------------------------_->

DATA Imported from archives: originally posted by Clive Mitchell (clive@emanator.demon.co.uk)

 

[John Bennett]

Re: [ukvac] Slightly of topic tech question
> <boffbiff@hotmail.com> writes
> >Can any one help me, I have a pinball machine that seems to do strange
> >things when lots of power is consumed. I will attempt to install an
> >additional 5v regulated PSU to supply the troublesome board only.
>
> This sort of thing happens when the PSU smoothing caps start drying out
> and you get excessive ripple on the line. The extra load pulls this
> ripple down into the realm of CPU crashing.
>
> Another common problem is diode failure in the bridge rectifiers meaning
> that the system is only getting half wave rectified DC anyway. These
> faults are easy to detect with a scope, but putting a digital meter set
> to AC across the DC supply will show the level of ripple.
>
> --
> Clive Mitchell
>
Clive, I suppose I will have to replace all caps on PSU to be sure, as they
aren't the easiest buggers to test in circuit.

The above might also explain why some switches operate intermittently when
they are struck and my phantom tilting, even when the plum bob is removed;
hmmm thanks mate your a star.

I did manage to sort the flipper problem out by putting a 60nf cap in
parallel with the switch.
I had better look at the PSU and order some caps.

Cheers

Biff

-------------------------- eGroups Sponsor -------------------------~-~>
eGroups eLerts
It's Easy. It's Fun. Best of All, it's Free!
http://click.egroups.com/1/9698/1/_/5935/_/976484523/
---------------------------------------------------------------------_->

DATA Imported from archives: originally posted by Biff (boffbiff@hotmail.com)

 

[John Bennett]

Re: [ukvac] Slightly of topic tech question
In article <OE2707txagXBtgCQNmw00008054@hotmail.com>, Biff
<boffbiff@hotmail.com> writes
>Clive, I suppose I will have to replace all caps on PSU to be sure, as they
>aren't the easiest buggers to test in circuit.
>
As I found out the hard way, testing caps with a capacitance meter is
pretty useless for other than the most severe faults. The best way to
test capacitors is to use an ESR meter (Equivalent Series Resistance),
but as these are quite expensive, it's cheaper just to change all the
significant caps. (Which may look suspiciously smaller these days.)

>The above might also explain why some switches operate intermittently when
>they are struck and my phantom tilting, even when the plum bob is removed;
>hmmm thanks mate your a star.
>
If it's an old Bally, then the capacitors soldered across the switch
contacts give a lot of odd problems on the matrixed switches. If in
doubt try cutting the parallel caps off the switch contacts, since it
doesn't really affect game play much. The caps often cause problems
when you give the table a good clean, as the cleaner often creeps into
the caps.

For serious misreading of switches and possible "slam" resets, try
checking for shorted switches around the playfield by doing a switch
test and also doing a physical test. Sometimes if a switch or matrix
line is shorted to ground, some genuine switch closures may be read as a
slam. A prime candidate for this might be loose hardware on the coin
door resting on a switch contact.

--
Clive Mitchell

-------------------------- eGroups Sponsor -------------------------~-~>
eGroups eLerts
It's Easy. It's Fun. Best of All, it's Free!
http://click.egroups.com/1/9698/1/_/5935/_/976491179/
---------------------------------------------------------------------_->

DATA Imported from archives: originally posted by Clive Mitchell (clive@emanator.demon.co.uk)

 

[dz1n3]

Re: [ukvac] Slightly of topic tech question
Mitch (and anyone else interested!)

> As I found out the hard way, testing caps with a capacitance meter is
> pretty useless for other than the most severe faults. The best way to
> test capacitors is to use an ESR meter (Equivalent Series Resistance),
> but as these are quite expensive, it's cheaper just to change all the
> significant caps. (Which may look suspiciously smaller these days.)

I used to think that too with the cap meter i got, untill oneday i realized
that removing the cap from the chassis actually cured most caps cause of the
heat generated in the iron warms the cap up and makes the oil live again.
but if ya leave the cap standing for a while then test it then ya find its
faulty, another way i use too when i got time is wack the cap on the scope
using those component testes for it and that shows it up every time!

-------------------------- eGroups Sponsor -------------------------~-~>
eGroups eLerts
It's Easy. It's Fun. Best of All, it's Free!
http://click.egroups.com/1/9698/1/_/5935/_/976555647/
---------------------------------------------------------------------_->