Re: Gottlieb System 80 Power Supply Voltage dropping with CPU


"Matt" <sirmistermatt@xxxxxxxxx> wrote in message news:ab4e5e70-5ba3-46ed-99b5-4b2d631140de@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Apr 24, 8:33 am, Matt <sirmisterm...@xxxxxxxxx> wrote:
On Apr 20, 3:01 pm, "Dan Beck" <biscuitbecks@*nospam*cableone.net>
wrote:



> "Steve Charland" <ccharl...@xxxxxxxxxxx> wrote in message

>news:7LydnUmzl9N04JbVnZ2dnUVZ_judnZ2d@xxxxxxxxxxxxxx

> > Matt,
> > What's blinking? If it's the tilt relay only (turning off and on), > > then
> > you could have a bad game ROM or just need to reseat it. Make sure > > the
> > notch is up like everything else before plugging the CPU board in. If > > the
> > notch is down, the game ROM is probably toast now and you could have > > other
> > issues on the board.

> > Steve
> >System80, not just a job, it's an adventure

> > Matt wrote:
> >> Dan,

> >> My backbox parts are completely taken off and disconnected, I just
> >> want to get the voltage to stabilize when I hook up the CPU and go
> >> from there.

> >> I did replace parts and, against good advice (and with the same
> >> curiousity that kills cats), I hooked it up again. This time instead
> >> of blink blink blink bliiiiiinnnkkk (dim) it just continuously
> >> blinked...

> >> In any event, I will be replacing the transistor and rebuilding my
> >> power supply as soon as I get my parts on Tuesday and will report
> >> back.

> >> Some of this might be highly unneceesary, but I'd rather just
> >> eliminate as many variables as possible.

> >> Thanks.

> >> Best,
> >> Matt J.

> Steve, I believe Matt is referring to the 5 volt LED on the power > supply
> board.

> Matt, certainly you want to eliminate variables by replacing old with > new,
> and in my opinion I think it is a good idea in the long run, although > Clay
> the gospel speaker does not think so... :-)

> Please do not forget you have corroded items on your control (cpu) > control
> board. Once you solidify your power supply, when you power up that > control
> board with corrosion the possibility exists that you could still see a
> voltage drop, although in my experience it is not common. I think > while you
> are waiting for power supply parts you should complete that control > board.
> I remember seeing pictures of that board; it is no small undertaking > what
> you have to do to get that board clean, unfortunately!

> Once the control board is clean, and your power supply is known to be > solid,
> then a systematic approach (i.e., one at a time) to powering up the > boards
> in the backbox (as Clay and others have suggested) is a good idea.

> Do you own a logic probe? That is a handy tool.

> Regards,
> Dan

> ** Posted fromhttp://www.teranews.com**

Guys,

OK I replaced my Q3 on the power supply with a new one. Replaced CR5
per Dan at Great Plains' instructions, replaced C2 (which had rusty-
looking leads). Also socketed and replaced IC1 voltage regulator with
a new one.

Put the 5ohm 10watt resistor from test points COM to 5V test point. 5V
LED immediately dims to almost nothing. Was instructed by Dan in an
earlier post/thread to test it under a load like that.

Fixed my final corroded part on CPU, Z2, with a nice new socket and
chip. Just for curiousity's sake I powered the board, and it does the
same thing the resistor does: now the 5V LED doesn't even chug or
blink anymore, it just immediately dims.

I am going to swap out those bridge rectifiers for now until I get my
hands on a new C1, although I am fairly positive C1 is relatively new
(based on decent but clearly "aftermarket" soldering job done on it's
leads, which I haven't touched).

Thus far, I have replaced (according to pinrepair or Great Plains'
guidance):

Q3
C2
SCR1
POT1
CR5
R3
CR6
IC1

Any ideas if this rules out anything or changes directions for me?

For now, I am going to go ahead and change out those bridge rectifiers
and get my hands on a C1. I did already have the orange cap in the
cabinet replaced with a better-than-spec computer grade one.

Any ideas where to go after that, if need be?

THANKS GUYS for the help so far. I really appreciate it and am
enjoying this "adventure."

Best,
Matt

Oh and forgot to add: voltage at 5V test point with resistor load and
immediately dim 5V LED is still at around 1.5 V, same as when it would
blink and huff and puff and then dim.

- Matt

With this load resistor installed, make sure you do this with nothing else connected (CPU or driver or other loads such as displays). If this still happens with nothing else installed, then you have ruled out a short from the CPU board or other destination.

-- Ed


.

Relevant Pages

  • Re: Gottlieb System 80 Power Supply Voltage dropping with CPU
    ... I believe Matt is referring to the 5 volt LED on the power ... certainly you want to eliminate variables by replacing old with ... >> Please do not forget you have corroded items on your control ... > blink anymore, it just immediately dims. ...
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  • Re: Gottlieb System 80 Power Supply Voltage dropping with CPU
    ... > Matt wrote: ... >> of blink blink blink bliiiiiinnnkkk it just continuously ... Matt, certainly you want to eliminate variables by replacing old with new, ... Please do not forget you have corroded items on your control control ...
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