Tech: Pinbot start up Failure - Fixed

[jebs...@gmail.com]

The Pinbot I am in the process of saving was failing to boot up
correctly. The displays would show one digit correctly (middle digit
on both left and right alpha displays - "T" from "Factory Settings")
and the game would go into attract mode, talking, GI but no controlled
lamps. Game would not coin up. MPU was showing solid 5 volt led,
blinking diagnostic led, and blanking led off. Replaced U43 (555
timer) and Q50. No Change. No output to output leg (3) on U43.
Jumping input leg (8) to signal (7) would result in blanking led
coming on and proper voltages elsewhere.

Checked capacitor C58, found bad, replaced. Game now operates.

Replaced thus far on this game:

Wiring harness, all three bridge rectifiers, and transformer. I added
the fuses to avoid a repeat of the main failure. Still needed,
displays (outgassing). Of course I will have way more time and money
in this than it is worth when done, good thing I do this for
enjoyment.

Thought I would post the fix in case anyone else encounters a similar
problem.

jeb

[someotherguy]

Thanks Jeb; there's a real lack of good tech posts anymore and it's nice when
people post their repair logs. I don't have my schems in front of me, but C58 -
is that in the blanking section, since you were concentrating on that area?

I guess I missed your previous post; did this machine suffer a BR short and
associated wiring burn, hence your addition of the fuses?

Richard

[jebs...@gmail.com]

Richard,

I bought this machine sight unseen. When I got into it I discovered
that it had indeed had a shorted bridge rectifier event. Which took
out the wiring harness and the transformer. I replaced them and added
the fuses for protection against a recurrence.

The C58 is the larger cap (relatively speaking) in the blanking
circuit, adjacent to Q50 and U43. The game behaviour was strange as
the MPU would actually boot and enter an abbriveated attract mode with
the display acting strangely and no controlled lamps. You could turn
it on and the machine would boot up and begin talking as it normally
would in attract mode.

My suggestions to anyone whose system 11 mpu blanking led fails to
light would be to replace U43, Q50 and C58 at the same time, all cheap
components.

This game also had 1251 bulbs in places meant for #89's. Which
evidentally melted the wire for the associated resistor off under the
playfield, causing the lights to not work.

jeb

On Jun 23, 3:02 pm, someotherguy
<someotherguy@SPAM_SUCKSsomeotherplace.com> wrote:
> On Sat, 21 Jun 2008 14:51:36 -0700 (PDT), "jebsfo...@gmail.com"

> Richard- Hide quoted text -
>
> - Show quoted text -

[someotherguy]

On Mon, 23 Jun 2008 18:19:54 -0700 (PDT), "jebs...@gmail.com"
<jebs...@gmail.com> wrote:

>Richard,
>
>I bought this machine sight unseen. When I got into it I discovered
>that it had indeed had a shorted bridge rectifier event. Which took
>out the wiring harness and the transformer. I replaced them and added
>the fuses for protection against a recurrence.
>
>The C58 is the larger cap (relatively speaking) in the blanking
>circuit, adjacent to Q50 and U43. The game behaviour was strange as
>the MPU would actually boot and enter an abbriveated attract mode with
>the display acting strangely and no controlled lamps. You could turn
>it on and the machine would boot up and begin talking as it normally
>would in attract mode.
>
>My suggestions to anyone whose system 11 mpu blanking led fails to
>light would be to replace U43, Q50 and C58 at the same time, all cheap
>components.
>
>This game also had 1251 bulbs in places meant for #89's. Which
>evidentally melted the wire for the associated resistor off under the
>playfield, causing the lights to not work.
>
>jeb

Cool; I figured that's where you would have been working. Also cool in terms of
reference, at least - this is the 2nd case I've seen of BR shorts causing
damage, the other being U.K. Dave's Varkon, pics of which are featured in Clay's
guides as the reason behind adding the BR fuses.

I've modified ALL my older games to fuse the BR's, with some small amount of
ridicule from a couple of dorks I know that think it's not needed, as the
likelihood of failure is very small. That may be, but the likelihood of extreme
damage from that failure is very high. It's a cheap, easy mod; protection that
is worth far more than the cost of parts or investment of effort. And MUCH
cheaper and easier than repairing the damage that it can prevent.

What's funny about yours having 1251's in place of 89's is I usually find the
exact opposite. 89's in place of 1251's, and they've blown out so
catastrophically that the filament plated the inside of the bulb, turning it
silver. : )

Richard