Re: A/R II voltage running up

----- Original Message -----
From: "William Boucher" <boucher@mnsi.net>
To: <vectorlist@vectorlist.org>
Sent: Sunday, March 22, 2009 10:09 PM
Subject: Re: VECTOR: A/R II voltage running up

> The 0.1 ohm 7W resistor (R24) is not the issue. It likely looks like it
> is reading high due to the multimeter lead resistance. Hold the leads
> together and read that value (call that the zero value), then read across
> the resistor and subtract the zero value.

That makes sense... I get .2 to .3 ohm touching the leads together. Oh
well, Mouser gets more of my money and I'll have some spares. Never thought
the meter leads would get me. I'll definitely remember that next time.
>
> Obviously enough power is getting through R24, in fact, too much. Check
> first R29 and R30, the 10 ohm, 1/2W resistors. They are what fail most
> commonly due to bad edge finger contacts (they burn).

Both were fine. In fact, the kit comes with a new R30.
>
> Another possible and probable problem could be that either Q2 (TIP32) or
> Q3 (2N3055) is shorted such that the regulator IC cannot turn down the
> output voltage because one of them is leaking.

Replaced both of those from the kit. Both originals tested ok, tool.
>
> If those parts are okay, check that the sense leads are okay (J7 pin 3 for
> +5V & pin 2 for gnd). Next check R7 (7.5k) and R6 (3.9k). These two
> resistors in series with 1k pot R8 control the regulator. Check R3 (33
> ohm) and R1 (270 ohm). I forget off the top of my head what they do for
> the regulator. It is entirely possibly that the LM305 regulator (Q1) is
> shot. Bob Roberts supplies them but hopefully it'll be something simpler
> than that.

All of those resistors check ok. The 1K pot tests out as well. I ordered
one of the LM305s just in case when I bought the connector kit. I might
have a socket...
>
> If the chips on the main board were really running at 6V... then may the
> force be with you.

That doesn't sound encouraging... I've read some of the hacks out there
about disabling the sense lines. I'm not ready to do anything that drastic.
I'm getting the same voltage on the A/R board as the game PCB; 5.45vdc.
Won't go any lower. I did play a few games with the back of the game off
and it passes all tests. No burn marks or toasted resistors to be found. I
did run a couple of jumpers from the A/R to the game pcb and nothing
changed.

Some have stated that if the A/R board is powered up with nothing connected,
it will burn the resistors. From looking at it, I can't really see how. I
can see a switchmode p/s going wild
>
> William Boucher

Thanks a lot for the info!

Kirk Spradling
>
>
> ----- Original Message -----
> From: "Kirk Spradling" <kspradling@kc.rr.com>
> To: <vectorlist@vectorlist.org>
> Sent: Sunday, March 22, 2009 10:03 PM
> Subject: Re: VECTOR: A/R II voltage running up
>
>
>> Pulled one lead of ALL resistors on the +5vdc side and found that the
>> .1ohm 7watt 3% resistor is showing .45ohm resistance. Does this need to
>> be a wirewound resistor or will a ceramic work ok? I've seen several
>> different types, non-inductive is more expensive.
>>
>> Recommendations?
>>
>> Thanks!
>>
>> Kirk S.
>> ----- Original Message -----
>> From: "Kirk Spradling" <kspradling@kc.rr.com>
>> To: <vectorlist@vectorlist.org>
>> Sent: Sunday, March 22, 2009 4:16 PM
>> Subject: VECTOR: A/R II voltage running up
>>
>>
>>> Hi,
>>>
>>> Rebuilding my Tempest P/S after noticing the voltage was at 6.05 volts.
>>> Attempted to adjust it and could only get down to 5.4vdc. Installed the
>>> Bob Roberts shotgun repair kit, big blue replacement, new pcb and
>>> harness connector kit and am still having the same issues. Measuring a
>>> voltage drop of about 0.125 on the +5vdc from P/S to Game PCB and less
>>> than .02 on the gnd. No burn marks on the pcb and edge connectors are
>>> in good shape.
>>>
>>> Who knows anything about looking for issues in the feedback system?
>>> Should I just start lifting resistors in the feedback area and taking
>>> readings to see if any have gone open? The pot does adjust the voltage,
>>> it just won't go down any further. Have tested all diodes on that side
>>> as well.
>>>
>>> Thanks,
>>>
>>> Kirk S.
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>>>
>>
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>
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Received on Mon Mar 23 00:04:43 2009