David Shoemaker wrote:
> Going to resurrect a VERY old thread here.
>
> The part I have a question about is:
>
> "There are more elegant procedures for troubleshooting this if you have the
> right test equipment, but without it, it would be faster to just replace
> these components in the order given. "
>
> So I have a tempest board with no X deflection. As far as I can tell there
> is either a dead AM6012 @ A10 or a dead TL082 @A11. I come up with this
> because there is no output at pin 7 of the Tl082.
>
> But I can't be sure because when I scope pin A11:6 (from A10:18 I get a flat
> line). But I also get a flat line on the equivalent signal on the Y side
> which is working fine.
>
> So anybody know just what the "more elegant procedures" are that Joel was
> speaking of here? I assume the DAC is current mode into the first stage of
> the op amp as such there is nothing for the scope to sense and display.
>
> Thanks,
> David
>
One rule of thumb I used when troubleshooting XY current mode games is
to look at the output voltage of each stage. If the device has +/-15VDC
supply, then the output should be 0VDC, if the device has a +5 supply
then the output is often 2.5VDC (not always).
I don't know if that will help, but it does somewhat nail defective
TL082s as well as the MC1495s - as I recall - its been a few years since
I last fixed a Tempest output stage.
John :-#)#
> -----Original Message-----
> From: owner-vectorlist@vectorlist.org
> [mailto:owner-vectorlist@vectorlist.org] On Behalf Of Joel Rosenzweig
> Sent: Wednesday, August 04, 2004 5:20 PM
> To: vectorlist@vectorlist.org
> Subject: Re: VECTOR: TECH: Tempest PCB
>
> Steve,
>
> The single line that you see is due to lack of deflection in the opposing
> axis. If the display shows a horizontal line only, then your vertical
> deflection circuit on the Tempest board is faulty. Because Tempest is a
> portrait mode oriented game, the axis are reversed, so you'd be looking at a
> "X" deflection circuit failure. If the display shows a vertical line only,
> then your horizontal deflection circuit on the Tempest board is faulty. And
> in this case, you'd be looking at the "Y" deflection circuit. On a
> landscape mode game, the "X" is horizontal and the "Y" is vertical. From
> the monitor's perspective, "X" is always horizontal and "Y" is always
> vertical, but this nomenclature is a little awkward when we rotate the
> monitor!
>
> The Tempest board has X,Y, and Z outputs. The "X" output is actually
> connected to the "Y" input on the monitor, and the "Y" output is actually
> connected to the "X" input on the monitor.
>
> The analog output section for each axis is made of a digital to analog
> converter and some op-amps. The likely scenario is that you have an op-amp
> failure after the converter. Give thought to replacing the TL082 (op-amp)
> first. If that doesn't work, replace the MC1495. And if that doesn't work,
> replace the AM6012 DAC.
>
> There are more elegant procedures for troubleshooting this if you have the
> right test equipment, but without it, it would be faster to just replace
> these components in the order given.
>
> Regards,
> Joel-
>
> ----- Original Message -----
> From: "Steve P." <projektzwo@yahoo.com>
> To: <vectorlist@vectorlist.org>
> Sent: Wednesday, August 04, 2004 11:26 AM
> Subject: VECTOR: TECH: Tempest PCB
>
>
>
>> Hi everyone.
>>
>> I have 2 Tempest PCBs that I could use some assistance with. I am NOT an
>> electronics guy, so my tech skills aren't great.
>>
>> The first one is working and playable. It has an odd habit though of
>> resetting for no appearent reason. This usually happens in the red or
>> yellow tubes. Game will be playing right along and ZAP! resets and goes
>> into attract mode. I've swapped AUX boards, reflowed solder on the
>> interconnect cable connections, swapped ROMS sd well as the other socketed
>> chips and still get the odd reset... Any ideas?
>>
>> Board number 2 has a graphics issue. PCB coins up and plays but the
>>
> display
>
>> is squished into a bent line. Checked the vector trimmer pots and they
>>
> seem
>
>> ok. Also did the same swapping of parts on this PCB that I did on the
>> first. LMK if anyone would like a pic of the screen.
>>
>> Thanks in advance!
>>
>>
>>
>> -Steve P.
>>
>>
>> --------------------------------------------------------------------------
>>
> -
>
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>>
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>
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--
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
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"Old pinballers never die, they just flip out"
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Received on Mon Nov 23 02:14:09 2009
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