Re: Anyone have any troubleshooting advice?

So Tony... did you fix it??? If no, I have several ideas for you...

0. Flat-Hand-on board technique, check for hot components around the
vector chip area - careful, no rings on fingers !!
1. Check the latches/shift registers that feed the DAC. (Assuming that as
you said you have already elimintated the DAC and socketted it)
2. Check the op-amp following the DAC
3. Check the semiconductor switch 13201/DG201across the integrator op-amp
4. If necessary isolate and then ignore the sample-hold window clipping
amplifiers, by removing feed switch IC (you don't need window clipping to
get the board working). If you get it working, then 5. Check the normally
non-conducting op-amp input protection diodes on the window clipping
circuit as well as the comparator op-amps.
6. Check the voltage buffer output amps and their inverting switches...
7. Check that the integrating capacitor is not shorted or connecting with
groundplane.

I had one Battlezone board with everyone of the above problems, ie, every
chip in the chain and even one of the input protection diodes!!
Definately socket everything you remove.

Any good? Need details, get in touch...

- Tim.

PS: Sorry, don't have tempest schematics for details, but assuming that
Battlezone sufficiently similar to Tempest in Analog output area...

Tony Jones <tony@tonyjones.com>
Sent by: owner-vectorlist@synthcom.com
09/02/03 20:41
Please respond to vectorlist

 
        To: vectorlist@synthcom.com
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        Subject: VECTOR: Anyone have any troubleshooting advice?

I figured I'd be swimming in responses from this list? No ?

Regardless, if anyone has any advice I'd appreciate an e-mail.

> Date: Tue, 04 Feb 2003 00:30:02 PST
> To: vectorlist@synthcom.com
> From: Tony Jones <tony@tonyjones.com>
> Subject: VECTOR: tempest AVG troubleshooting help needed
>
>
> Hi.
>
> Hoping someone can help me. I'm trying the standard "trace the signal
back"
> methodology without much luck.
>
> Have what I think is a Tempest board with a bad Y output.
>
> Pressing reset (test switch on) and the test screen appears momentarily
> (a little distorted but recognisable) and then collapses into a blank
screen.
> Spot killer is on.
>
> Advancing to the checkerboard test screen (4th screen), Y direction is
> "scrunched" into about a 1" area of the screen. Spot killer on.
>
> Checking with a scope:
>
> The output of the X multiplier (C12) looks good, pin 14 (output) is same
as
> pin 9 (input) but downscaled.
>
> The output of Y 1495 (C13) looks bad, pin 14 (output) bears no
similarily to
> pin 9 (input). Also, the input is perhaps somewhat skewed, hard to tell
on
> the scope.
>
> I socketed C13 and replaced it (known good one), with no change.
>
> There is what appears to be a noise? waveform on pin 18 of F10 (Y AM6012

> DAC). There is no equivalent waveform on pin 18 of A10 (X DAC), rather
a
> straightline. On a good working board, no output on pin 18 for either
X
> or Y DACs.
>
> I socketed and replaced F10 (Y DAC) with no change.
>
> I don't understand the DAC/BIP circuit, the relationship between the IO
> (pin 18 - is this the analog output?) of the AM6012 and the BIP circuit.
>
> If anyone has some beginner level circuit descriptions and
troubleshooting
> advice, I'd appreciate hearing it.
>
> Thanks
>
> Tony
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Received on Wed Feb 12 13:13:01 2003