dsa511 dsa524 Storage Scope woes

[bloke]

Hi there, noticed some discussion about this beastie on the group and
wondered if anyone had come across all of the relays clicking and
nothing else. It has been on the shelf for years and just when I need
to use it, it does this.

There is a grotty service manual floating about, but a good quality
scan of the digital schematics would be really helpful.

Anyway, any help would be gratefully accepted.

[N_Cook]

bloke <aston@photo-genic.net> wrote in message
news:57f2ce76-827f-40a9-a2ba-4f17fdb41cc5@9g2000yqp.googlegroups.com...


What a coincidence, this morning I was just about to put my one back
together to get back to exploring IR remote control hacking/cracking.

Persist with that low res schematic , it is useful.
But perhaps to save you going down a false route like me, I did not realise
the large UVC3120 was the main ADC not the ZNA449 which is probably just for
overlaying ch 1/ch2 levels of Y control.
In the process I managed to make matters worse and get that cyclic relay
business.
I removed the main processor chip VLC56C22 cleaned its pins and reinserted
and that problem disappeared. I suspect the original problem of no input
displayed , just the legends and levels was also due to surface corrossion
as that has gone , along the way
Mine is now working and I took a few scope pics of critical waveforms but
they won't be on the www for a week or more as I'm overloaded with work
If you work on the unit, [Only registered and activated users can see links. ] with polyester or paxoling the lower board
to middle board in one [Only registered and activated users can see links. ] and the front panel third in line beyond that.
But most important a 3mm threaded stud or similar to brace the lower board
to the vertical back pannel with the weight of the transformer

Do you know of a user manual without a hefty fee, as I will need to explore
the delay/trigger options and recall or pc/RS423 options.

[N_Cook]

the datasheet for the ADC+DAC uvc3130 which is out there, is for the pins
used in this unit, the same as the uvc3120 same pinning

[bloke]

On Apr 22, 8:24*am, "N_Cook" <dive...@tcp.co.uk> wrote:

I think I might have the manual somewhere, I can pop it up online when
I find it, do you have a dump of the eprom as I'm beginning to suspect
the data on mine is looking corrupt. (after all it is over 20 years
old, it's done quite well). Refitting the main processor didn't stop
the relays on mine clicking, sad to say. The battery had corroded but
the board cleaned up nicely and isn't conductive, as far as I can see,
it's infinate ohms everywhere, so that's a bit of luck. Anyway,
backung up the eprom's firmware might be a good idea anyway as they
don't last forever and tti.co.uk dont have a backup, I asked them, and
they said nope.

[N_Cook]

bloke <aston@photo-genic.net> wrote in message
news:44dee50a-f554-412e-9e91-685e70f49e18@w7g2000vbg.googlegroups.com...
On Apr 22, 8:24 am, "N_Cook" <dive...@tcp.co.uk> wrote:
realise
for
that.
explore

I think I might have the manual somewhere, I can pop it up online when
I find it, do you have a dump of the eprom as I'm beginning to suspect
the data on mine is looking corrupt. (after all it is over 20 years
old, it's done quite well). Refitting the main processor didn't stop
the relays on mine clicking, sad to say. The battery had corroded but
the board cleaned up nicely and isn't conductive, as far as I can see,
it's infinate ohms everywhere, so that's a bit of luck. Anyway,
backung up the eprom's firmware might be a good idea anyway as they
don't last forever and tti.co.uk dont have a backup, I asked them, and
they said nope.

++++

Maybe replace the uP socket , my one had some definite green corrossion on a
couple of the socket pins, but as I say lightly abraiding the pins
immediately solved the continuous relay clicking performance.
I've taken the opportunity to remove the nicad and wire through a vent hole
to a couple of cells mounted on the rear (requires a wire link for the 2x
positive pins)
Reading / dumping eproms is not something I've ever done , under the ethic
that if it aint broke, don't poke .
How does partially corrupt eprom data show itself?

[bloke]

On Apr 22, 11:32*am, "N_Cook" <dive...@tcp.co.uk> wrote:

Righto, found the manual, have uploaded it here [Only registered and activated users can see links. ]
you'll see a popup and have to enter a captcha thingie but it's a safe
site. The eprom when read gives different data each time you read it,
and the data segments have random bits missing in words etc. If you've
got a working eprom they are usually good for about ten years, but I
have arcade equipment over 20 years still going strong, and also some
of only five that has gone bad, so it's a bit of a coin toss wether it
will go bad now, a week from now or five years. It's just one of those
things. Think of it as a floppy disk, it's about as stable as one of
those.

Anyway, hope the manual is of help, all the best...

[N_Cook]

This is the recent repair brief on the Thurlby DSA524, serial number 28046*
[Only registered and activated users can see links. ]
shows the test-bench layout with 4mm threaded stud [Only registered and activated users can see links. ] to the right
and the 2x screened signal leads are long enough for this layout
remove the plotter board
join the earth tags together
remove the BNC sockets from the rear so the midle pcb can lay next the
bottom board
With no power to the unit, the input relays are grounded at the relay
For monitoring the input amp/attenuator sections use the 100R resistors at
the top
of each section
Yellow lead is the trigger BNC one
pics , before I grabbed a tripod
[Only registered and activated users can see links. ]
showing LEDs as set for the test point scope traces
[Only registered and activated users can see links. ]
The variation at ZN449 p5 / 430R with changing ch1 and ch2 offset is not
coming via
the outputs of ch1 or ch2 preamp sections
Error ? in the schematic D8 1N4148 is in series with the ADC analogue input
not to analogue ground
..1V rms 400hz at input ch1, .13V pk-pk at ADC screened wire
some UVC3120 dc
all ADC digital outputs 3.4V dc
p20 n/c
p22 1.98V
p25 1.95
reset attenuator to 100mV and p21 UVC .4V pk-pk
change attenuator to 10mV and p27 has signal
M5165 varies with input
74AC374 o.ps are ok to 6264
p22 (06) of HM6264 from 74HC14 that feeds Y & G of 74HC244

Cut the trace to bridged p1 & p19 of the 244 and took low
p2 of the UVC had a semblence of sine wave input
244 gating signal is mainly H with trace remade
[Only registered and activated users can see links. ]
Trigger out 5V pk-pk
7 negative going pulses over 7mS then 5mS H
scope 2V / cm , 20uS /cm using the DSA ext trigger for triggering scope
in RUN and HOLD mode

In working order and normal view on ext triggered scope
(www site for how to take descent scope pics anywhere ? )
[Only registered and activated users can see links. ]
signal going to scope with internal trigger
[Only registered and activated users can see links. ]
or maybe the DAC o/p of the UVC , (mangled notes)

Started getting cyclic relay clicking and no normal function
74HC4075 , one of the 5 I had socketed as around the nicad, replaced with
CD4075BE as maybe dodgey connection there, still there , although all now
working again
Removed the VL65C22 , lightly abraided pins and reinserted
and relay clicking stopped
4KHz , .1V rms input ch1 , 50mV attenuator, AC 100uS TB
scope 50uS and 200mV / cm
p15 of Con1 ribbon between boards in HOLD and RUN mode
[Only registered and activated users can see links. ]
con1 dc in RUN or HOLD mode
1,3 ....
3.9V, 5,5,5,0,0,3.1,variable
2,4, ....
5,5,0,0,0,-5,7V

[N_Cook]

I had clipping to sine waves ch1 and ch2 , must have introduced an offset
somehow, AUTOCAL gnd+ac/dc keys cured that
Much better than my scope proper DSO for displaying IR remote codes