dsa511 dsa524 Storage Scope woes

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, brace with polyester or paxoling the lower board to middle board in one plane 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.

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

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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.

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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.

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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?

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Righto, found the manual, have uploaded it here

es/62lozykzz 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...

This is the recent repair brief on the Thurlby DSA524, serial number 28046*

shows the test-bench layout with 4mm threaded stud brace 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 showing LEDs as set for the test point scope traces 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 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 ? )

signal going to scope with internal trigger 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 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

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

I know this is an old thread but it was all I could find. I was given one o f these DSA524s.

When I got it, I found that the battery was corroded and leaking. I do not know when that happened. I removed it and cleaned the board, but the DSA do es not work. I set everything as the manual said but all I get is a small s quare wave on my CRO which seems to vary in frequency. There is no text or anything sensible.

Sometimes when I turn it on it makes repeated beeping noises as well along with relay clicking. When this happens there is sometimes other garbage on the CRO.

The ICs were all re-seated as I took them out when I washed the corrosion f rom the PCB.

I dumped the EPROM and you can find a copy here: http://starwatcher-circuit s.net23.net/DSA524/ I don't know if it's 100% correct but I took several du mps and they were all the same. Would be nice to compare it to someone else 's from a working DSA524 though.

Does anyone have a suggestion what might be wrong? Can it work without the battery, for testing? Or is the battery required fo r correct operation?

Thurlby? my exploration of similar fault