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Vectrex not working

Cartridge has arrived. I will test it tomorrow but need to either see if I can reprogram the W27C512 or try to dig out my EPROMs, programmer and eraser.
 
Flash programmed and stuck in the working machine

Came up with a title (oddly seemed to say DER instead of VER) then cleared it and went no further. Haven't had time to really try it out yet though.

Faulty machine seems to be a faulty IC base on the VIA.
 
The screen should stay blank (I take over the machine and 'kill' the vector generation on purpose).

The DAC output voltage (to the analogue multiplexor input) should be varying with time, and the DAC bits should be changing state.

Dave
 
Ah, good.

Looks like it working then.
Will do some more testing on Wednesday.

Quite good this W27C512, much easier than fiddling about with erasers. Seems to work fine with the Vectrex. Are there replacement versions for all 27## EPROM sizes ?
 
I will next be able to test it on Wednesday, and will be able to test multiple versions if you have any.

And just realised that the lst file is there

So on the working machine, I can see that it writes VECTEST DER V0.0A before stating the test.

The DER made me thing something odd was happening.
 
Just that version at the moment. I just want to see if it initially works and I am not wadting my time!

After that, it is going to be a case of what we want to test. I have a few ideas...

Dave
 
I will need to box up the customers machine as soon as its fixed. Can continue with the other unit though.

It seems with the faulty one, that the VIA socket is somehow shorting out and pulling down in a way that isn't totally apparent.

But I can't find my RS green sucker. Its by far the best tool I have.

As to what to test, I imagine its RAM,VIA, DAC, current to voltage, sample and hold and Integrators. There seems to be adequate tests for screen alignment once its working.
 
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That's very similar to what I thought also.

We test one 8-bit port of the VIA with the DAC anyhow.

We should test the other port of the VIA with the mux and integrator control signals.

I am thinking about drawing a simple right-angled triangle on the screen.

That should test out moving one integrator at a time (with the other integrator static), and both integrators concurrently (for the hypoternuse).

I should be able to run a RAM and ROM checksum test. I just need to think about how to display the results. Possibly with a series of dots in a horizontal line on the screen?

 Dave
 
Ok, VIA socket replaced and the machine is now running reliably if a bit skewiff.

So test run

System displays the test and version on the screen before starting the test itself.

Pin 1 of IC 304 ramping from -2.4V upto +2.4V then steps back to -2.4V and repeats as expected.

Obviously with pin 6 high of the multiplexer, there are no outputs to the sample and hold circuits.
 
One pin though has fallen of my W27C512 :(
Need to order a new one

Cant run the calibration program because it doesn't recognise any button presses so I cant select the tests, so I suspect the sound IC is not reading (and I dont have the speaker plugged in). Button inputs are all pulling down ok.

Ho hum, new EEPROMS and sound chips ordered.
 
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I have tweaked the source code to now operate the MUX channels at specific DAC thresholds. This should allow you to test the MUX and S&H ICs.

Let me know when you are ready, and I will go through it with you (if you can't be bothered to read the source code comments).

If this works, we can then look to try and draw some vectors!

Dave
 

Attachments

Ok, hopefully next Wednesday, only hampered by the detached leg on the EEPROM.

However, when I click on the link, im downloading an empty ZIP file. Last time I just went to your workspace, but this just has the last version.
 
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