LagondaNet

[Steve]

HI, so had my crt wiring ( rat eaten) repaired and cleaned all of the boards etc to almost acceptable and once all reconnected ran the engine and no sign of life on any of the tubes ( i did have some life on centre and left screens previously before they gave up)
Time to get a professional in, they can tell me if Im wasting time and money.

I see 13501 has an LED conversion is that feasible?

cheers
Steve
13465

[Vincent]

All this depends on the deepness of your pockets…

I should say analogue dash would be more easy to install, knowing the fact that all analogue signals are transformed to digital signals on the dash.

Otherwise, David Marks has a solution, but it's fa
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[Steve]

Hmm I just don''t seem to be getting power to the high voltage boards I'll trace that back through the wiring broadsheet and see where that gets me.
If the CRT's actually work then it will be worth getting the signals to them working.
lf the CRT's themselves are stiffed then i guess I have a big decision to make......

cheers
Steve

[Steve]

Aha this might be the reason I have no power to the CRT's, the power supply unit is not connected!
Can anyone tell me how this is wired to the car?
On the power unit I have 2 feeds, 1 with a black and a white wire the other with black, orange and red wires.
On the car I have a twin black, a single black, a brown, a yellow and potentially a blue wire.
Below should open a couple of photo's

https://imgur.com/a/2ksHROT

cheers
Steve

[david]

Hi,

The white is 12V ignition supply.

The red is the 5V supply to the computer - this should go to the red wire of a twisted pair of red and black wires.

The orange is 12V to the CRT driver boards, via the single four way connector

DO NOT GET THE RED AND ORANGE WIRES THE WRONG WAY ROUND, VERY BAD THINGS WILL HAPPEN.

The blacks are all vehicle ground.

I would strongly advise that you check the output of the red and orange wires before connecting them.

All this pre-supposes that you have the later Audit Mk V computer with no external regulator and one video board with three outputs, rather than three video boards, each with one output.

I don't see how you could have had two screens working if this power supply was disconnected............

One has to wonder what is going on here, I would check everything very carefully before powering up the system.

Regards

David

[JohanB]

There is one more thing to check, there is (well at least on my car 456) a delay that switches on the power to the computer (only, not the screens). I found this out when I had put the computer back in the car and where it worked fine on the test bench nothing happening in the car. The moment you release the key post starting the engine it takes a few seconds and then the computer is powered. Normally one wouldn't notice as the CRTs take a bit of time to start displaying.
On the passenger side under the top dashboard panel there is a round capacitor like thing of a few cm long in the area where the stabiliser coils are, this is the timer and it steers a relay which then provides the feed to the computer. In my case the thing sometimes worked, most of the time not. Connecting the 2 wires on it forces the relay on and the computer gets power. I replaced with a $3 timer from Amazon. The thing itself makes sense, it basically avoids the computer being subjected to voltage swings directly after starting the engine.
My computer required cleaning of the contacts on the boards that slot into the backplane as well cleaning the backplane connectors. I replaced the electrolytic capacitors just to be sure.
The main change I did was taking the CRTs out with their high voltage boards and replacing them with 5" displays as used for car reverse cameras and available through Alibaba, Amazon. These are cheap and typically have both PAL and NTSC compatibility. The video outputs on the computer are NTSC. In my case 2 screens lit up, one didn't, this could have just been a bad HT contact on the tube, May be one day I will revert back to the CRTs but for now this was a simple solution to get a reliable and simple screen setup.
The new screens display in black and white, I'm guess that the video controllers can handle color so re-writing the video code should make it possible to get the right colors on the display. I went for a more basic solution, I used green advertising foil to stick over the screens and that way things are now green, small pieces or red and blue with some precision cutting sorted out the middle screen (which is also where I got the idea from...)
See the photos towards the end on https://goo.gl/photos/PgAUydkcbRs1y6u3A
hope the link works

[Steve]

Thanks David and Johan,

I have to confess, when pulling out all of the carphone wiring I disconnected the power supply and for some stupid reason didn't reconnect at all as soon as I had the phone stuff out of the way.

I have photographed everything I've done, well everything except when I removed the carphone!

For some reason i had to remove the metal bracket the power supply is mounted to to to trace the antenna wiring back to the boot.

cheers!
Steve

[david]

Hi again,

The CRT tubes are in fact very reliable and durable, we've only seen one failed unit so far and they are available from various sources.

As regards colour output, the AUDIT computer has 30 plus year old software and very little memory, it is not feasible to re write the software and in any case, the hardware is limited to black and white.

13501 had an analogue dash when we first saw it and at the time, it was agreed we (Robert!) would build from scratch a computer to handle the inputs from the car and output to three colour LCD screens a facsimile of the original display.

This was difficult, time consuming and expensive, these days, we have found that it is easier and less costly to repair the existing system if it is all basically there.

Finally, there is a "warmth" to the CRT displays that is missing from conventional LCD replacements, we were able to recreate that in 13501 but it took a lot of work.

David

[JohanB]

True, the CRT tubes are more warm than a modern display, I'm not saying that modern displays are better, I considered it a more convenient solution. My concern were the high voltage boards, these are now over 30 years old, were dusty, have for sure been hot given the KSA history of the car and I didn't feel like going down an exploration journey to see how long what would work or not. It has already taken long enough to get to this point.
I also thought that memory would be the main limitation when considering to use color directly from the video controllers.

[Steve]

HI David,

I have the "AUDIT" computer with 3 video boards, luckily it was spotlessly clean and all looked to be in. good working order.

Unfortunately that means the Red and Orange wires you mention above are not relevant to my system as I do not have a 4 way connector for the orange wire. (or any orange wire that jumps out as being the correct one.)

Whilst I seriously doubt anyone has a schematic of the wiring for the old Audit computer with the updated boards behind the CRT's has anyone got one apart at the moment who can point me in the right direction?

cheers
Steve

[david]

Hi,

If you have the computer with three individual video boards, this earlier version should have a heat sink on one of the outside faces and the power supply to it is simply a 12V supply via the normal connections - the regulator is internal to the computer.

The later versions that take a 5V input have one video board with three outputs on it, an external flying lead and no heat sink.

The flying lead is a twisted pair of back and red wires.

So, if you have the earlier computer and a later power supply, you should have three black wires that go to chassis ground - one of these may be the earth return for the video boards, an orange wire that is a 12V output for the video boards, this one wire goes to all three supply cables, that should be joined together and finally the red wire that is a 5v output.

If this is not used, it MUST be grounded via a 680 ohm resistor.

You must have the connector for the screen driver boards if you had two screens working before.

Send me some pictures if you want but you have to be sure about what you are connecting to what, 12V into a 5V computer will make for very bad things indeed....

David

[Steve]

Thanks David,

OK so I have everything ready to go, identified the correct wiring and have a couple of 680 ohm resistors in hand.

One hopefully last question, the resistor goes between the red 5v wire and earth correct? I know what a resistor does but still seems odd to earth a live wire?

cheers
Steve

[Lagondanet]

Steve. David is away for about a month I think. You might get a response to an email.

[Steve]

Thanks Roger, I don't want to bother David whilst hes away!

Just a random thought though, if the later poser unit with the earlier Audit unit only provides 12 volts in and 12 volts out and the computer itself is powered by normal 12 volt ex ignition, why not just have 12 v from ignition to the CRT amplifiers?

I really am out of my league here with the electrics, body, interior, paint and mechanicals fine but electrics ........

[Lagondanet]

I can't answer your question Steve but maybe someone else can?