> On 20 Mar 2014, at 14:47, Joe Sleator <joe.sleator@gmail.com> wrote:
>
> Hi James,
>
> Well, it _might_ be as simple as a shorted winding in the primary of the transformer inside the VDU. Have you got a series III service manual?
> I'd also be verifying the AC signal pins at both ends, also checking the cable for a short-to-shield or metal plug body.
> I'd also check between the chassis of the VDU and both AC leads. Shouldn't be too hard to take that plug apart both ends. Even easier just to check it with an ohmeter or buzzer.
>
> The resistance between both AC leads into the VDU (without the cable plugged in) should be small but not zero, and should not ever appear to connect to the chassis, that's my first guess.
>
> If your cable's good and you've got another source of ~16VAC, roughly, I'd also try that instead, directly to the PCB, after you check the fairlight supply/video cable. A variac+fuse would do, I've got one, but I suspect I'm a bit far away to loan it to you.
>
> I don't clearly remember whether there's an SIII vdu schematic in the service manual or not, but I can have a look soon. If you have a copy of the SIII service manual (wasn't it downloadable?) you can check yourself.
>
> Regarding the internal cabling for the composite video, I'd have to pull apart my SIII vdu and check, unless the position is shown inside the schematic. I'd have thought it fairly obvious on the VDU pcb, perhaps even clearly labelled.
>
> The SIII monochrome greenscreen VDU is not particularly special. I don't think there are any LSI chips in it at all, it'd all be transistors, transformers, diodes, and so forth.
> Simpler even than a MAC classic vdu board.
>
> It is VERY interesting that the CMI 16VAC fuse blows without blowing the VDU fuses, though. Makes me think there's actually a short in the supply cable! Verify that.
>
> It HAS had its frequencies tweaked to be able to cope with the higher horizontal frequency, but analog monochrome monitors can sometimes do that. I've got an old apple II monochrome monitor that'll take the CMI monochrome video signals. I seem to recall it used a switched inductor in the horizontal signal path to get a higher horizontal rate.
>
> Please check your supply cable first. Let me know.
>
> Cheers,
> Joe
>
>
>
>> On Fri, Mar 21, 2014 at 12:36 AM, James Thomson <jamesthomson9@googlemail.com> wrote:
>>
>> Hi Joe,
>>
>> Thanks to Peter Wielk and yourself for helping out. Yes silly me, I thought power was supplied to the vdu from the Q-219 card !
>> Anyway I have plugged the 10 way black female connector into the top slot of the Q-219 card. I have double checked the vdu cable to the mainframe and it's ok.
>> I have the bottom plate removed from the Multitech vdu . When I connect the internal two red wire connector to the main board inside the vdu and then power up the CMI the fuse in position 9 beside the PSU underneath the mainframe blows.
>> Something inside the vdu is causing gone VDU fuse ( position 9 ) to blow. The red VDU + 16 V light goes out on the rear of the mainframe as soon as the fuse blows. I have checked both fuses inside the vdu and they seem fine. I am missing the actual internal video signal cable which connects between pin 4 of the belling lee connector inside the base of the vdu to the motherboard inside the vdu case. Do you know what this connecting cable looks like and where does it connect to on the main board of the vdu?
>> Regarding the 10 fuse positions beneath the mainframe. What are the values of each ? It seems position 10 is empty. Thanks.
>>
>> James Thomson
>>
>>> On 20 Mar 2014, at 11:58, Joe Sleator <joe.sleator@gmail.com> wrote:
>>>
>>>
>>> Hi James,
>>>
>>> On my Q219s, the lower 10 way (S0) are the LP signals, and the upper (S1) is the video.
>>> This is confirmed by the IIx service manual, both in the schematic, and in the theory of operation pages for Q219 page 41.
>>>
>>> S0-pin4 is 5V for the lightpen, presumably, but the cable doesn't seem to carry it.
>>> S0-pin2 is LPHIT-bar
>>> S0-pin5 is LPTOUCH-bar
>>> S0-pin7 and S1-pin7 are composite video out.
>>> S1-pin8 is earth for the video.
>>> S0-pins 1,3,6,8,9,10 are earth
>>>
>>> On the series III the 10 way carries only video to the back panel, thence out to the vdu.
>>>
>>> But if you're just looking for video, looks like either connector would work as long as composite and earth are the only connections.
>>>
>>> But to suss out the VDU, you can simply inject normal composite video into the relevant lines plus earth. You don't strictly need a CMI, but you'll need the AC power for the Series III vdu.
>>>
>>> Get hold of the service manual for the series III and verify the power connections on the cannon (amphenol?) connector that goes to the vdu. The PSU lights on the SIII have a label for VDU power to help you.
>>>
>>> Lemme know how you go...
>>>
>>> Cheers,
>>> Joe
>>>
>>>
>>>
>>>> On Thu, Mar 20, 2014 at 12:25 AM, James Thomson <jamesthomson9@googlemail.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> I am trying to get my original CMI series 3 vdu display unit to work. There are two 10 pin male amphenol connectors on the front of the Q-219 mono graphics card. Which one do I plug the 10 pin female connector into , the top or the bottom one on the card ? This 10 pin female then takes power from the Q-219 card to the rear of the CMI which then supplies 16V AC power to the vdu. Thanks .
>>>>
>>>> James Thomson
>
>