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Tech Chat Geek Out On Some Vintage PCB, Silicon & VFD

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crustytv
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Decommissioning an ex M.O.D avionics test rack to facilitate the build of my V2.0 signals project, I needed to remove the rather large centre module. I have to say whilst in the process of decommissioning I came to appreciate absolute attention to detail invested. It soon became obvious the entire device had been constructed "in-house". The aluminium rack housing bearing cross score marks where the engineer had marked out cuts, or drill holes etc.

The PCB, were equally a work of art, it was a shame to depopulate them but needs must. When I got to the largest module, the centrepiece, this revealed some really nice period parts, a VFD and an M27C512-15F1 EPROM. Thankfully I won't need to depopulate this module as the LCD monitor will be occupying the space. Who knows, maybe the VFD and EPROM may be of some use in the future.

Thought some of you might appreciate some pics.

pcb01
pcb02
pcb03
pcb04
pcb05
pcb06
pcb07
pcb08
pcb09
pcb10
pcb11

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Posted : 28/09/2023 7:22 am
WayneD, Alex728, turretslug and 1 people reacted
Lloyd
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Could be interesting to inject some power into it and see what, if anything, comes up on the display!

Regards,

 Lloyd 

 
Posted : 28/09/2023 9:27 am
turretslug
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That is a splendid example of a VFD, hopefully it can be driven someway/somehow. I love VFDs, for their clarity, brightness and not least as one of the last outposts of thermionics. Never really liked LCDs, excusable as a minimal-power technology but otherwise unappealing- while there were inumerable LCD and plenty of LED iterations of the popular PIC frequency counter modules available for a song from China, I was pleased to find that there were just a few examples of a VFD version around. A bit more expensive, a bit more power-hungry but much nicer.

 
Posted : 29/09/2023 9:07 pm
crustytv
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Posted by: @lloyd

Could be interesting to inject some power into it and see what, if anything, comes up on the display!

Did just that this morning, 9V, and it's alive!

At first I just powered the VFD board, that just had a version code.

20230930 110557

I then connected it to the main module, that holds the EPROM, hoping it might load in the stored code, it did.

It draws around 260mA and periodically rises to 275mA, which seems to coincide with a display refresh. There are two blocks on the 3rd line, the second (cursor?) of these pulses for five seconds. At which point the cursor traverses the entire display 8 times (screen rewrite ?) ending back where it started, t repeat the process. I think the contents of the display is an address.

20230930 104346

There's a little flashing led on the board with the EPROM. Little else I can do, I suspect the rest of the main board required powering. The main board has a 12V linear voltage regulator L7812CV, I suppose I could give that some volts, which should power all the other main board related silicon.

20230930 111333

Nonetheless, very intriguing.

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Posted : 30/09/2023 10:04 am
Lloyd reacted
Cathovisor
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@crustytv Altenstadt is a area some 60km south-west of Munich - the address in the display is Südliche Römerstraße 12-16, 86972 Altenstadt and the company - Lechmotoren GmbH - is seemingly still in business as part of a company called Vincorion https://www.vincorion.com/en/

Thirty-odd years ago when I was buying components from the bright yellow STC (later ES, for Electronic Services) catalogue for the FM-AM converters Dave Grant and I were building - and Roederstein axial capacitors for radio repairs - the catalogue had several pages devoted to various VFDs and also another oddity I recall from petrol pumps, 7-segment filament displays.

 
Posted : 30/09/2023 11:46 am
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crustytv
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This time power fed in via the 12V regulator, VFD display is now powered via the main PCB. It loads as before, but now I have the bank of LED along the front flashing, no change in the VFD display info. I suspect it probably needs all the other modules in circuit and the D.U.T. connected. That's not going to happen because A) the other modules have been depopulated and B) I haven't a clue what device it would test, and even if I did, I seriously doubt I'd have one.

Here endeth the interesting diversion.

20230930 134623

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Posted : 30/09/2023 12:55 pm
Lloyd reacted
jjl
 jjl
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The boards were probably made around 2003 given the 0125 and 0248 date codes on the EPROM and UDN2543B power driver devices. It would be very unusual to see many if any through hole components or an EPROM in commercially made equipment from that time.

 

John

 
Posted : 30/09/2023 5:46 pm
crustytv
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Hmmm, just a quick & dirty test, but maybe there is a simple use for it after all, at least it won't sit in a junk box for decades 😎 

20231001 164913

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Posted : 01/10/2023 3:29 pm
Lloyd
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I was wondering if it could be re-programmed with something interesting!

 
Posted : 01/10/2023 4:18 pm
hamid_1
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Edit - I see you've already worked out how to change the message on the screen, by editing the EPROM contents. You could select a different message using a larger capacity EPROM programmed in two banks, then switching the address line to change to the high or low bank. I did this many years ago to make a 2-in-1 Vectrex game cartridge.

 
Posted : 01/10/2023 5:49 pm
crustytv
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@hamid_1

Respectfully, I think you'll find that's what I've already done two posts back.

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Posted : 01/10/2023 5:53 pm
hamid_1
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Yes, sorry, I've just seen the latest picture and edited the reply.

 
Posted : 01/10/2023 5:58 pm
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crustytv
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Decided what the VFD shall display, just simply what services the unit provides. I just have to figure how and where I mount this. Unfortunately, it cannot reside where it once did, as I've modified the plate to house the LCD monitor. Also need to figure out how I supply it with the 9V to power it.

20231002 072031

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Posted : 02/10/2023 6:42 am
crustytv
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Power resolved, and I've a rather neat solution to the placement, which involves another modification exercise to the setup. Hopefully all will be revealed in a few days time over in the Version 2.0 signals thread.

The photo below shows the module running not from the bench PSU, but its own 12V supply.

20231002 115844
20231002 120007

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Posted : 02/10/2023 11:06 am
sideband, Lloyd and WayneD reacted
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