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Update on my 7854 diagnostics project


Holger Lübben
 

Hi

As promised an update about my 7854 diagnostics project:

I've finished all tests with my ROM card replacement. After that I've tweaked the layout a little bit and ordered a final sample.
These are pictures of the earlier prototypes:

ROM card:
http://methodyn.de/p/proto11.jpg

Keyboard-overlay card:
http://methodyn.de/p/proto12.jpg

Last week a good friend borrowed me his MicroLab. So at the moment I have a (nearly) complete 7854 digital diagnostics sytsem at home.
Pictures of the system can be found on Tekwiki:

http://w140.com/tekwiki/wiki/067-0911-00
http://w140.com/tekwiki/wiki/067-0961-00
http://w140.com/tekwiki/wiki/MicroLab_I

I've also uploaded the bin files.

Next step is to analyze and understand the system in detail.

Holger


Ke-Fong Lin
 

Hi Holger,

If that's not a secret, where did you have your keyboard overlay card manufactured?
There's multiple sources of PCB fabs that are very good quality, and cheap.
But I've trouble finding a suitable front panel manufacturer.
Thank you.

Best regards,


Holger Lübben
 

Hi!

The trick is: In this case the front panel is also a pcb ;-)

This board is 0.8mm thick, white soldermask and black silk screen.
Here is a closeup of one of my red & white ones:

http://w140.com/tekwiki/images/7/77/P7001_program_overlay_card.jpg

If you look closely you can see the copper borders under the silkscreen

There a two downsides:
1) You can't get inner holes with sharp corners - usually you have to deal with 3mm corners. Thats the reason why my 7854 keyboard overlay card has a big hole per keyboard row - compared to individual holes for each key on the original card
2) I've tried a local pcb manufacturer and one of those cheap chinese ones and both reuqire at least one pad on the pcb. Thats the reason for the two pads on my panels.

But beside from that: They are great and look even better in real world.

If you want to have professional front panels you can also use services like www.schaeffer-ag.de. That's one of the local german ones, but I think you'll find such a company in every country.

Holger


 

Hi Ke-Fong-Lin,

I think Holger's solution of having them done by a PCB house was quite clever and it is inexpensive as well.

There are a lot of franchise stores that make inexpensive signs. A simple Google search I just made for "low cost signs" found thousands of them.
Most of these places might be surprised if you asked them if they could do holes or holes for individual keys.
But it might be worth searching for this capability since it will probably come in handy sooner or later.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Holger Lübben
Sent: Saturday, May 23, 2020 8:07 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Update on my 7854 diagnostics project

Hi!

The trick is: In this case the front panel is also a pcb ;-)

This board is 0.8mm thick, white soldermask and black silk screen.
Here is a closeup of one of my red & white ones:

http://w140.com/tekwiki/images/7/77/P7001_program_overlay_card.jpg

If you look closely you can see the copper borders under the silkscreen

There a two downsides:
1) You can't get inner holes with sharp corners - usually you have to deal with 3mm corners. Thats the reason why my 7854 keyboard overlay card has a big hole per keyboard row - compared to individual holes for each key on the original card
2) I've tried a local pcb manufacturer and one of those cheap chinese ones and both reuqire at least one pad on the pcb. Thats the reason for the two pads on my panels.

But beside from that: They are great and look even better in real world.

If you want to have professional front panels you can also use services like www.schaeffer-ag.de. That's one of the local german ones, but I think you'll find such a company in every country.

Holger






--
Dennis Tillman W7pF
TekScopes Moderator


Ke-Fong Lin
 

Hi Holger and Dennis,

I'm already using PCBs as front panels for prototyping purposes:

https://drive.google.com/open?id=11nPji-pEWEQprJ6F2HMOWq0KOPtgqoQT

It's very cheap and convenient. I was rather looking for something not so "prototyping" and "internal" use.
Holger, it seems the minimum of one solder pad is needed for gerber drilling information.
Kicad is unable to generate correct gerber files if there's not at least one.

Shaeffer AG is well known but expensive. Another potential manufacturer is beta-layout.
I've never tried any of them.

Best regards,


Gregor Lasser
 

Hi Holger,

Great job, that all looks amazing and I am curious about a future report what the microlab diagnostic system can do!

Maybe even more interesting to those people (like me) owning a 7854 but not a Microlab: is there any use of the 067-0961-00 memory board without the Microlab?

Finally, I am curious about your source of the nice plastic tabs on your 7854 reproduction card, because the TEK originals seem to fail pretty often. Where did you get them from, and are they mechanically compatible to the TEK originals?

Liebe Grüße aus Boulder,
Gregor

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Holger Lübben
Sent: Saturday, May 23, 2020 6:15 AM
To: TekScopes@groups.io
Subject: [TekScopes] Update on my 7854 diagnostics project

Hi

As promised an update about my 7854 diagnostics project:

I've finished all tests with my ROM card replacement. After that I've tweaked the layout a little bit and ordered a final sample.
These are pictures of the earlier prototypes:

ROM card:
http://methodyn.de/p/proto11.jpg

Keyboard-overlay card:
http://methodyn.de/p/proto12.jpg

Last week a good friend borrowed me his MicroLab. So at the moment I have a (nearly) complete 7854 digital diagnostics sytsem at home.
Pictures of the system can be found on Tekwiki:

http://w140.com/tekwiki/wiki/067-0911-00
http://w140.com/tekwiki/wiki/067-0961-00
http://w140.com/tekwiki/wiki/MicroLab_I

I've also uploaded the bin files.

Next step is to analyze and understand the system in detail.

Holger


Holger Lübben
 

Hi Gregor!

All capabilities of the complete digital diagnostic system can bee seen in the manual on this page:
http://w140.com/tekwiki/wiki/067-0911-00.
The microlab only serves as an user interface - the real job is done by the 7854 itself with the help of the 067-0911-00 interface and the 067-0961-00 memory card.

The 067-0961-00 memory board can be used within the calibration process. A detailled description can be found in the service manual of the 7854.
In my manual (revision Jan '82) its section "GA - Display System, page 4-79". In later manuals it's in other chapters.
The software on the memory board is much faster than the alternative described in section "GB".
So at least the vector timing will be more precise.
The other features of using the memory board are described in the manual on the first link. It's the chapter "using the calibration firmware" on page 2-6.

Keystone electronic still produces various pcb card ejectors and other pcb-related parts:
https://www.keyelco.com/
The model number 8642 is mechanically compatible to the ejectors in the 7854. The only difference is the missing area for the stickers.

Greetings back from Nothern Germany
Holger


Gregor Lasser
 

Servus Holger,

Many thanks for the explanations and the source for the plastic tabs! I do remember the tedious procedure of typing the code on the waveform monitor to create the "window" display for the stored screen calibration when I performed a partial calibration of my 7854. So here the 067-0961-00 Diagnostic Memory Board is nice to have but not essential for a calibration.

The other features described in 2-6 of the diagnostic manual are more interesting, particularly the histogram and the true sampled display (without those interpolated points) would be interesting to try. Please let us know if you will be offering your combined ROM card for 7854 enthusiasts.

Liebe Grüße,
Gregor

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Holger Lübben
Sent: Thursday, June 11, 2020 5:35 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Update on my 7854 diagnostics project

Hi Gregor!

All capabilities of the complete digital diagnostic system can bee seen in the manual on this page:
http://w140.com/tekwiki/wiki/067-0911-00.
The microlab only serves as an user interface - the real job is done by the 7854 itself with the help of the 067-0911-00 interface and the 067-0961-00 memory card.

The 067-0961-00 memory board can be used within the calibration process. A detailled description can be found in the service manual of the 7854.
In my manual (revision Jan '82) its section "GA - Display System, page 4-79". In later manuals it's in other chapters.
The software on the memory board is much faster than the alternative described in section "GB".
So at least the vector timing will be more precise.
The other features of using the memory board are described in the manual on the first link. It's the chapter "using the calibration firmware" on page 2-6.

Keystone electronic still produces various pcb card ejectors and other pcb-related parts:
https://www.keyelco.com/
The model number 8642 is mechanically compatible to the ejectors in the 7854. The only difference is the missing area for the stickers.

Greetings back from Nothern Germany
Holger