Patches and discussion for Ensoniq VFX family

On Sep 2, 2012, at 9:00 PM, Daeron <daeron_elf@...> wrote:

> Oh! thanks a lot for your support! somebody know the part number of the controller chip? i found this: Display driver integrated circuit chip, TL4810BN on syntaur!

Actually, the display board on the VFX-series of boards uses two different driver chips to drive the VFD (Vacuum Fluorescent Display). In that respect it is similar to the ESQ1 - whose display board schematic is here: http://memi.de/~buchty/ensoniq/schematics/esq1/esq1-display.jpg

As on the VFX / VFX--SD / SD-1, there are two different chips, both with similar function:

4 * TL4810A to drive the choice of segments; and
2 * TL5812 to drive the columns.

Basically, the VFD works by lighting up those segments that are addressed by the combination of the selected column (40 columns, one pin for each column => 40 pins) and the selected set of segments (2 rows of characters with 14 segments per character => 28 pins).

The driving chips are shift registers, into which data are written sequentially, and then presented in parallel. The TL4810A chips are 10-bit shift registers, and the TL5812 chips are 20-bit shift registers.

The two TL5812:s are arranged sequentially to comprise effectively a single, 40-bit shift register, their 40 outputs each connected to one of the 40 'column' pins on the VFD; the 4 TL4810A:s are separate, each connected to separate input pins from the 6500 processor, and each having 7 of its outputs connected to 7 of the 'segment' driving pins on the VFD.

In order to draw a complete screenful, I believe the display board does the following.

The display board iterates through each column on the board. It does this by shifting a single '1' into  the 40-bit shift register comprised of the 2 TL5812:s. At the beginning of displaying a screenful, we thus have a single '1' and 39 '0's present on the column-driving pins of the VFD, thus effectively selecting column 0.

At the same time, it shifts 4 sets of 7 bits, one into each of the TL4810A:s, thus specifying which 4*7 = 28 segments should be lit in the 0:th column of the display. 

This means that the display will light up precisely those selected segments in column 0.

Then a '0' is shifted into the 'column' shift register, advancing the '1' to select column 1; and a new set of 7 bits per register are shifted into the 4 TL4810A:s, to specify the set of segments lit in that column, and so on.

Troubleshooting-wise, this basically means that if you have symptoms where the left or right half of the display is messed up but the other (right / left) half is OK, it's likely a problem with one of the TL5812 chips. If you have problems with some of the segments in all characters in one row, that indicates an issue with one (or more) of the TL4810A chips.

Intriguingly enough, I've found both TL5812:s and TL4810:s  on eBay:

  http://www.ebay.co.uk/itm/120922031767

  http://www.ebay.co.uk/itm/110886748416

(the TL4810BN is an improved version of the TL4810A).

Best wishes,

// Christian Brunschen


> 
>  please sorry for my bad english is not my native language!
> Daeron...
> De: jammie <jammie.emma@blueyonder.co.uk>
> Para: Ensoniq-VFX-SD@yahoogroups.com 
> Enviado: Domingo, 2 de septiembre, 2012 14:52:01
> Asunto: Re: [Ensoniq-VFX-SD] Ensonix VFX-SD no work!
> 
> the fip controller chips are fualty
>  
> its a common problem on the asr10
>  
> and the esq1 sq80
>  
> so its no suprize that the vfx has the same fualt as the esq1 and sq80 vfx sd and the ts10 all use the same display
>  
> and you cant get the chips any more i know i have tried as i fix these all the time
>  
> we are working on an fpga design to replace but still in the designing and testing phase
> ----- Original Message -----
> From: STEPHEN PRATT
> To: Ensoniq-VFX-SD@yahoogroups.com
> Sent: Sunday, September 02, 2012 8:21 PM
> Subject: Re: [Ensoniq-VFX-SD] Ensonix VFX-SD no work!
> 
>  
> How old is the backup battery?
> 
> On Sep 2, 2012, at 2:58 PM, Daeron wrote:
> 
>>  
>> Hi! some body help me! my vfx-sd don't work any more, i change the power supply but nothing! i push the power on and just a little flash on the display!
>> like this: http://www.youtube.com/watch?v=dNBW3DluHj0&feature=plcp
>> 
> 
> 
> 
> 
> 
>