Marconi TF 2023 Signal generator

[Wendymott]

Hi Peeps. I am fortunate to have two of these beasties.. however the first one I bought, for a reasonable sum, has a dimmer than usual display. It does eventually warm up but compared with the other, is still less usable. I surmise that the item was kept on 24/7/365..... thus wearing out the backlight or BL psu
I have a manual, but it seems to omit any useful info re the display.

I was wondering, has anyone better info on the fault, or point me to the Marconi group of enthusiasts. I googled "Marconi user group" but drew a blank.
It would be nice to have both usable. At present this one is just sat there.
Over to you

[Jon_G4MDC]

Maybe you are looking for this one Wendy?

https://groups.io/g/Marconi-Test-Instruments

[Wendymott]

Yes Jon.. Thanks

[Wendymott]

Hi peeps. Sorry if this is "old hat" but after my successful login as above yesterday, I had a reply from a EEV Blog member which covered the problems with my TF2023. Apparently there is a "retro fit" mod using a led. If any member has done this I would be most interested. The download I got, mentions it, but no detail.

[factory]

If the backlight is an EL type, they are still made, for some examples of what is available, this shop was linked on eevblog recently; https://www.backlight4you.com/EL-Pan...ml?language=en
There was a comment about not cutting them down to size, as they fail if they absorb moisture.

Or if it's a CCFL backlight, maybe there are replacement out there too.

David

[Wendymott]

Hi David. At the moment its all a bit "Vague" as I have not opened the TF 2023. It started as a comparison between my good one and the "not so good" one. I just put it out there to see if anyone else had experience with the problem... I am going to put things on hold for a bit as I am going on my hollybobs. When I get back I will be rareing to go "not" Mod please close for the time being.. Thanks

[Wendymott]

Hi Peeps. Back from my hollybobs, I have retro fitted the new Display obtained from CPC.
It is a SC15029 by Winstar. There is a little "faffing" to fit the display as it is slightly less wide and extension plates were made. Also the new display has a 10 X 10 IDE type connector, rather than an inline 20 pin connector.
The HV module was replaced by a home made pcb to supply 3.5V DC from a 5V source, with 2 X 39 R 's in parallel .
I only have one issue. On the data sheet pin 9 is Vee "Negative voltage". Now.. heres the problem... The 20 way ribbon has pin 9 blanked off. So I left wire 9 "hanging", as I dont know what to do with it. The display works ok, but the background is a bit brighter than it should be. With the Hitachi LCD displays, pin 3 is connected to a variable voltage set by a 10K pot, Should I be doing this with pin 9 ?. In the data sheed on page 5 it shows a similar arrangement but with the bottom end of the pot going to VEE .
Has any one a suggestion please
Other than that the 2023 is working fine, but before I re case it I need to know about wire 9.

[frsimen]

Hello Wendy,

The datasheet for a different Winstar LCD display shows that there is a 10-20k potentiometer connected between the negative supply output at pin 9 and the positive rail, with the slider going to the adjust pin. That seems to be similar to the arrangement that you have.

Paula

[Wendymott]

Hi peeps. The TF 2023 is now sorted. The solution is just to leave the pin 9 wire floating.. Pin 4 already generates the 7V LCD voltage.