Modified CGA to VGA Scaler to accept clean sync RGB SCART

[dosucol1]

Why not just try an EL1883? It has hsync out, works at 3.3-5V and can replace the LM1881 without redesigning the PCB layout.

The 1883 data sheet mentions; composite sync out ,vertical sync out ,but just states horizontal out ,no mention of the word sync .so is this an error or ?

[bencao74]

I guess later (after it's completely tested /refined etc and on sale to the public)maybe we'll see a case of some sorts,like with the SLG3000 ?

Sure, I`ve not decided on a three layer acryl case or a two layer acryl case

hmmm, as talking of a enclosure. I need a kind of logo ...

I`ll check the proposed ICs for pin compability, availability and price.

[Almighty]

thanks a lot for all the kind and very motivating PMs in the last time for the sync strike project )

Project status is that the minimal goal is achivied:

RGB Scart -> Sync Strike -> GBS something Scaler -> SLG3000 -> LCD with scanlines

per Plug and Play

I`ve finished assembling 3 test units and now I`m going to order some parts for the first batch.

It would be fine for me to check the interest on SYNC Strike, so the pre-order is opened.

Just mail me (http://www.arcadeforge.de/?page_id=838) or send me a PM with

- Email
- Nick (if you have one)
- how many
- adress

I put you on my pre-order list for Sync Strike (first come first serve).

Price information will be posted as soon as possible. I`ve to search for some cheaper components. Bad example: the switch for selecting between hsync and csync costs currently 2.20€ that is not necessary. Ordering more parts will result again in a cheaper price.

Hello,

Send you a e-mail

[lettuce]

Where can i get a LM1881 IC from in the UK,i have looked on the maplin website but could find any!!. Managed to get all the other parts from maplin that Fagin listed just not the LM1881. Can someone help!?

[hellbelly]

try www.bitsbox.co.uk

[lettuce]

try http://www.bitsbox.co.uk

Cheers, ive found a LM1881N, i take it thats ok to use??

Also would it ever be possible to also wire up a HDMI socket to pair up with the Scart socket, so we can use the hdmi cables for xbox 360 and ps3 for example??

[Fudoh]

Also would it ever be possible to also wire up a HDMI socket to pair up with the Scart socket, so we can use the hdmi cables for xbox 360 and ps3 for example??

lol, sorry, no.

[bencao74]

I was in touch with some japanese modders via pm. Is there a need / interest for a jap scart version?

[bencao74]

Sync Separator eval:

EL1883, perfect, but only in surface mount. LM1881 was in THT. This is a absolute showstopper for my PCB
EL1881 does the same job as LM1881, but is not available anymore.
LMH 1980, 1981 : no pin compability, http://www.national.com/ds/LM/LMH1980.pdf

the EL1883 would have been great, but this IC can only be used with a soic adapter. Nevertheless, I`ll try first with LM1881 and the 740hc00 for the first units. As told before LM1881 does a fine job (prooved by the previous mentioned cga2vga scaler).

Later on it's easy to swap to EL1883 and the 7400 can then removed from the design.

[hellbelly]

Why not just try an EL1883? It has hsync out, works at 3.3-5V and can replace the LM1881 without redesigning the PCB layout.

I was doing some reading about the 1883, and it looks like you may have to add an extra resistor and capacitor to the comp video input, compaired to the single capacitor on the 1881. Have you tried the 1883 and are able to confirm if that is needed?

ta
Pete

[MKL]

Why not just try an EL1883? It has hsync out, works at 3.3-5V and can replace the LM1881 without redesigning the PCB layout.

I was doing some reading about the 1883, and it looks like you may have to add an extra resistor and capacitor to the comp video input, compaired to the single capacitor on the 1881.

The low pass filter is optional to reduce noise on the input signal so it doesn't propagate to the outputs. It is mentioned in the LM1881 datasheet as well, no difference with EL1883 in this respect.

[hellbelly]

Lovely, thanks for the clarification

[lettuce]

Ok i have tried to do the RGB mod to the scaler today, but when i select RGBHD output on the scaler i dont get a display from my PS2 connected up to the RGB scart, i get the on screen menu from the scaler so i know thats working. I have following Fagin's steps:

Pin 1 on the IC is HSYNC.
Both IC grounds can be connected to the composite ground on the SCART plug (pin 17).
Composite Input is SCART pin 20.
The CGA to VGA scaler has a RGBHV header and loom provided.
Wire the RGB of the header loom to RGB SCART (pins 15,11 & 7).
Wire the HSYNC of the header (grey) to pin 1 on the IC.
Wire the VSYNC of the header (yellow) to pin 3 on the IC.
Wire the GROUND of the header (black) to SCART pin 17.
Wire COMPOSITE SYNC from SCART (pin 20) to the capacitor in-line with pin 2 on the IC.
Wire IC Pin 8 (power) to the positive on the CGA to VGA scaler.
Wire the phono audio breakout to SCART pin 2,4 & 6 (Right, Ground and Left).

Now i have noticed that there is no info on pin 6 of the IC, am i right in thinking that both the capictor and resistor should be attached the this pin 6 of the IC, and ground from pin 4 (dasiy chained) which then goes to pin 17 on the scart. As i have the resistor soldered on the strip of the pcb that is connected to pin 6 of the IC and then on the next strip above soldered the resistor (which is in line with pin 7 of the IC but thats not soldered as no need for it) and then soldered the 2 together across the 2 strips with a single blob of solder the pic below helps show this......



Now does it matter which way around the capacitor and resistor are solder?, also am running the scaler on a 9volt PSU as could get the scaler to work on my 5volt PSU (no light on the scaler)

And some more pics to show how i have it wired up...





Does anything look wrong to anyone?? How can i trouble shoot this??

[fagin]

**Edit I need to check before stating what I have just edited out**

[hellbelly]

where you've soldered the capacitors and resistor on the lm1881 board, have you broken the tracks?

Pete

[fagin]

Input on scaler should be RGBs not RGBHV.

As Hellbelly has said as well.... the tracks are not broken by the looks of it.

[lettuce]

Ahhh, nah I didn't cut the trace for the resistor and capacitors, just to confirm I need to cut the trace between the legs for all capacitors and resistors on the board or just the capacitor and resistor connected to pin 6 on the IC?

[fagin]

All else the circuit will be about as much use as tits on fish!

[bencao74]

e as tits on fish!

you just made my morning

[ZOM]

All else the circuit will be about as much use as tits on fish!

[MKL]

Pin 1 on the IC is HSYNC.

No, it's composite sync. The LM1881 doesn't output hsync. If you input csync into pin 2 you still get csync from pin 1.

[lettuce]

All else the circuit will be about as much use as tits on fish!

I dunno................

[lettuce]

Ok have removed the traces from between the legs of all the capacitors and resistor and i still dont get a signal on the RGBS input


EDIT: Ok i have test all solder joints from one end of the circuit to the other end with my multi-meter (MM). And only one error i think im getting is the capacitor joints, regarding the pic below, if i test point A to A i get a reading on the MM, if i test points B to B i get a reading on the MM, but if i test points C to C i dont get any reading what so ever, should it be getting a reading from point C to C or is the capacitor at fault?

[dosucol1]

B-B,that is your .1uF cap on the csync input(LM1881 pin 2)It needs the linking copper trace cut between B-B ,otherwise Composite video is just bypassing the capacitor and going straight to the lm1818's input pin(pin2 )and there's no need for the VSYNC wire to be connected .The rgbs input/header you're using just needs the RGB H/Sync and Vcc/ground wires !

Sorry, looking at your solder points ,they are correct !B-B and so is the mm reading at all the other points !

[KBZ]

I still don't get it. Why would you need separate H and V sync when using this scaler. Mine works fine with C-sync and a sync cleaner from Jrok. What's the difference?

[lettuce]

B-B,that is your .1uF cap on the csync input(LM1881 pin 2)It needs the linking copper trace cut between B-B ,otherwise Composite video is just bypassing the capacitor and going straight to the lm1818's input pin(pin2 )and there's no need for the VSYNC wire to be connected .The rgbs input/header you're using just needs the RGB H/Sync and Vcc/ground wires !

Sorry, looking at your solder points ,they are correct !B-B and so is the mm reading at all the other points !

Yeah i get a reading from points a-a and b-b but when i test points c-c i get nothing!! Strange thing is if i test the legs of the capacitor (.1uf cap) and the legs of the reisistor (that are both connected to pin 6 on the IC) i get a reading!, i decided to unsolder them as i thought they might be faulty when they are removed i tested the legs of the cap and then the resistor i didnt get a reading at all where as before when they were soldered on to the PCB i did!! I then soldered the same resistor back onto the board and decided to test the legs again and guess what..............i got a reading from the legs!!!!!

Why when the resistor is out of the board i dont get a reading between the legs but as soon as i have place the resistor back in the board i started getting a reading between the legs??

[Shou]

I was in touch with some japanese modders via pm. Is there a need / interest for a jap scart version?

Yes!

[bencao74]

Hey,

I`ve sorted out some facts for the LM1881 and EL1883 discussion. With my current layout both have some pro's and contra.

LM 1881 deals with 5V- 12V input voltage. So PSU via Scart Pin 8 is safe in every setup. Dreamcast is known to be candidate who puts out 12V on scart pin8. LM1881 can handle this.

EL1883 can handle low power 3.3V - 5V. So it can't be powered with scart pin 8. Other scart pins delivers at max. up to 1V if I`m not mistaken.

This results in two options:

- Option 1 : Only LM1881 can handle safely power supply via scart. If not enough voltage via scart is delivered, then the external PSU can be used. With this option no real hsync can be provided. The added 7400 makes no sense here, coz it eats at maximum 6V.

- Option 2 : EL1883 can only be used with regulated external PSU. Hence a scaler is used in combination it can be taken from the scaler psu. Anyway, it`s more complicated to use, but real hsync is supported.


I tend to option 1, because it`s more simple to use and benefits from the automatic PSU via scart.

Option 2 needs a external PSU, but supports HSYNC. Nevertheless I can offer both options. I`ll add a option tag for my shop, the default is above presented option 1 with the LM1881

[Fudoh]

Who actually needs pure H-Sync ? 15khz RGB is generally output with composite sync (both on home systems and on the Jamma standard) while only 31khz RGB is usually output with seperate H and V-Sync signals....

[viletim]

bencao74,

Several game conoles that which had official SCART leads available do apply 12V DC to pin 8 of the SCART lead. Some examples are Super Nintendo (PAL), Sega Master System (French), Sega Saturn (PAL), MS Xbox, and possibly others. The Super Nintendo has current limiting on the line, if more than 2 mA is drawn the voltage will drop significantly. The load on SCART pin 8 is specified >= 10k ohms.

If you draw significant current from this signal line, you should expect regulated 5V, or regulated 12V, or unregulated and current limited 12V (ie. anything between 0 and 12V). What I'm getting at is that anything could be connected to this pin - you can use it as a power source - due care is required. Filtering and regulation are essential. Also note that an LM1881 powered by 12V will deliver sync pulses at a 12V amplitude.