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The eTim board looks great but I’m really disappointed he hasn’t included attenuation on the inputs and you’re expected to calculate this with horrible multi gang pots.
Hi

Attenuation cloud be done using soldering jumpers on the pcb or just use a 220ohm resistor for each video line, thats all. No need to use the pots.

Have a Nice day
 
I have an update.

It works! Sort of.

I rebuilt my mini DIN 8 connector, cleaned up my soldering and wiring and on the PVM it's a bit darker than I would probably like but it works correctly and all colours are present and correct.

On my Panasonic consumer CRT, no dice. No sync and colours are REALLY dim. Thinking I need to bypass the 75R resistors on the output but I am checking with someone who knows before I do that.

Thank you for your help @SVM!

Edit: found the problem, because most people are using these on PVM monitors without internal 75R termination the voltages from the board are already at a safe level.

On my PVM where I'm using BNC connectors with 75R termination inbuilt and my consumer CRT which also has termination inbuilt the 75R on the board means I'm ending up with half the voltage I need so I don't get sync and colours are really dim.

I connected all wires before the 75R resistors and I got nice bright colours like I was expecting. Still not getting sync, it's just slightly lower than I need it to be but I can work around that.

When I connected it through a CSY-2100 and ran it on component it works fine so I'm up and running!
 
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Yeah, these are realy good news! :thumbsup:

Maybe you could solve the last "sync issue" by playing around with different values for R1 and R8?
 
Quite possibly, I don't need much more voltage, it's locking on then rolling so it's really close.

It looks like I'm getting 0.7-0.8v and the TV is being picky about wanting it to be closer to 1V
 
Are the last group of 75ohm resistors pulldowns or in series?
 
I think this PCB is incorrect regarding all (RGBS) output voltages, in regards to resistor values. I also believe it assumes a 5Vpp signal from the MVS PCB which isn't actually the case.
 
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Ok. So please enlighten us with some concrete suggestions. ;)
 
I think this PCB is incorrect regarding all (RGBS) output voltages, in regards to resistor values. I also believe it assumes a 5Vpp signal from the MVS PCB which isn't actually the case.
Yeah, judging by the resistor values it assumes 5Vp-p on all signals. You could get away with incorrect values for colours, but the MVS' CSync amplitude is actually ~4Vp-p, so with a voltage divider consisting of 9K53 and 620R you end up with ~0.24Vp-p CSync - not enough. It would explain why it worked when xodaraP skipped the 75R output resistors (CSync ~0.5Vp-p).
 
Also explains why some people are experiencing a dim picture.

The circuit is nice being AC coupled but I'm not sure the biasing is correct and the resistor values definitely need to be altered.

Incidentally, I'm not a fan of vias on pads but that's just my preference.
 
I think this PCB is incorrect regarding all (RGBS) output voltages, in regards to resistor values. I also believe it assumes a 5Vpp signal from the MVS PCB which isn't actually the case.
Yeah, judging by the resistor values it assumes 5Vp-p on all signals. You could get away with incorrect values for colours, but the MVS' CSync amplitude is actually ~4Vp-p, so with a voltage divider consisting of 9K53 and 620R you end up with ~0.24Vp-p CSync - not enough. It would explain why it worked when xodaraP skipped the 75R output resistors (CSync ~0.5Vp-p).
It still doesn't sync on my CRT TV, it locks for half a second and scrolls again so it's close. @Frank_fjs is going to work out the values I should have and order some replacements for me.

It does work when I run out through a component converter.
 
@Frank_fjs is going to work out the values I should have and order some replacements for me.
That's cool!

As I've already mentioned before the pcb is based on theoretical calculations by borti4938 (he never had a MVS or AES in front of him and I don't own an oscilloscope). So if someone has an oscilloscope and can adjust the resistor values this would be realy nice and helpfull for further improvements. :thumbup:
 
It's perfect the way it is, provided you're running it through a PVM without terminated jacks.

The colours when I bypass the 75R output resistors are absolutely beautiful. I have 75R terminated BNC to RCA connectors on my PVM and a consumer CRT.

The sync is ever so slightly off. Couple of resistor changes (so I'm using it properly terminated) and sync will be happy and I'll use the correct pads and away I go.

Through the component converter it's fantastic.
 
Ok, another update:

I made some changes to the resistors on the inputs based on my voltages. Colours are now perfect without bypassing the 75R termination resistors and on my PVM it runs perfectly.

For reference based on a 4.7V colour and 4.3V sync input which is what I'm getting:

R1: 4.7k
R2/R3/R4: 6.8k

Gives me an output of 1.08v and 1.6v on RGB lines before voltage division resistors.

Sync is still an issue on my CRT and I'm not sure why. I haven't tried it on OSSC yet to see whether it works there. It may be a refresh rate issue but the Minigun runs Neo fine on the same TV so not sure what's causing that.
 
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I’m thinking I need a circuit incorporating the LM1881 as a sync cleaner for the CRT which won't hurt OSSC output either. I might see if something already exists.
 
I upgraded my AliExpress Consolized MV1c ... The pic was a bit dark but I adjusted brightness in OSSC.

I am in love with the Sharp SEXY PIXELs
Do you have the schematics for the CMVS CBox from aliexpress? Curious how you have it wired up.
 
Also explains why some people are experiencing a dim picture.

The circuit is nice being AC coupled but I'm not sure the biasing is correct and the resistor values definitely need to be altered.

Incidentally, I'm not a fan of vias on pads but that's just my preference.
@Frank_fjs - I was talking with SVM, and I'm planning to create an updated gerber file to add some design tweaks to better suit a CMVS kit I'm building (through holes to easily couple the board with a mini din 9 board I'm piecing together and bypass jumpers for the 75ohm end resistors if you are using cables with resistors already on the RGB lines). Any idea on what resistor values you'd recommend for the updated pcb?
 
I wrote some notes down ages ago, let me see if I can find them...

@xodaraP might have some info to share too as he experimented with different values and obtained a nice result in the end.
 
I made a note of the values I used above (completely forgot I did that too!) and it turned out pretty well. I only changed those resistors.

I still couldn't get it to sync properly on my TV but it works great on PVM and through OSSC or a component converter :)

I'd be really keen on one of your new PCBs, especially if it includes a sync cleaner circuit - I used a mini DIN 8 connector but 9 pin would also work well.
 
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