BKM 68x clone noise

The place for all discussion on gaming hardware
Post Reply
atohmdiy
Posts: 57
Joined: Wed May 06, 2020 9:48 pm

BKM 68x clone noise

Post by atohmdiy »

Hello,
I own a bvm a14 and a20, so i waited for the bkm 68x clone. When i receive the two cards i was disappoint. These are working, but there is noise in the image. When i receive them it was very obvious, a lot of horizontal tingling, moiré like pattern, and some input (mister io board vga) have an annoying stairs like effect that.
Since then i am trying to reduce this problem, it's now at an acceptable level but in some games it's could be seen and it's very annoying.
I own two others bvm, a 20f1e and a 2010. If i compare side by side with the same signal, the bvm with sony cards have no problem at all. And i tried everything, change the dac, cable etc.
I want to know if i am alone in that case, there is surely some owner of A series bvm with the bkm clone.
daty2k1
Posts: 69
Joined: Mon Mar 09, 2020 9:31 am

Re: BKM 68x clone noise

Post by daty2k1 »

Nothing of the sort on my side with A20. Picture is basically perfect.
atohmdiy
Posts: 57
Joined: Wed May 06, 2020 9:48 pm

Re: BKM 68x clone noise

Post by atohmdiy »

There is a few weird things. When i connect my mister with io board, i find that turning the SOG switch off is like a noise generator. I made a video to show it (mister io vga direct to BVM), it's hard to capture and it's a lot more annoying irl. But you see the horizontal tingling, and it get better when i switch the sog switch to on at the middle of the video :

https://youtu.be/qooIPTWwSoA

In direct video mode with everything direct connection (mister > hdmi to vga DAC > vga to bnc cable > bvm a14
i get this kind of thing.

https://youtu.be/aeusIwQircs

I also get this sometimes with mister io board. Same problem with other source, even if they could be less noisy the problem is here.

I am testing this with my A14. My A20 didn't work when i receive it, i give it to repair company, and they found a dead solder with a resistor in the video board. The monitor is still currently with the repair company, but when i go to see it we made some test, and noise was exactly the same as the A14 i have home. It was confirm by the electronics, so it's not my imagination. It's very annoying because sometimes it's very noticeable, and you don't buy an expensive A series with a 300$ extension cards to get noise.
fernan1234
Posts: 2175
Joined: Mon Aug 14, 2017 8:34 pm

Re: BKM 68x clone noise

Post by fernan1234 »

Isn't it most likely the cables that you're using to get RGB/Component into the monitors?
atohmdiy
Posts: 57
Joined: Wed May 06, 2020 9:48 pm

Re: BKM 68x clone noise

Post by atohmdiy »

At first i ordered two vga to bnc cable from ebay. Both had the problem, even if i highly doubt, i thought it came from here, so i order two sommer cable vga to bnc, that are suppose to be of great quality. Same problem...
But i finally manage to resolve the issue, at least with my A14.
There is onboard switch in the bkm board for 75 ohm termination. Until now the two sync line where 75 ohm terminated, i put the two switch to pass-through, and i move the card in the other slot. No more noise.
I did try to set the two sync line to pass-through before, but sync wasn't stable, image was jumping every x seconds. It is not the case here, so maybe there is a problem with the card's slot in my bvm, who knows.
I need to do the same with my A20 once i get it back, we'll see.
atohmdiy
Posts: 57
Joined: Wed May 06, 2020 9:48 pm

Re: BKM 68x clone noise

Post by atohmdiy »

I can confirm the behavior is exactly the same with my A20. There is noise unless the card is on the right slot (when you look from the back) and the two sync switch to passthrough. By doing this sync is clearly less stable, with strange behavior, but overall it's fine.
Post Reply