AVPC with GSB-8200 for RGBS to VGA

[Gary from OPA]

About a month ago I bought just the bare GSB-8200 board and today I finally wired to up to my Dijit AVPC card so I could use my 17" Acer VGA monitor.

 

I used the 8 pin hardness and CSYNC from the 6 pin AVPC DIN and doing the Amiga way I placed a 680ohm resistor in line and bang it works I get an nice image.

 

Only two problems the default of 20 for the V-size gives you a frozen image changing it plus or minus gives you a proper image that updates with the normal bit of noise and small tear in the top-left corner. No big deal for bare direct hookup with no shielding or case.

 

My main issue is that every 1 minute like clockwork the GSB cuts out displays "no signal" and black screen then comes back perfectly after about 3 seconds, which of course is pain in the ass.

 

I tried different resistors in the sync line 470, 820, 1k. With 1k giving total lockup and 470 more syncing issues so 680 seems to be sweet spot.

 

I seen that shift838 and others suggest using the LM1381 and building a sync separator, but sadly those seem to be gone and now prepare all doing the gsb- control stuff with a ton of mods etc but shit those boxes cost $200

 

I was hoping I could just do it quick and dirty I seen many on the past with good results using just the gsb8200 by itself on the v9938 and in the msx world so it should work if I don't mind a bit of shaky and a little tear and fuzzy lines.

 

Sadly I waited too long to test this board out so I can't return it to Amazon the cutoff date was Feb 2nd.

 

I see others saying the HD SG-v9900 is good, the new blue board from China but sadly it's only HDMI no VGA so I would need to get an another HDMI monitor, I was hoping to use this VGA monitor as I got many of them. Plus it takes a month to come from China with no returns since they not stocked on Amazon line the gbs8200 is.

 

I guess I could try building a sync splitter but shit those lm1381 parts take a month to come as well.

 

Any suggestions on what I can try to stop this every 1 minute blanking out with no signal displayed, funny thing it doesn't if I just stay messing around in the OSD settings menu.

Edited February 25 by Gary from OPA
more information

[Gary from OPA]

This is the best I can get the stock v4.0 GSB-8200 board working, with 5volt 2amp power supply, and directly wired to my Dijit AVPC v9938 card, using a 681ohm resistor in the CSYNC line and 100ohm resistor across the sync/gnd pins on board, and removing the C11 cap on the 1.8vdo line to make it more stable. And changing the V-Position setting from the default 20 (which produces a frozen image) to any setting between 10 to 19, and now it works, except still every 1 minute it blanks out with "no signal".

 

 

the only old fix i have not tried is this one:

 

https://ramapcsx2.github.io/gbs-control/Wiki/Sync-on-Green-Capacitor-Replacements.html

 

which is removing the two tiny C33 and C35 caps and replacing them with 1nf (the stock is 100nf), they claim that is better for sync, but its old fix, they no longer do it, as i guess it been replaced by software changes. but i doubt i have any 1nf smd caps to try it with anyway.

Edited February 25 by Gary from OPA
more info / wrong cap values

[Gary from OPA]

no luck, changing the caps on the crappy gsb-8200 stock 40 dollar bare board, doesn't help, that all the hardware fixes done as per the gsb-control wiki, without getting into changing the software firmware, so no luck getting the v4.0 board to work right using stock setup. -- strange as in the past people were able to, there must be something a bit different in the stock firmware compared to the older v3.0 and v2.0 gsb-8200 they were playing with back 8 years ago. oh'well that was load of fun for the last two days. -- now to redo my video cable with rca connectors so i can try out this $200 super-duper gsb-control one and see what happens.

[+FarmerPotato]

Gary, the part is LM1881.  I built the same LM1881 circuit as @Shift838 did in the Genie box.  The LM1881 is cheap. 

[Gary from OPA]

22 minutes ago, FarmerPotato said:

Gary, the part is LM1881.  I built the same LM1881 circuit as @Shift838 did in the Genie box.  The LM1881 is cheap. 

Yeah I going to try once that part comes just will take a month or more from China. Eta is April 9th. Too bad shift838 doesn't sell the first genie anymore or the V2 with the wifi to do custom firmware.

 

In the meantime I going to test out this fully tricked out model that cost me 192.50 cad to get and hopefully in time the lm1881 comes I can return this costly one and use my cheap board as I don't need all the bells and whistles.

 

Just strange that the onboard sync separater doesn't work right it should. It works great except ever 1 minute it blanks out. I read it's maybe because I using 60hz ntsc system and it's designed stock wise only for 50hz.

[Shift838]

3 hours ago, Gary from OPA said:

Yeah I going to try once that part comes just will take a month or more from China. Eta is April 9th. Too bad shift838 doesn't sell the first genie anymore or the V2 with the wifi to do custom firmware.

 

In the meantime I going to test out this fully tricked out model that cost me 192.50 cad to get and hopefully in time the lm1881 comes I can return this costly one and use my cheap board as I don't need all the bells and whistles.

 

Just strange that the onboard sync separater doesn't work right it should. It works great except ever 1 minute it blanks out. I read it's maybe because I using 60hz ntsc system and it's designed stock wise only for 50hz.

I have the V2 boards in stock, they have not been added to the new site yet.

[Gary from OPA]

21 hours ago, Shift838 said:

I have the V2 boards in stock, they have not been added to the new site yet.

Ok thanks I was able to get Amazon to return the crappy bare stock gsb8200 anyway now I am trying the supped up gsb-control version from retro scaler which has lm1381 in it but not much better at least on the AVPC it works better infact with the sync separater turn off. At least the blank out totally every 1 minute is gone but now there is a small jump every now and then and some white noise in the background.  Also the web interface is a little weird hard to change settings and once I enabled developer mode it seems to lost some settings no longer showing what is turned on and off even after disabling development mode.

 

Any suggestions for what I can try or what settings should be?

 

 

Edited February 28 by Gary from OPA
removed video atariage doesn't like my pixel 7 camera videos

[Gary from OPA]

playing around with that $200 retroscaler gsb-control box.

 

i tried some other vga monitors, no luck either non-supported or worse - tried the hdmi out, still the same jumpy now and then.

 

one thing i noticed if the background on the screen is black, and text grey, there is no jumping, games that use black background seem to work fine.

but the default ti99 of cyan background for BASIC programming more, or the default of dark BLUE with WHITE text in 40col/80col TEXT editors causes the most jumpy picture.

 

maybe need to tone down the RGB settings? -- Auto Gain on/off doesn't help. - i have to do some more reading thru the forums to see if anyone mentions it.

[Shift838]

21 hours ago, Gary from OPA said:

Ok thanks I was able to get Amazon to return the crappy bare stock gsb8200 anyway now I am trying the supped up gsb-control version from retro scaler which has lm1381 in it but not much better at least on the AVPC it works better infact with the sync separater turn off. At least the blank out totally every 1 minute is gone but now there is a small jump every now and then and some white noise in the background.  Also the web interface is a little weird hard to change settings and once I enabled developer mode it seems to lost some settings no longer showing what is turned on and off even after disabling development mode.

 

Any suggestions for what I can try or what settings should be?

 

 

I no longer have an AVPC to do any testing but when I did have the AVPC it was a very simple circuit and produced solid results just with the LM1881.

 

I am using a LM1881 circuit on my Geneve KVM I designed and it works great, but I did have to incorporate a resistor on the CSYNC line heading to the SCART output and 3x220uF electrolytic caps on the RGB lines going to the SCART out to produce a very stable and no screen shake on any colors combinations.

 

csync ---75OHM---output

 

R    ----+||----Output

G    ----+||----Output

B    ----+||----Output

 

Might want to give that a shot..

[Gary from OPA]

29 minutes ago, Shift838 said:

I no longer have an AVPC to do any testing but when I did have the AVPC it was a very simple circuit and produced solid results just with the LM1881.

 

I am using a LM1881 circuit on my Geneve KVM I designed and it works great, but I did have to incorporate a resistor on the CSYNC line heading to the SCART output and 3x220uF electrolytic caps on the RGB lines going to the SCART out to produce a very stable and no screen shake on any colors combinations.

 

csync ---75OHM---output

 

R    ----+||----Output

G    ----+||----Output

B    ----+||----Output

 

Might want to give that a shot..

The retroscaler box I have now includes the lm1381 circuit and turning it off and on didn't help.

 

I tried both a 470ohm and 681ohm in the sync line as recommended by others but that didn't change anything either.

 

The AVPC should already have caps on the RGB lines like my TIM did but I will double check.

 

Here is a video I uploaded to twitter the recently you can see it shake a bit on cyan title screen and in programs with a blue background but with black background it's perfect. (weird, still can't upload videos to atariage, uploads fine, and displays fine, and then few minutes later, switches to unsupported mime type, so he is link my the video on my twitter post:

 

 

 

 

Edited February 28 by Gary from OPA
video upload not working, so link to twitter

[Shift838]

almost looks like your sync line is not stable and then comes back.  I have the same GBSControl device you are using and have used it with no issues on both my Geneve and an Atari ST, wondering if you have an issue with the GBSControl device itself.

 

 

[Gary from OPA]

2 hours ago, Shift838 said:

almost looks like your sync line is not stable and then comes back.  I have the same GBSControl device you are using and have used it with no issues on both my Geneve and an Atari ST, wondering if you have an issue with the GBSControl device itself.

 

 

Do you remember all the settings you used for it on the geneve and any special wiring you did.

 

I added clipon ferretic beads to all 6 rca lines and the power line and the audio out and changed to another monitor and switch up to using HDMI to dvi instead on it and it's more stable now on my AVPC card with it now only flicking now and then when the background is cyan like on the title screen but now the flicker is gone when white text on a blue background line in funnelweb or the horizon menu.

 

It seems the issue is not perfect 60hz watching the LCD screen on it it flickers when it goes down to 59.20hz normally it at 59.69hz

 

Some VGA monitors I tried will not even accept the signal at all since it's not 60hz.

 

I wonder if it would help to modified the avpc and use the composite video with sync and turn on the sync stripper on the box instead. I guess I could try temporarily without the green as when you move the jumper green becomes cvbs.

[Shift838]

let me pull the gbscontrol back out and get it hooked up.  I moved it to my ST before I bult a ST2VGA adapter and I changed various settings there to get it to look right.

 

not sure if I have a Geneve setting saved on it or not, if not I will fiddle with it to get the settings and get back to you over this weekend (hopefully)..

[Gary from OPA]

19 minutes ago, Shift838 said:

let me pull the gbscontrol back out and get it hooked up.  I moved it to my ST before I bult a ST2VGA adapter and I changed various settings there to get it to look right.

 

not sure if I have a Geneve setting saved on it or not, if not I will fiddle with it to get the settings and get back to you over this weekend (hopefully)..

Ok many thanks. If only February had 31 days we would have enough time to get everything done. At least this leap year day helped.

[Gary from OPA]

The other cheap Chinese RGB to VGA board arrived today and I did a quick test just wire harness without a solid nice cable and it produced a rock steady picture without any messing around or changing any settings. Only thing is I had some ghosting of black outline behind the letters on the ti title screen, but I think that due to no shielding and my quick test side harness instead of making a solid perfect cable. I going to that on Friday and run some more tests with luck I can keep this 31 dollar board and return the 200 retroscaler box. It seems this other Chinese brand which not as popular as the gsb8200 handles syncing better. Mine arrived with a heatsink so if this one worthwhile keeping I will need to add that as well plus some good shielding on the bottom with a case.

 

 

[Serafini Lapo]

2 hours ago, Gary from OPA said:

L'altra scheda cinese economica da RGB a VGA è arrivata oggi e ho fatto un rapido test solo del cablaggio senza un cavo solido e bello e ha prodotto un'immagine stabile come la roccia senza fare confusione o modificare alcuna impostazione. L'unica cosa è che avevo qualche traccia di contorno nero dietro le lettere nella schermata del titolo, ma penso che a causa dell'assenza di schermatura e del mio cablaggio laterale di prova rapida invece di creare un cavo solido e perfetto. Ci andrò venerdì e farò altri test, con un po' di fortuna posso tenere questa scheda da 31 dollari e restituire la scatola del retroscaler da 200. Sembra che quest'altro marchio cinese, non così popolare come il gsb8200, gestisca meglio la sincronizzazione. Il mio è arrivato con un dissipatore di calore, quindi se vale la pena tenerlo dovrò aggiungere anche quello, oltre a una buona schermatura sul fondo con una custodia.

 

 

Um, if I may ask, where did you purchase this Gary? Thank you👍

[Gary from OPA]

1 hour ago, Serafini Lapo said:

Um, if I may ask, where did you purchase this Gary? Thank you👍

I ordered it from Amazon

 

https://www.amazon.ca/gp/aw/d/B0CQYMNFQY

[Gary from OPA]

Made a video of this new Chinese HD video converter board running that not a gsb-8200 going to return the 200 dollar RetroScaler as this new board producing the best picture yet, totally rock steady no matter the colors, no lag, the text is clear to read in 80 column mode. That is all I need now I can enjoy my v9938 avpc in my life monitor and edit and work on my coding without my eyes getting tried from fuzzy letters or the image jumping every now and then or totally blanking out for a few seconds.