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VBXE


lotharek

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I'd like to try your VBXE and I'm not too far from you. What kind of monitor would I need?

 

Bob

 

 

 

Time to punt.

I installed a new RF modulator. Still can't get an image out of my 130XE VBXE.

 

Last request effort before I sell it off or part out the good bits: anybody for hire to debug/fix/finalize my installation?

 

Or, anybody have for sale a 130XE w/ a VBXE installed?

Thanks,

-Jason

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Hi Bob-

 

To clarify, was your post aimed at me? I'm in Los Angeles, CA. My 130XE, with its faulty VBXE installation, is currently in Houston, TX, taking its sweet time to get to the UK so that flashjazzcat can inspect it, roll his eyes, shake his head, perform a facepalm, & take a stiff drink before he determines if he has the courage to undo & redo what I have done.

 

If & when he can salvage it & the post office returns it to me in one piece, I'm happy to show it off.

 

Thanks,

-Jason

 

 

I'd like to try your VBXE and I'm not too far from you. What kind of monitor would I need?

 

Bob

 

 

 

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I had the exact same issue (periodic flickering) with - at the time - my chosen display device, an LG M227WD LCD TV. This was before I did the gated sync mod, which in that instance fixed it. But Candle had previously suggested another mod which also worked. Trouble is, I took the mod to bits and can't remember how it worked.

 

Basically, its purpose was to attenuate the sync signal, which (according to Candle) was perhaps a bit strong. I can tell you the components: a three-legged variable resistor, and 10uf electrolytic capacitor.

 

...never mind - found it:

 

http://atariage.com/forums/topic/142283-vbxe-2/page-32?do=findComment&comment=1917871

 

:)

 

Hi Mr JazzCat - I have news, discovered variable resistors are called Potentiometer's on maplin's website, bought 3 of them today to test 100ohm, 500ohm, 1K ohm

 

This is the 500ohm, http://www.maplin.co.uk/p/500-andohm-cermet-horizontal-preset-potentiometer-wr39n

 

The 1K ohm seems to make the picture more stable but only slightly, I notice when I turn the dial to the far right (clockwise) it seems to stablise "ish" just before the signal is lost.

 

I have wired it as follows, Pin 15 going into pin9, sync from pin 10 goes - 10uf cap, + end to left terminal of potentiometer, middle pin goes to monitor jack, right pin is ground.

 

CD4050usepin10with10ufandvaraiableresist

 

I'm wondering as these resistors are not giving me a fine enough control, what do you think?

 

thanks again...

Edited by mjsaville
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Okay, I'm taking sync from pin 15 rather than pin 10, I can get the image stable (picture quality is superb), every 5 to 6 mins the picture gets a right shift by say 5mm then returns to normal positiion at the same time the sound seems to cut out too. This I think I can live with but here's the thing:-

 

Playing DropZone for the last 20mins or so and the picture shifts from left to right as mentioned above (No problem can live with this), then I decide to play Super Zaxxon and the screen is shifting right then left not every 5-6mins as per DropZone but every 10secs or so.

 

I'm wondered if the XE is using different screen mods for different games, does this then effect the setting / adjustment on the pot?

 

I'm not the type of person to adjust the screen for every game I play. I have also tried using the vga port on the tv rather than scart but the Samsung has sensing electronics and when the atari is turned on the tv turns itself off - so I have abandoned this option.

 

I'm getting the feeling we have just about gone as far as we can with this, but super frustrating nearly thrown the machine down the stairs a couple of times today.

 

Any more idea's Mr Jazzcat?

 

thanks again.....

 

MJ

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Do you have any other SCART-equipped monitor or TV to test with? The more modern displays seem far fussier than the older ones.

 

Failing that, Candle or Lotharek might be the boys to consult.

 

No worries mate...

 

I have 3 other LCD's I can try.

 

I also have a 65XE and an 800XL so may desolder the board and swap it into one of these (Soldering skills are not too bad at the moment (( plenty practice))). I just picked the 130 because of the demoscene would make use of the vbxe and the extra memory.

 

thanks again for all your help and fast turnaround on idea's :) :) :) :) . I may also just live with it in stock composite video form - it's still a million miles better than the original screen quality.

 

I'll post back if I come up with anything more info though.

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Any more idea's Mr Jazzcat?

It may be unrelated, but in which position is the PAL/NTSC master clock jumper on the VBXE? I just remembered while working on one today that the dual-crystal boards I've seen have the NTSC and PAL labels reversed, so you should put the jumper in the NTSC position if you want to install the board in a PAL Atari and vice-versa.

Edited by flashjazzcat
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  • 4 weeks later...

 

It may be unrelated, but in which position is the PAL/NTSC master clock jumper on the VBXE? I just remembered while working on one today that the dual-crystal boards I've seen have the NTSC and PAL labels reversed, so you should put the jumper in the NTSC position if you want to install the board in a PAL Atari and vice-versa.

Hi Mr FJC,

 

Apologies I have been away with work so no time to tinker with the Atari, just been on it.

 

Glad you mentioned the PAL/NTSC master clock jumper's being reversed as I only get an image when its on NTSC which mean's it PAL which is what my Atari is.

 

Okay, things I have tried since I last posted,

 

(1) Tried a different CD4050 chip from an 800XL, made no difference.

 

(2) Desoldered the CD4050 and replaced it with a CD47HC4050 chip (Found after googling and reading about an Atari VCS mod) apparently its a faster version of the CD4050, which gives me a more stable image when taking csync off of pin15, however the board is still providing artifacts on the screen. Fine on blue boot screen when I load VBXE game Nightshade there are artifacts on the bottom left of the screen. If I run the output back through gate Pin 9 and take the output from pin 10 it is still a little cleaner but still not great.

 

(3) Do mod number 2 above, then putting a 100nf cap across the connection to gnd doesn't really improve the situation, the picture deteriorates if anything. Still using Nightshade game as a benchmark for image quality - not sure if this is sensible or not.

 

(4) With the CD47HC4050 installed and i take comp video from the monitor port, then use a 100nf cap to clean the image, Yes the grainyness goes but then you load nightshade and the black parts of the screen look like a "Car Crash", 200% more artifacts.

 

I will tinker a bit further over the weekend.

 

MJ

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  • 3 weeks later...

Installing vbxe in my 130xe. I was reading the installation pdf from lotharek's site and I got to this picture:

 

VBXE2.jpg

 

This is not the correct way to place the vbxe on the adapter correct? Why did they put that picture in the installation manual?

Edited by TheNameOfTheGame
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I have my vbxe installed. I tested it first with just the lower board with antic after installing the socket and it worked ok over monitor output.

 

After inserting the vbxe board and wiring it up, a red led lights up when I power on, but no output on the monitor using the monitor output.

 

I'm guessing that when the vbxe board is installed, the monitor output is disabled and I have to go through the vbxe output pins?

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No - the built in monitor and TV outputs shouldn't be affected.

 

You need to ensure the connections and build procedure is done properly.

Particular importance is the clock crystal which is different depending on what machine it's for. The built in clock is usually replaced by one onboard the VBXE, and you take it from the relevant pin, IIRC it's 14 MHz for XE but 3.59 MHz for earlier machines.

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Hmm, ok I must be doing something wrong. Here is my install:

 

vbxe2.jpg

 

 

Is it ok to take both J3 and J6 GNDs from freddie's GND pin 20? Also I took J1 pin 8 and jumped it to the VB pin on u1mb like the install document said. The other connections are pretty straightforward.

 

Anything stand out as wrong?

 

 

**EDIT** I removed all the jumpers from the VBXE and it booted fine from monitor output. I powered off and plugged in each header one at a time. Everything worked up until I plugged in J6 header which has 14MHz clock from freddie pin 2. Then I got blank output.

 

Edited by TheNameOfTheGame
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Shared GND should be no problem.

Also I believe U1Meg allows selecting VBXE Off, D6 and D7 - normally you'd have D6 but that's something to worry about later. Having it turned off only means programs can't access it, the VBXE will still be functioning and outputting to monitor.

 

I'd be going carefully through instructions, especially relating to clock. IIRC VBXE has clock outputs as well so don't get them mixed up.

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