Slight ghosting in STe RGB output

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Slight ghosting in STe RGB output

Postby thgill » Sun May 09, 2010 8:10 am

Just received a NTSC 520STe with 4 megs ram installed.

Machine seems to work fine except a bit of ghosting on the RGB port. Connected to a SC1224 monitor (picked another one of these up).

My 1040STf works perfectly on the SC1224, just my STe has a ever so slight ghosting. Usually only noticeable on the GEM desktop or when there is lots of small text on the screen.

Ideas?
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Re: Slight ghosting in STe RGB output

Postby nativ » Sun May 09, 2010 8:20 am

Hi,

I occasionally get this on my STe while using 'High Resolution'. It's normally the cable not seating properly in the monitor port. Reseat! or plug in again! :O) Is my solution. I might also try expanding the outer tim of the cable head to stop slippage from the port.


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Re: Slight ghosting in STe RGB output

Postby thgill » Sun May 09, 2010 8:31 am

Mine is doing it in Low res.

I have checked the monitor cable several times.
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Re: Slight ghosting in STe RGB output

Postby nativ » Sun May 09, 2010 8:43 am

thgill wrote:Mine is doing it in Low res.

I have checked the monitor cable several times.


It's the same port for High and Low! :D

Do you have another cable?

Is it doing anything similar via RF?

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Re: Slight ghosting in STe RGB output

Postby thgill » Sun May 09, 2010 2:23 pm

I replaced the cable on the monitor. Same result.

I haven't tried the RF output yet.

Just odd my STf is perfect with this monitor.


My STe has all its internal shielding. The ghosting almost looks like interference. Is the STe machines more
vulnerable to RF noise than the older machines?
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Re: Slight ghosting in STe RGB output

Postby lavaburn » Sun May 09, 2010 2:45 pm

Are we using high-quality cables, guys?

You'll get ghosting and interference if the RGB cable is made of doorbell wire. :wink:

When I set my STe up recently, I decided to make my own RGB cable to connect it to either my Commodore 1084S, or the Philips CM8833-MkII. All I had, cable-wise, was a piece of overall-screened multicore wire. In other words, the individual wires weren't screened from each other (this is the important part) - just all screened as a whole from the outside world.

[In case I'm not understood here (sorry if I'm being confusing! :(), "screening" is the braided hair-like wire, sometimes coupled with a tin foil-like material, that's wrapped around the wire and shields it from interference.]

It worked, the picture was stable and sharp, but there was ghosting, especially on highly contrasting colours, and text etc. I also had some strange interference from the floppy drive motor; when the drive was accessing a disk, the screen would get some rippley interference - not nice! :(

So, later on I was given a spare VGA cable, a very thick one. Thick cable is a good clue to the cores being individually screened from each other. Chopped the ends off, found four individually screened cores; one for each colour, and a nice screened sync, too, the few remaining wires left for monitor data and extra sync signals in its original VGA application. Stripped the wires down, twisted all the screens together and soldered them to the plug connectors' bodies at both the D-sub and 13-pin DIN ends, and connected up each line. I used a few resistors to suppress the color signals down a bit as recommended in a few guides for making 1084S/RGB cables.

Ghosting's practically gone, picture is lovely. :) No more floppy interference either - so the crosstalk between color signals is eliminated.

However, I do get some very minor interference, not just on the screen but also on the audio. I have a feeling that it might be remedied when I get around to re-capping my power supply, which I hope to do soon. I think the power supply has a part to play in suppressing noise, so when it's capacitors are old and dry, it cant work as well to supply a good clean signal. A while ago I was probing the power supply with an oscilloscope and found the same interference I was getting on the audio outputs inside the PSU too, so hopefully a good service with new caps and other components should sharpen the machine right up.

Just some of my experiences... I hope you manage to find a remedy, dude. :) Stuff like this does annoy me too, and takes away from the enjoyment of these old machines. :(
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Re: Slight ghosting in STe RGB output

Postby thgill » Sun May 09, 2010 2:56 pm

I am using the same cable thats built into the SC1224. I had another SC1224 that kicked the bucket so I removed the cable from it and installed into this monitor. Made zero difference. Its a shielded cable.

If I unplug my STE and plug in my STf the video is sharp and perfect.

Problem ONLY appears to be with the STe.


I wonder if the power supply is the culprit? Would I be able to use the power supply from my STf in my STe?
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Re: Slight ghosting in STe RGB output

Postby lavaburn » Sun May 09, 2010 3:09 pm

Ahh sorry. I didn't realise the model of monitor you were using had built-in cables, I'm only familiar with Commodore ones being primarily an Amigan :oops:

STf has no modulator, does it? I have wondered about the possibility of the STE's RF modulator being a culprit for noise. I've been tempted to desolder it, as I have no use for it at all... I wonder what other peoples' opinions on this are.

As for the power supplies, I would have thought so, but I don't know about the STf's power supply connection, I wonder if it's the same. Could be a good idea to have a look and if possible, try, though as I'd be interested to find out whether an unhealthy power supply can induce noise into the AV signals. :)
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Re: Slight ghosting in STe RGB output

Postby DarkLord » Sun May 09, 2010 9:25 pm

Hmm, my SC1224's cable has a snap on device that came with it - it appears to be
some sort of magnet? It is supposed to help with interference I believe...

Perhaps you need something like that?
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Re: Slight ghosting in STe RGB output

Postby lavaburn » Mon May 10, 2010 5:53 am

Ferrite cores:

http://www.google.com/products?hl=en&q= ... 1&oi=spell

Could be a good idea for choking RF interference travelling down the cable before it reaches the monitor. :)
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Re: Slight ghosting in STe RGB output

Postby DarkLord » Mon May 10, 2010 10:14 am

Thats it - I couldn't remember the name - thanks! :)
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Re: Slight ghosting in STe RGB output

Postby thgill » Mon May 10, 2010 1:00 pm

I might pick up an RF choke today and snap it on the video line and see if that make a difference. Radio Shack sells them for $6.

Since the STf doesn't have this issue, I'm not sure if it will have any effect on the STe's issue.

Going to also swap power supplies tonight and see what effect that has. I have read several threads here at the Atari Forum with both ST and Falcon owners
that had various issues with the video (corruption artifacts or flashing video when accessing the floppy drive) that was resolved by replacing the psu or upgrading components in it (caps and such).

Its just such a rare find here in the US to find a NTSC STe machine and I really want it to work perfect.
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Re: Slight ghosting in STe RGB output

Postby thgill » Tue May 11, 2010 3:18 am

Ok, swapped out the psu from my STf and it made no difference at all. Tested both power supplies in my STf and the picture was sharp and crisp.

However on my STe it just isn't as sharp as on my STf. Very light ghosting and a very slight waviness to the picture. Mostly detectable during an all white screen like when the machine is powered up without a floppy in it and its waiting to load GEM desktop. The picture isn't bad...just reminds me of high quality composite or s-video. Just not RGB clarity and sharpness.


Here is my questions:

Is there some known issue with STe machines and the SC1224 monitor?

Is the RF Modulator perhaps causing this? I know a lot of the folks in the Atari 8 bit scene report on their machines that removing the onboard RF modulator cleans up their Svideo and composite video signal.

Anyone with both a STf and a STe compare their RGB video outputs?


Bottom line is that my non RF modulator having 1040STf has superior RGB video to my 520STe. Thats a shame and I would like to sort it out.


Also, while I was under the hood of STe I made a couple discoveries. It has the good DMA chip. Probably a UltraSatan is in my future.

Also, it has an ICD 16MHz Adspeed STe in it!! :D The jumper is still set to 8 MHz on it. I was reading the manual online and it mentions installing a switch to control if the machine is in 8 or 16 MHz mode. There is suppose to be some software that can also control this. Anyone have a link to it?
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Re: Slight ghosting in STe RGB output

Postby DarkLord » Tue May 11, 2010 8:48 pm

On my 16mhz Adspeed equipped Mega ST (not e), it boots up in 16mhz mode, and there
is an ACC that lets you switch speeds "on the fly".

On my setup, there isn't any additional hardware switch.

There is also a nice listing method to have it automatically switch speeds on incompatible
software.

If you can't find it, lemme know and I'll zip it up and post it here.
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Re: Slight ghosting in STe RGB output

Postby thgill » Wed May 12, 2010 2:17 am

If you wouldn't mind posting that software. Perhaps its compatible. God knows I have searched high and low for it.


Also, picked up a RF choke today for the monitor cable and a couple of the "cheater" ungrounded plug adaptors to use on the monitor and STe just in case there was some kind of ground loop issue. Neither seemed to make a difference. :?


Anyone have any suggestions?
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Re: Slight ghosting in STe RGB output

Postby DarkLord » Wed May 12, 2010 9:14 pm

thgill wrote:If you wouldn't mind posting that software. Perhaps its compatible. God knows I have searched high and low for it.


Also, picked up a RF choke today for the monitor cable and a couple of the "cheater" ungrounded plug adaptors to use on the monitor and STe just in case there was some kind of ground loop issue. Neither seemed to make a difference. :?


Anyone have any suggestions?


Wrong message thread to do this in so look for a new topic where I'll try and upload the ADSpeed software. :)
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Re: Slight ghosting in STe RGB output

Postby thgill » Thu May 13, 2010 3:27 am

After some further research, is it possible that I have some failing capacitors on the STe's motherboard?

When I had it opened I didn't notice any that stood right out as problems, but I wasn't looking that close at them.

If it is the caps, do I need to replace them all (looks like there is a hell of a lot of them) or just ones pertaining to the video section?
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Re: Slight ghosting in STe RGB output

Postby thgill » Fri May 14, 2010 7:52 pm

Something just dawned on me.

My "tested good" psu that came in my 1040STf might not be as good as I had thought. I had forgotten about it, but in my STf machine, when ever a floppy disk is accessed, the screen flashes. The floppy drives light on the keyboard also doesn't work (could be keyboard related though). This is a TOS 1.0 machine.

I have been spending all day researching the issue on my STe problems and I have ran across posts talking about failing power supplies and if the 5v rail is low then when the machine accesses the floppy, it will take away power from the machine hence the flashing screen.

Is it possible that 2 bad power supplies will exhibit 2 different sets of symptoms in 2 different model machines?

Floppy drive access strobes the screen in the STf and general bad looking video in the STe (yet no flashing screen with floppy access).

It could be that while both power supplies work, they are starting to fail due to capacitor or rectifier issues and exhibiting different issues in both machines.


Does this sound reasonable?


Tonight I think I am going to take apart my STe and wire up an ATX power supply and see how it fares. Hopefully that will once and for all let me know if the power supplies are faulty. Anyone with a source for the connectors used on the ST power supplies that plugs into the motherboard? I would hate to cannibalize once from a fixable psu.
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Re: Slight ghosting in STe RGB output

Postby DarkLord » Fri May 14, 2010 8:42 pm

Hey, just thought I'd mention that the last PS that failed in my Mega ST did something
similiar...

Machine would boot up, and run fine - ran my BBS for hours and hours no problem.
Just as soon as you dbl-clicked on the floppy icon and tried to access a floppy disk
though, the whole machine would reboot.

Someone explained to me that was because the floppy was actually one of the
biggest voltage "hogs" in the system.

So I dunno - if you're gonna rule anything out though - you're gonna have to have
hardware thats beyond a shadow of a doubt good to use as a baseline to check.

Otherwise all your results could be buggered.

Its tough sometimes - like working on a new car nowadays - they put it on the computer
for you, tell you it could be 1 of 6 things. So you start replacing stuff - and its usually the
last thing you replace. :(

Anyone near you that could loan you a "for sure" good PS?
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Re: Slight ghosting in STe RGB output

Postby simbo » Sat May 15, 2010 9:49 am

using an st psu with an ste is a bad idea
there is insuficient current avalible on the 12v rail
as the ste 12v rail also has to supply the opamps
and other 9v stuff via another regulator onboard
i havent looked at the rating's

video problems like this
are usualy caused by things like
badly seated gstshifter or the chip's pins have become corroded
or grown lead crystals building up a resistance {usualy ground pins}
bad bridge rectifier on the psu just change it anyway for a 2amp type
dry joints on the underside of the psu board
bad capacitors on the psu or on the main board
there is a large resoviour capacitor on the main board
and the ones on the main boards dry out just as much as the psu ones
especialy in hot or humid countrys
so change all the caps around the video area
its also not unknown for several st's in a collection
to all suffer from the same bridge rectifier problem
bad mains supply is the usual problem {bad earthing usualy to the whole house}
youll find a topic about it in the guides section

and after you change them and clean up the psu and blood of the machine
youll find less fuzz for sure
then use a mains conditioner unit {you can get them from any computer shop}
you can also find there is a leaky ceramic capacitor that couples the two sections on the psu together
i usualy replace ALL the capacitors on the psu if there is a problem like this
the bridge rectifier and the main cable and clean the mains socket
sometimes you even need to either change or take appart and clean the mains switch

and make sure the metal peg is inplace under the floppy drive to connect its shielding
i add a wire from the case of the floppy to the main metal screening
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Re: Slight ghosting in STe RGB output

Postby thgill » Sat May 15, 2010 9:07 pm

I think I am going to replace the rectifier and all the caps on the psu and all the caps on the motherboard. Plus extract and reseat the shifter.

Is there a list anywhere with all the needed caps for the psu and motherboard?
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Re: Slight ghosting in STe RGB output

Postby Lando_C » Sun May 16, 2010 7:09 pm

I too, just picked up an STe with this problem, ghosted video in both high and lowres, and blinky/noisy/snowy picture when accessing floppy. I previously had a 520ste that did the same, and that turned otu to be a weak psu, all went away with another one. Tis seems to be a standard problem.
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Re: Slight ghosting in STe RGB output

Postby simbo » Wed May 19, 2010 12:50 pm

there are quite a few good faq's in the posts and guides sections

as for lists there is too many psu varients too make a good list
best to mark each parts positions with an indelible pen number them and the board
then remove them all buy and match as needed
if you need help identing stuff just take a 300k or less photo and post it here as a jpg
then we can circle what to replace as the usa version will differ from the euro version im sure


most caps you can get on ebay or from in the usa i think circuit or some local places
a good thing to do is visit a small tv repair shop and ask for help

just replace every capacitor and resolder all the joints
by removing the old stuff and replace it clean pins as needed with a burnish fibre pencil
get them on ebay cheep great for cleaning pins of chips also
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Re: Slight ghosting in STe RGB output

Postby thgill » Tue May 25, 2010 10:39 pm

I haven't had a chance to replace the capacitors yet, but I have noticed some other things.

I have noticed some pops and clicks in the stereo audio output when I play back, for example, a mod file, I notice some occasional pops and clicks. Seems to be most prevalent in the left channel. I have tried different cables and speakers with the same result. But the odd thing is that I don't hear the same clicks in the left channel when I play back chip music. I first thought maybe the left audio jack was going bad/poor ground, but I don't know now. Perhaps just the nature of chip music is masking pops and clicks that are still occurring the left channel?
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Re: Slight ghosting in STe RGB output

Postby simbo » Wed May 26, 2010 9:56 am

i think there is a need too look for a bad cap

as Ill say again

too many people just replace the electrolytic and tantalum even ceramic capactitors
in the psu with retros
why i dont know ??? :coffe:
the problem is every capacitor has potential too cause problems clicks {internal shorts }
as caps are made of folded/circlick layers of metal films
as they change there resistance
usualy damaging the plates with carbonites

so bascialy if you want a click free voltage setup
{first monitor with a trigger scope setting using a scope you can find the cap that has issues}

ive found caps in older specys that cause memory not to appear
single chips
as most atari st even ste has single chip bypass decoupling caps
it makes sense to replace ALL caps now!
in atari past 2000 X
if you really want to preserve it
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