800XE vertical lines composite

[+mytek]

I think to sum this up, if replacing that capacitor makes things better as far as noise in the video is concerned, then that means the original had gone bad. Reason for the original cap failing can be chalked up to age, inactivity, or damage caused by the stress of physical manipulation (likely bent too far side to side). When replacing said capacitor, the pitch (lead spacing) should match the board, capacitance should match the original (10 uf), and the voltage just needs to be a safe margin above 5v which 16v definitely is. Things such as the reforming voltage, although it might play a role in the ultimate life, probably won't matter since any new capacitor close to the original spec will outlast any of us unless you are still in your teen years (that counts me out).

 

Bottom line as has been already pointed out, a higher voltage rating than the original part is not required, nor will it work any better because of it. However due to better efficiencies in newer designs you might find that a newer 16v part is both smaller in size and pitch as compared to the original capacitor. Thus a higher voltage newer version might match the old one's pitch and be a better fit which will prevent damage when inserting it into the board. And lastly as Gunstar pointed out, if the pitch is too small don't force it into the board, but instead reform the leads to fit properly as he described.

 

And lastly let's not kill the messenger who has possibly pointed out a valid fix for the vertical lines issue that has been such a long standing problem on the A8. He might have simply used the higher rated 25v part because it fit better in the original hole, although his statements about safety related to this are really a non-issue.

 

[tane]

 

 

[+mytek]

I'll add one more thing to the issue of mismatched lead spacing, known as pitch. Measure the hole spacing in the motherboard with calipers, and try to match this spec when ordering the new component. Mouser and Digi-Key usually have this listed on the order page under specs, and other vendors such as Jameco provide the datasheet where the information is provided. Basically do your research before ordering.

 

Don't ever force the wrong pitched part into a board such as the previously posted image suggests with the angled leads. If the lead spacing isn't a match, then either reform the leads carefully by making a series of bends in the leads with needle nose pliers, or just get the correctly pitched part in the first place (better).

 

 

[tane]

36 minutes ago, mytek said:

Basically do your research before ordering.

Outside America, China or any other manufacturing country, you have to get used to what is available in sites with free shipping options, like AliExpress. If there isn't a huge demand in a place, there isn't a huge variety of products.

 

At Mouser:

  

 

 

 

Edited July 4, 2019 by tane

[_The Doctor__]

13 hours ago, Gunstar said:

I see, I just naturally bend the legs at about a half-centimeter from the bottom of the cap, if they are not at the same pitch, to match the pitch and make them parallel, before I ever try and insert them. Of course I have never tried to insert a cap so it is flush with the mobo, I always leave at least a half-centimeter between the bottom of the cap and the mobo, if there isn't enough head-room, I carefully bend the cap over, but that has rarely happened, and in fact, when I am working on a circuit board, I make sure all caps and anything else on legs are all standing as vertically straight as possible, especially if they are close to other components, so nothing is touching. More to make it all look nice and neat than anything else, but I like to make sure every component has as much breathing room as possible.

and in fact, during some of my work, stand offs, spacers etc. were required between caps, transistors and other such components and the PCB. Vibration, temperature extremes, and other forces acting on the components would lead to failure otherwise.

[Gunstar]

 

This capacitor is going on the Power board for my 1084S-P. All the new capacitors are about half the size of the originals.

 

 

Old and new (installed) 

200V 220uf capacitors.

 

Edited July 5, 2019 by Gunstar
improved image

[Simius]

I would recommend using an MLCC SMD capacitors instead all electrolytic except 470uF/16 next to the power switch. 10uF or 22uF 10V 1206 are easily available and cheap.

[universal2600]

I've also found if using the stock video from the din, replacing the cd4050 can also help aswell, I use my xl with composite and after swapping it out, the line are much fainter, I'll try swapping out the cap aswell

Edited May 27, 2020 by universal2600

[universal2600]

The cap didn't make much difference, though after some figuring, I've noticed power supply noise can also cause jailbars, I use 2-3amp USB chargers and my authentic apple 10w supply produces way worse jail bars, and it's being filtered (USB cord goes through an emi filter and the atari plug on the other end), I have an 800xl ntsc, also with an internal Newell 256k(board is 1985 copyright), I've also noticed if I touch c53 also can affect the jail bars, which I believe is a 40pf ceramic,  I don't have any 40pf atm so I'll have to swap out that one when I get ahold of some, plus the vertical bands are more pattern like, they show up in groups and look like the gtia test program, I've noticed turning the color pot changes where onscreen the bands appear, it's only noticeable on the basic screen, I don't see/notice it much when running demos or games

 

This unit is pretty early, low serial #366x1 where x is rubbed off, so it'd probably be good to check the caps, I swapped in the newer antic, and added dual pokey aswell the (original) chips are dated first half of '83 ?

Edited May 27, 2020 by universal2600

[+bob1200xl]

So, what are we talking about here? Those vertical bars are generated when the memory goes to REFRESH mode. This transition draws current from the power supply. That current is sharper and faster than the power system can follow, so we get a little 'glitch' in the video output. You can change things in the power system, like filter caps and bigger ground wires and your video may clear up. Or, maybe not completely.

 

So, let's attack the video end. These glitches are extra sharp - they have trouble travelling thru co-ax intact. The monitor may not process them well. Change either and you may be good. You are supposed to have a 75 ohm source in the Atari, transmitted thru a 75 ohm co-ax, to a 75 ohm load in the monitor. I doubt many systems do that.

 

So, all you guys are right, just not on other people's machines. Lots of probabilities. Lots of 'fixes'...

 

Bob

 

[shoestring]

3 hours ago, universal2600 said:

The cap didn't make much difference, though after some figuring, I've noticed power supply noise can also cause jailbars, I use 2-3amp USB chargers and my authentic apple 10w supply produces way worse jail bars, and it's being filtered (USB cord goes through an emi filter and the atari plug on the other end)

They can and they will, switch mode is inherently very noisy. They're not suitable for continuous use because they're not designed to filter switching noise sufficiently, all they need to do is charge.

 

I'd say your filter needs a tweak. I used a DC-DC buck module in a power supply that I rebuilt which has some filtering but I could still see 150+mv of AC ripple on the 5v line under load, added an additional low ESR capacitor and a choke brought that noise down to around 30mv and cured the jailbar effect. 

Edited May 28, 2020 by shoestring

[universal2600]

13 hours ago, shoestring said:

They can and they will, switch mode is inherently very noisy. They're not suitable for continuous use because they're not designed to filter switching noise sufficiently, all they need to do is charge.

 

I'd say your filter needs a tweak. I uased a DC-DC buck module in a power supply that I rebuilt which has some filtering but I could still see 150+mv of AC ripple on the 5v line under load, added an additional low ESR capacitor and a choke brought that noise down to around 30mv and cured the jailbar effect. 

Well it's one of those emi filter/choke from a microwave, I could add some ceramic caps and a zener or two to help regulate and further smooth the power, I've also noticed the lines are way worse on my usb2683 frame grabber, using the composite directly on the LCD I can't see really them (tv may also be removing noise and filtering the signal), but it's clear as day on the capture card, I haven't got any spare svideo plugs so I haven't used svideo though I think my lines are mainly bus interference and old components in the video mixing area, I think swapping c53 on mine should help fix it aswell

 

I've noticed these same lines on vcs hardware aswell

Edited May 28, 2020 by universal2600

[shoestring]

Don't you mean c50? Try a polymer solid electrolytic cap ( more reliable ) if you know c50 is bad. It's not rare for those to fail, just search the forum and you'll come up with some results.

 

But I think you'll get better results if you try a proper 5v power supply.