ghost lines

[jimhmphry]

I was reading about ghost lines in a post the other day and i to have those type of lines. is this some thing that can be fixed or should i just put up with them. i know i know ask 133 he knows all but am i the only one with these. ive looked but didnt see how to fix this in the other post talking about this subject just thought it was worth of it own post.

[133MHz]

Are you talking about faint vertical lines in the Famicom's video output, like jail bars?
That's an AC adapter problem (dried up main filter capacitor). Replace main filter capacitor or entire AC adapter.

[jimhmphry]

yes very faint lines do you have a pick or could you tell me were this is?

[133MHz]

Inside the AC adapter. It's the only component inside that looks like this (sorry for the big pic):


Replace it with a larger value capacitor if possible.

Caution! Filter capacitors have polarity. The stripe running on the side of it indicates the negative lead.
Please take note of the orientation of the capacitor on the board. If you reverse the capacitor, it will explode!

[Steev]

Just because Im interested, what does that capacitor? 

[jimhmphry]

tried a power plug that came with a tg 16 i got awile back its values are dc9v-850ma +)---c---(- the same resolts

[133MHz]

Just because Im interested, what does that capacitor? 

It's time for some basic AC adapter theory:

The AC adapter in your Famicom takes the 120V AC of the wall outlet and transforms them into 10V DC.
To do this conversion, it needs three key components:

Transformer: Just a simple iron transformer. It provides galvanic isolation and reduces the 120V AC of the wall outlet into 10 V AC. Famicom doesn't want AC, it wants DC, so we need to turn that AC into DC.

This is how AC looks like (AC stands for Alternating Current, you can see why - polarity is reversing constantly):


And this is DC (Direct Current, like from a battery, constant all the time):


Bridge rectifier (Rectification): Four diodes in a special arrangement that turns AC into pulsing DC. Basically it blocks the negative parts of the AC cycle and turns them into positive ones.This is almost DC, the polarity doesn't reverse but the current isn't constant.

Filter capacitor (Smoothing): This is just a big electrolytic capacitor. Capacitors are energy storage devices, like batteries but they can release all their energy in a short time. The pulsing DC charges this capacitor, and when the current falls, the capacitor discharges, this repeated charging and discharging keeps the current at a constant level. Finally we have DC!

Here's a schematic diagram:


The 'Regulation' part is inside of the Famicom, the rest is inside the AC adapter.

When the main filter capacitor dries up, it can't "smooth" the pulsing DC correctly anymore, this means that the DC output starts pulsing a little (which is known as ripple), and that pulsing on the normally constant power produces vertical bars in the image and buzz in the audio.

[jimhmphry]

i dont have buzz noise and the lines are so light it does not really matter just thought it might have a simple solution.

[133MHz]

It is a simple solution, replace a capacitor and that's it .
Your TG-16 adapter could be marginal too, remember that these things are more than a decade old by now, and the electrolyte on the caps dries up.

[Ichinisan]

I can confirm that a bad power supply can cause buzzing audio.

I don't have a Famicom, just a USA NES. I've had buzzing audio and couldn't figure out what was wrong. I had been using a universal power adapter with selectable voltage / polarity...and I never trusted it.

Finally, I went to a local game shop. They were selling "compatible" adapters that listed several different compatible systems. I wanted an original NES AC adapter. The NES adapter (unlike the Famicom) outputs AC and all "compatible" plugs output DC. They had one original in the back of the store and the brick was held together with tape. They even gave me $1 off.

It totally fixed the buzzing audio.

Since the USA NES has the rectifier built-in, the filtering capacitor should also be built in. So maybe the "filter" in the universal power supply had a bad capacitor and it and couldn't provide enough juice to the filter capacitor inside the NES...? (I don't know what I'm talking about)

[Xious]

I have to say, the 'faint lines' problem stems from multiple sources, so this isn't an absolute solution.There is a lot of discussion on this topic all over the forum, so you might want to search for 'jail bars' , ' vertical lines', etc. I personally find tat they are blatantly obvious on newer TVs, but older (1980s) sets show nothing; the same is true of A/V mods. I never see the lines on a C1702 or Magnavox monitor, but if I use a 25" TV, they are clear with my AN-500.

I eventually plan to do a run of A/V conversion kits (pre-made, ready to apply) and will ensure that there is no possibility of having the lines when doing so, even if that means over-complicating the design. As a side-note, if you want a nice, new PSU, I have them for sale for $12.95.

[petik1]

Im not sure about the famicom, but i do know that on the sega game gear, ghost lines were caused by a bad cap on the main board, but as said above, it could be multiple problems.