What kind of fix is this?

[SlowCoder]

Got a nice Sears Heavy. It works, but the display is dark.

 

Anyway, I opened it up, and this is what I found:

Due to the fact there are what look like service tags taped to the mainboard, I'm guessing this is an Atari service repair. But I'm looking at the quality of the work and wondering ...

What is the large square thing on there? A resistor from the 1800's?

 

I opened another Heavy and here is apparently what it should be:

I think I will install new parts.

 

Input is invited.

[SlowCoder]

Update: I found out the dark image was due to a bad RF cable. Replaced, and video is great.

 

Back to the "mod" on this board. I removed it to see what it does. After I removed it, I could see no change in the operation of the Atari.

 

Technical details:

GND > 4.7uf cap > chicklet looking item (resistor?) > CPU pin 24

 

The chicklet looking item is marked ORG ORG BRN, which, if a resistor, would lead me to think it's a 330ohm. But when I tried to measure it with my meter, 0.

 

Would love an explanation.

[zylon]

I've seen that, but never had to mess with it. I'll look into it later.

[mtshark7]

It seems they might have been trying to do the cleaner picture modification where you attach 680 Ohm or two 330 ohm resistors in series across pin 6 & 9 on the TIA chip.

[Pioneer4x4]

is that some type of choke?

[SlowCoder]

It seems they might have been trying to do the cleaner picture modification where you attach 680 Ohm or two 330 ohm resistors in series across pin 6 & 9 on the TIA chip.

 

Pretty sure that's not it. It's connected from GND to CPU pin 24.

[Benzman66]

Mark,

One thing you may want to try to make the screen lighter is to adjust the video modulator a bit. Use a hex tool or alignment tool if you have one. If you look on the bottom of the little silver box, you will see a hole. Stick the tool up and turn it to the right a little until the picture brightens/sharpens up. Many time if a new or different RF cable is put on, they don't make the adjustments, and that can leave the picture darker and more "blurred".

 

DON'T try to adjust from the top hole.

[SlowCoder]

DON'T try to adjust from the top hole.

Ooh! Ooh! What does that do? I'm guessing it fine-tunes the frequency?

[Benzman66]

DON'T try to adjust from the top hole.

Ooh! Ooh! What does that do? I'm guessing it fine-tunes the frequency?

 

She says it's too big for the top, much easier to go from the bottom. Something to grab onto.

Yep, it fine tunes things.