Minor (but annoying) CRT issue after SE PSU and AB Recap

[smrieck511]

Working on my SE FDHD.

Recaps went well. Tested voltages. Everything looked great. Put it back together.....

FORGOT TO CONNECT THE ANODE CAP!!! (Yes, Dumb, dumb, dumb...)

Anyhow, it ran for about 15 seconds before I realized the issue so I powered down and connected the anode cap.

The result is it works fine except I am have a very minor scan line coming down the CRT at a regular interval just like if you were recording it on a video but much, much less obvious. It does bug me enough to ask the question.

Have I taken out a component or worse, damaged the transformer by running it without the anode cap connected? Could this be caused by the recaps in some way. All the caps are the right specs.

Thanks for any guidance.

 

[Nixontheknight]

Working on my SE FDHD.

Recaps went well. Tested voltages. Everything looked great. Put it back together.....

FORGOT TO CONNECT THE ANODE CAP!!! (Yes, Dumb, dumb, dumb...)

Anyhow, it ran for about 15 seconds before I realized the issue so I powered down and connected the anode cap.

The result is it works fine except I am have a very minor scan line coming down the CRT at a regular interval just like if you were recording it on a video but much, much less obvious. It does bug me enough to ask the question.

Have I taken out a component or worse, damaged the transformer by running it without the anode cap connected? Could this be caused by the recaps in some way. All the caps are the right specs.

Thanks for any guidance.

I know this might not be the case for you, but I did that on a Macintosh Classic and killed the speaker, but depending on where the anode cap was, it could have damaged some components. if you have an in-circuit component tester, use that to see if the components are fine

 

[smrieck511]

Thanks, Yeah the anode cap was sitting on the outside of the CRT. Thankfully not touching anything else. I will check the components.

 

[ObeyDaleks]

Yikes. I made the same mistake before. Since then, I have a mental checklist that I perform every time I plug in a compact with the case off.

• Anode cap (I pull in it to make sure it’s secure)
• Neck board power
• Neck board ground
• PSU ground
• Deflection yoke power

It’s certainly possible that the cap fried some component depending on what it was resting on. But if it was just hanging in the air or up against the glass, I doubt it did any damage unless you actually saw some arcing.

Are you sure this symptom is not just placebo effect (trying to find something broken but it was already like that before). Imho very faint scan lines are not uncommon.

I would check the solder joints first - even ones you didn’t work on since you could have loosened things. I would also check the neck board since the joints can crack/separate from the pressure as you put it back on. Actually the neck board would be my first suspect.

 

[smrieck511]

Thanks. Yeah luckily just resting on the glass. No arcing. I'm gonna try the neck board from my SE/30 when I get home and see what I can deduce.

 

[s_pupp]

Thanks. Yeah luckily just resting on the glass. No arcing. I'm gonna try the neck board from my SE/30 when I get home and see what I can deduce.

What was the outcome? Did you find out what was causing the scan lines?

I did the same thing today, and now I get pale, slow moving scan lines that are quite distracting.

 

[smrieck511]

What was the outcome? Did you find out what was causing the scan lines?

I did the same thing today, and now I get pale, slow moving scan lines that are quite distracting.

yeah, I did fix it. It turned out after all of that that the ground wire in the power supply was poorly soldered or connected. I resoldered it, and everything was back to normal.

That power supply happened to be the Astec so I took out the three RIFA caps and that did not really have any effect on the power supply at all as far as I can tell. Works fine. (The Sony PSUs dont have RIFAs).

 

[zigzagjoe]

Both of my recapped SE/30 do the same thing. A faint scan line that takes maybe 2 seconds to move from top to bottom. Not sure if they did it beforehand, but it's not objectionable enough that I've done any other investigation.

 

[smrieck511]

as far as I can tell, those scanlines tend to be some kind of ground issue. In my case, the power supply.

but I wouldn't claim to know enough about it to be certain.

 

[Arbee]

A ground issue makes sense. The CRT itself acts as a filter capacitor for the high voltage, so good grounding all around is important.