SE/30 - startup chime but no video

[dburr]

Attempting to refurb my SE/30, but am not seeing any video

- SE/30 logic + analog boards fully recapped
- I hear a startup chime, but don't see any video
- there IS neck glow
- in addition to recapping the analog board, I also tried replacing both of the ICs (SN74LS38N and TDA1170N), still no picture
- also reflowed all connectors on analog board
- probed video output pins on the logic board with my scope, and I do see a valid looking video signal
- furthermore, swapping in a borrowed analog board from an SE results in a good picture

I'm beginning to suspect that maybe the flyback transformer on my analog board is bad. But is there anything else I should check first?

 

[ScutBoy]

Attempting to refurb my SE/30, but am not seeing any video


- there IS neck glow

I was going to say make sure you plugged the neck board back in.

Don't ask me how I know that!

 

[PacificState]

It's not clear to me if the borrowed analog board includes a video board too - but if it does, check for dry joints on the original per my thread below.

 

[dburr]

It's not clear to me if the borrowed analog board includes a video board too - but if it does, check for dry joints on the original per my thread below.

By "video board" do you mean the board that connects to the neck of the CRT? If so, then no, I have not swapped the neck board, it is the one that originally came with the SE/30.

 

[PacificState]

OK:

- so the video/neck board *wasn't* swapped along with the analog board, and works with the loan board - thus ruling out the problem I had

- I presume you've twiddled the contrast control, too

Otherwise, I found the document at https://www.jagshouse.com/classicrepair.html which points to CR2/CR3/Q2 replacement. If not, you'd need a way to test the flyback which would bother me given the voltages - maybe there's a reasonable way to do it, though?

 

[dburr]

OK:

- so the video/neck board *wasn't* swapped along with the analog board, and works with the loan board - thus ruling out the problem I had

- I presume you've twiddled the contrast control, too

Otherwise, I found the document at https://www.jagshouse.com/classicrepair.html which points to CR2/CR3/Q2 replacement. If not, you'd need a way to test the flyback which would bother me given the voltages - maybe there's a reasonable way to do it, though?

Correct. Same video board, and yes I did try twiddling the various adjustments on the faulty analog board.
Thanks for the pointer, I'll check that out.

 

[craig1410]

I'm sure this is a silly question but have you tried adjusting the brightness control? I don't mean the various adjusters which are only accessible when the case is removed, I mean the control which is accessible from the front of the machine just underneath the CRT bezel.

 

[dburr]

I'm sure this is a silly question but have you tried adjusting the brightness control? I don't mean the various adjusters which are only accessible when the case is removed, I mean the control which is accessible from the front of the machine just underneath the CRT bezel.

DOh... thought I mentioned that in my original post, but apparently I was mistaken. yes I did try adjusting both brightness controls (both the one at the front of the computer, as well as the pot on the analog board). No effect.

 

[craig1410]

DOh... thought I mentioned that in my original post, but apparently I was mistaken. yes I did try adjusting both brightness controls (both the one at the front of the computer, as well as the pot on the analog board). No effect.

Haha, no worries. I hope you didn't mind me asking this but I've learned that it's often better to ask a silly question than not to. I kinda wish it was just the brightness, both for the entertainment value and the fact it's an easy fix!

I hope you find the cause - let us know if you do.