Recapped SE/30 with No Video

[MeTheMac]

Hi,
I got a recapped Macintosh SE/30 and the motherboard needed some work so I sent it off to u/AmigaOfRochester to get it all fixed up -- great guy, he did fantastic work on the SE/30 motherboard and my Mac Portable motherboard, highly reccommend! At the time of purchase the machine powered on and went to the desktop but had a few issues, like no sound.

However, I just got it back and plugged everything in and for some reason the CRT doesn't seem to be outputting any video! I've tried changing the wheel on the front of the Macintosh and the Cut Off pot but no luck.

The board on the back of the CRT is plugged in and I have reflowed the Analog board connectors. I don't see any light or anything in the glass at the back of the tube when powered on if that is important. The Fan does spin up.

Thank you!

(repost from r/VintageApple Reddit post)

 

[vtgearhead]

I can't tell from the available diagrams, but some video displays powered the CRT filament from a winding on the flyback transformer. If that's the case with the SE/30 then missing H-Sync from the motherboard would result in the symptoms you describe.

 

[MeTheMac]

@vtgearhead What would that mean? How could I fix it?

 

[vtgearhead]

It could mean just about anything (motherboard, cabling, something on the analog board), but first step is to find out if heater voltage in the SE/30 is tapped off the flyback. I took a quick glance at the available diagrams and it's really not clear how the heater is powered.

 

[MeTheMac]

Hmm, okay. Sorry for my inexperience but how would I test the heater voltage? Tysm for the help!

 

[vtgearhead]

Please don't take this the wrong way, but if your bench skills are limited it's much healthier (in the physical sense) to not poke around in the display electronics. Beside the second anode lead from the flyback to the tube, there are high voltages on the analog PCB.

 

[MeTheMac]

Totally understand. I'm pretty new to CRTs but I'd really like to try to fix this if possible.

 

[JDW]

@MeTheMac
You did not mention if you hear a bong when you power on. You only said the screen is dark. A bong would be a sign of life.

Next, because Amiga of Rochester did the repair, it would be good to ask him his advice in light of your current symptoms. Do that just to make sure he didn't overlook something during his repair.

Next, I suggest you start with page 147 in Larry Pina's Dead Mac Scrolls book to see what symptoms may match what he describes there:

The Dead Mac Scrolls 1992 : Free Download, Borrow, and Streaming : Internet Archive

The Dead Mac Scrolls 1992

archive.org

 

[MeTheMac]

Haha, completely forgot. Yes, chime is present. I have reached out to Amiga of Rochester and we are led to believe their is something wrong with my CRT or Analog board of the system, but not sure where to continue from there.

 

[JDW]

It's at times like this that having more than one model of the same Mac is very handy. If you only had another SE/30 or SE, you could put your motherboard in that other machine and test it. If all is well, then you could do an Analog board swap. If all is well, then you could know if indeed the CRT is bad (however unlikely that is).

 

[MeTheMac]

Haha, yeah. I'm getting an LCD and new PSU soon so hopefully I can install that, just trying to eliminate as many issues before I install it, but I guess we'll see!

 

[robin-fo]

Haha, yeah. I'm getting an LCD and new PSU soon so hopefully I can install that, just trying to eliminate as many issues before I install it, but I guess we'll see!

Your analog board is certainly repairable; if you decide to part with it and the CRT, please consider offering it for sale here!

 

[MeTheMac]

I definitely will be!

 

[djc6]

I like using a device like this to easily see if there is HSYNC or VSYNC signal at the J12 connector (I don't own this):

SE-COMBO (IDC12) - Joe's Computer Museum

The SE-COMBO brings together features of two of our best sellers; the Universal TTL Video Adapter and the ATX Breakout Adapter.

jcm-1.com

There is also a similar device that outputs VGA - bypassing the analog board: https://jcm-1.com/product/se-combo-macpicovid-edition/

You can also power SE/30 off ATX power supply for bench testing just the logic board.

Here is a thread with more info and videos showing how to use these devices: https://tinkerdifferent.com/threads...uality-video-output-on-your-compact-mac.3890/

I don't own either of the above devices, they didn't exist at the time I bought more expensive device from CayMac vintage that outputs HDMI instead of VGA:

https://ko-fi.com/s/e600bd3867

This has been super helpful for bench testing my SE/30 and connecting a much larger LCD to the system. But I'm intrigued by the much cheaper options from Ron's Computer Videos.

I had recapped an SE/30, it ran for a few hours great - and then no video. Chip "UG8" failed which prevented both HSYNC and VSYNC from being generated. It had been damaged by leaking electrolyte. The system would give a happy chime on startup.

 

[Elemenoh]

At the time of purchase the machine powered on and went to the desktop but had a few issues, like no sound.

It could be a lot of things, but it seems like a decent possibility something didn't get put back together correctly or was damaged on take-apart/reassembly.

I'm sure you did already but can you confirm the video cable coming from the analog board was plugged into the logic board?

Also, you mentioned turning the brightness pot. Maybe check the solder joints on there. If you smushed it when putting the thing back together you might have knocked a joint loose.

The board on the back of the CRT is plugged in and I have reflowed the Analog board connectors.

Which specific joints did you reflow? Can you take a picture and mark up which ones?

 

[MeTheMac]

Okay, so I installed the LCD. However, it chimes and then quickly gives a sad mac tone. Nothing ever shows on the screen. Interestingly, when I remove the 30Video card driving the LCD it does not give the sad mac tone. I tried installing the Accelerator and no error. Then tried plugging the 30Video card onto the Accelerator, and it errored again! Any ideas? @JDW, you seem to know a lot about this haha.

 

[JDW]

Okay, so I installed the LCD. However, it chimes and then quickly gives a sad mac tone. Nothing ever shows on the screen. Interestingly, when I remove the 30Video card driving the LCD it does not give the sad mac tone. I tried installing the Accelerator and no error. Then tried plugging the 30Video card onto the Accelerator, and it errored again! Any ideas? @JDW, you seem to know a lot about this haha.

Because you mention having a 30Video card, I will tag its creator, @zigzagjoe , to gather his thoughts.

You mention having obtained an LCD too, but you seem to have the stock analog board, so I assume you do not have the full LCD kit from ZigZag?

https://68kmla.org/bb/index.php?threads/fs-se-30-color-lcd-kits-16-bit-30video-hc.48970/

I do not own the 30Video card or the LCD kit, although I am seriously pondering that kit. The only experience I have which can help is basically what I said before. When I have SE/30 troubles, I can move components piece-by-piece to another working SE/30 machine to verify which part works and which does not. In other words, if I have a known good SE/30 rig, I can pull its analog board and put a "suspected bad" analog board into the rig and if all is well, then I know the root problem isn't the Analog board.

Measuring voltages at the external floppy connector on the motherboard is also important, and while that can be done with a multimeter, paper clips and GREAT CARE, a Mac-O-Meter is faster and safer (and yes, I have one):

https://ko-fi.com/s/5593914468

But testing machines in their stock condition is an important, because if it doesn't work in the stock condition, it probably won't when upgraded to things like 30Video.

But again, I will defer to ZigZagJoe and his thoughts, since you are using his card in your machine right now.

 

[MeTheMac]

Makes sense :/
Yeah, I've talked with ZigZagJoe and I'll send him back the cards just to make sure that it isn't an issue with the cards. Thanks for all the help!

 

[zigzagjoe]

Yep. There is a question of if it's the LB or the card, while I function & burn-in test each card for an hour or two during QC there's always the possibility something has gone wrong. So, it's time to eliminate variables.

 

[MeTheMac]

Agreed, I'll send the cards over tomorrow. Anyone else have thoughts on diagnosing the logic board? I'll take some photos and add them here in just a second.