Is my flyback transformer dead?

[Gsbtom]

My old college era MacPlus (orignally a 512 but upgraded to a MacPlus) has had blank screen since the 90's. Finally pulled it out of the closet when I was junking a bunch of stuff and figured I'd give it a shot. Re-soldered J4 and J1, and bingo, I've got a screen. The old ProAPP 20S HD works too and boots. Spent an hour or so of playing around with it, turned it off and went to dinner. Sadly, when I went to boot up the Mac later tonight, I have what looks like a classic flyback issue. I was seeing some wavy lines on the edges prior to this, and was preparing to resolder the flyback, but now I've got this (with a burning electronics smell):

Everything on the board looks ok, no obvious signs of burning or anything. This is the flyback, hard to tell if it's bad:

I haven't replaced any caps on the board at this stage (they all look to be ok).

 

[Gsbtom]

Bump.... any ideas what this CRT issue is?

 

[AwkwardPotato]

The glue on that flyback looks pretty burnt, so I wouldn't be surprised if it's bad. The Dead Mac Scrolls also suggests that the flyback and/or horizontal output transistor are dead. Also, just because the caps look good doesn't necessarily mean they are good.

 

[Gsbtom]

Thanks, I didn't know about the Dead Mac Scrolls PDF (I have Pina's other book), that's a super helpful book.

Fair point on the caps, I'll likely recap this board, but need to source a flyback transformer first, which searching for so far seems difficult. Only one I've found is https://www.ebay.com/itm/157-026C-Flyback-157026C-Replaces-Apple-HR-42031/121655780759?hash=item1c533fe597:g:CNUAAOxy14VRWxL3:rk:2f:1&frcectupt=true which seems pricey as heck (or simply buying an old Plus or SE which would cost more).

Anyone have any other ideas on sources for a flyback? I've read that you can (and should) replace with a 157-0042C but I can't find those at all.

 

[trag]

It's unfortunate, but at some point Dalbani realized there was a market for those things.  They used to sell the 0042C for $5 on their website, about ten years ago or so.   Their prices steadily crept up through the twenty-teens.   I didn't realize it had gotten that high.  I think Artmix sells a new manufacture version on Ebay, but I don't remember what his pricing is like.

 

[LaPorta]

If I come across an analog board that I won’t be using, I’d definitely sell the used flyback to you for a heck of a lot less than that.

 

[Gsbtom]

Looks like Artmix hasn't sold anything on eBay anyway for over a year.

If I come across an analog board that I won’t be using, I’d definitely sell the used flyback to you for a heck of a lot less than that.

Let me know. I don't mind spending the $$$ but obviously would prefer to spend less...

 

[Gsbtom]

So an update: I ordered a replacement flyback from Dalbani (grrr $$$), a replacement for Q3 (found a BU406D at arcadeshop), and a set of replacement caps.

Pulled the old flyback. Two different angles from it, can't see any obvious burning, or tell if it's really fried or not.

Pulled and replaced Q3 with a BU406D. I'm suspecting that Q3 may have been the true culprit here, as the plastic broke apart when I gently tried to pry it off the heat sink. The heat sink (not pictured), was slightly discolored, but not severely.

Unfortunately, I pulled up a trace on this. Note to self, fully read Pina, I'd forgotten that I needed to twist the heat sink's holder tabs to get the heat sink off. This patch I put in is really not my best work. I'm a novice solderer here.

Installed the new flyback. The new one from Dalbani is labelled (incorrectly I'm guessing) as "157-026-C". It does fit, however, into the same outer ring of holes that 157-0026-B was in.

Power on test, success!

I was able to adjust the vertical centering, but unfortunately, the screw in the horizontal pot appears to be missing, and the pot itself looks torn up inside.  No idea if I did that years ago or if it was done during a previous repair years ago. It's not perfect, but good enough.

Put it all back together, and booted the hard drive. Crystal Quest was probably my favorite game back in the day.

Introducing my son to retro Macintosh games.

Lastly, hooked up the FloppyEmu board, and backed up the hard drive. It's very old and I don't trust it to last forever, plus the FloppyEmu came with a bunch of neat software to play with (including some games I don't have).

Things still to do:

1. Install 4MB of memory, well, because. On order.
   
2. Clean slight corrosion from battery older and install new PRAM battery. On order.
   
3. Left shift key is still wonky. I pulled it apart last week and found a total hack job on the board underneath, but oddly enough not on any trace connected the affected shift key. I resoldered the shift key pins and it now sort of works. Needs more investigation.
   
4. Pull the floppy and give it a good cleaning. It does read the one floppy disk I have (that was left in it for 30 years). Looks like the last time I used this was when I was using it to help test Netware network stuff in the early 90's, as the disk is a Netware Macintosh Developer's Kit Disk 1 of 2. Go figure.
   
5. Recap the analog board.
   

 

[Johnnya101]

Wow, looks like a nice and bright CRT! Good job.

Theres a guy who sells Plus and earlier style keyswitches on ebay, pretty cheap too if ya need some. I have a couple extras too.

 

[LaPorta]

Excellent work. Sometimes you have to come up with those crazy patches.

 

[trag]

The last time I ordered from Dalbani, they had an assortment of BU-406D transistors on their website (not on Ebay).   So you might have been able to get them all at one source.   Nice job on the repair. 

 

[Gsbtom]

Thanks all!

I'll look into the key switch if I can't get it to work reliably. For the most part it's fine, I'm going to try a little WD40 in it to see if that clears it up for good. For reference, this is what I found on the keyboard logic board.

Not my handywork! This makes me wonder where I got this keyboard from. As this was originally a 512, I would have had the original smaller keyboard (which I no longer have, or at least haven't seen it in years, along with the original power and SCSI cables that came with it). I'm wondering if I "liberated" this from my school's junk pile or something, or bought it used from the shop when I did the upgrade.

On the floppy repair, it does read disks, but won't eject them (paperclip ejecting works fine). I'm guessing a good head cleaning and lubrication is in order. What's the best thing to use to lubricate? I'll also check the eject gears too.

 

[Johnnya101]

Use alcohol or similar to clean grease, use white lithium to lube. Put a dab on the motor rails and such too.

 

[Gsbtom]

excellent, thanks. Sounds like next weekend's project.

 

[Alexlfm]

Is the floppy the 400k or 800k since I know you said this was an upgrade? This is a big difference. I take the 400k drives apart, take the mechanism completely off and then soak it in WD-40. For the 800k drives it becomes quite a bit trickier to get all those pieces off and cleaned. You really have to completely disassemble the drive to do it, so if a drive works mostly, but stick sometimes, I just leave it. I still try to get everything off that I can (mainly the top) and then soak as much as possible in WD-40 while actuating all of the mechanism. Nothing else will penetrate enough to clean the joints. White Lithium works well once it's been cleaned and for the rails and stepper, but not with getting it unstuck. I'd be guessing it's a gearing issue if it's not ejecting at all. In my experience it should eject partially if it's a lubrication problem. I do have a spare eject motor should you need one.

 

[Alexlfm]

Also your keyboard is off a plus. The standard 512 didn't come with the numeric keys and I don't know if they even sold the keyboard then as one unit (the num pad was available separately). That was standard with the plus.

 

[Gsbtom]

Looks like it's an 800k drive, judging by the size of the one floppy I have (779k formatted according to Finder). And it's ejecting now, albeit it seems like it's straining a bit, so looks like I might be able to clean it up and get it fully working without much effort. So looks like the eject motor's ok. Might be an issue with the gears, but won't know until I inspect it more closely. Given that the 512 would only have had a 400k by default, I'm wondering if I got the 800k drive during the Plus upgrade...

On the keyboard, yeah, I definitely got this after the fact. When I originally got the Mac, I got a nice case for it, which had space for the computer, the original keyboard, mouse and external floppy. The Plus keyboard sticks out the top (so you can't quite zipper it closed) as the case wasn't made for it obviously, heh. I do remember the external numerical keyboards, pretty sure the Mac's in the school's computer lab had them, though pretty sure I never did. I may have had an external floppy, though that's probably long lost.

Other fun stuff: I found a folder labelled CS231 folder on the hard drive, with Turbo Pascal and Lightspeed Pascal, and a bunch of Pascal school projects still there. It's been 30+ years since I've written any Pascal code, though (all C#/Java these days), so it's kind of neat looking at 19 year old me attempting to code.

 

[Dog Cow]

Also your keyboard is off a plus. The standard 512 didn't come with the numeric keys and I don't know if they even sold the keyboard then as one unit (the num pad was available separately). That was standard with the plus.

The M0110A keyboard with numeric keypad and arrow keys could be purchased separately. It cost $129 in 1986. The Macintosh Plus Keyboard Kit (P/N M2519).

Is the floppy the 400k or 800k since I know you said this was an upgrade? 

This photo shows that it is an 800K drive:

 

[Gsbtom]

Oh interesting, didn’t realize you could tell visually like that.