Macintosh Plus - Unknown CRT Problem

[HunterCupp]

Hello all

I have recently stumbled into my garage only to find a 28 year old Macintosh Plus, previously owned by my mother before me. After finding it, I was immediately scrambling throughout my garage looking for power cords, floppy disks, keyboard, mice, etc. Unfortunately, I had only found a power cord. (I am currently waiting for a Macintosh 128k/512k/Plus Etc Apple Branded Keyboard and mouse in shipping.)

My problem starts after I power on the Macintosh Plus. (I will include pictures)
I power on the Macintosh, followed by the 'Searching For OS' icon, there is a loud "beep". Everything seems to be working properly other than the fact the the display seems to be squished to a weird aspect ratio. For example, say that your current monitor has an aspect ratio of 16:9, it's just now been modified to 16:3. I am unaware why this would be, but I am almost certain it is CRT restricted. There is no shaking, waving, checker boards, lines, or any deformation of any kind on the display when powered or off, it's just the aspect ratio.

I hope that I will receive a reply soon, as I have a System 7.1 boot disk in the mail and am expecting it sometime early next week. I will spend the weekend checking in on this thread.

I have attached the pictures that I took for further detail...

P.S. The diagonal lines across the second picture are just from the camera, those aren't really there on the display.

-Hunter

 

[MacTech68]

Probably dry/cracked solder joints on the 4 pin yoke connector.

Depending on how long it's been running like that, the connectors themselves could be overheated and going brown. This makes them very brittle.

The original PCB mounted connector had very short pins that didn't protrude through the PCB very far, making this a fairly common issue. Apple much much later began to replace them on re-worked boards with connectors with longer pins.

One thing to try is to whack the case on the left side near the top edge. This may make the connection intermittently better, but ultimately, it needs to be re-worked.

There's a slim chance that it's the vertical height trimpot, but I doubt it.

 

[HunterCupp]

Thank you for replying, MacTech68.

I knocked on the top left edge a few times, fairly hard to try and knock the pins around as you instructed. There was no change, unfortunately. Also, to my knowledge, the display has been like this for the better part of 10 years, it was just like that one day. I am willing to try most of anything, but I have no major experience in soldering or any type of retro wiring. Would it be possible to see if the CRT cable connected to the PCB is loose? I'm sure that this Macintosh has taken its fair share of beatings in the past 28 years, things inside are bound to become loose. I am open to options.

-Hunter

 

[MacTech68]

The connectors itself clips on, so unless it's not been fitted correctly to begin with, it's unlikely to be loose, but not impossible.

If you've never soldered before, that may make it difficult, but who knows, you might have a natural knack for it.

You might be able to practice on some old junked boards first.

The first thing to do would be to get the case apart, and take a clear pic of the solder side of the analog board, that might prove one way or another what we're dealing with.

 

[HunterCupp]

Macintosh Plus Screwdriver

MacTech68

I understand that it's pretty late right now, so it will most likely have to wait until your morning, but as of this very moment I do not own the proper screwdriver to open the case. I will head down to my nearest department store and see if they have the one I need. If not, I can order one off of eBay, but of course it wouldn't get here until Tuesday most likely.

Just a quick thought just in case I need to prepare for the worst. Say that it's a problem with the connector on the PCB or something important like that. Would that specific thing be able to be replaced?

-Hunter

 

[HunterCupp]

Still Open for Help

I'm still open for options and ideas.

If anyone else has any other ideas about what could possibly be wrong until I get the screwdriver, I would be eternally grateful for your input.

-Hunter

 

[MacTech68]

Yes, it's late, but I'm a night owl (of sorts).

I think the PCB connector is a Molex 15-31-1046.

RS components should do this as 670-0286. But the above Molex part should be stocked by others too.

You may NOT need it as yet. I'm just looking at the worst case - a bad habit of mine (apparently).

 

[HunterCupp]

Funny thing, I bought a screwdriver for it, took it apart, and went to the soldering side you were talking about. There were two screws on that side. One label "Horizontal" and "Vertical" I messed with them a bit and this happened. It's not perfect, but it's an improvement. I can't seem to make them go any farther, so I'll assume they're maxed out. I'm not sure of what else I could do. I would have attached some pictures of the screws that I messed with, but I didn't think of it at the time and don't want to reopen it. (I had a hassle getting it closed again.)

-Hunter

 

[tdiaz]

A Capacitor could be at it's end and caused that to collapse. The adjusting pot being at the end of it's range is a good indicator.

I've had capacitors cause that issue before on other CRT setups.

Someone with one of the Larry Pina books can probably point at which it may be, though you can look at them and see if they're "puffy" on top.

--FAIR WARNING--

That nice red cable with the 'suction cup' on one end .. is very capable of giving you a rude awakening, and really should be discharged before you go poking around on that side of the board.

To discharge it, a flat screwdriver and a clip lead will work. Clip one end to the metal chassis, or somewhere that is grounded. Clip the other end to the metal screwdriver shaft.

Put your other hand in your pocket, grab your belt, or something.

With the machine face down for stability, push the flat blade under the suction cup and you may hear a "zzzzap/crack" noise.

Lift the cup a little and visually verify that you have made contact with the metal pins.

You can use the screwdriver to push one towards the center and lift, and pop that out.

While you have it off, clean off the CRT around the hole, and the bottom of the rubber with alcohol or similar, so when you put it back on, it's got a nice seal.

Look for puffy capacitors, and whatever else is browned, make notes.. on what may need replacing.

 

[MacTech68]

Hmmm. Well, it's difficult to pin-point any particular component. Many of the electrolytic caps in the vertical circuit are axial, and I have a hard time faulting them, but it's not impossible.

Looking at it, I'm curious that you say it just went like that one day and stayed that way. If that's how it happened, and there has been no vertical "jitter" since, then I'm suspecting a 6.2v zener AT CR15 (at least my first port of call and probably NOT the problem).

It's also apparent that the circuit relies heavily on several voltage rails, but the machine seems to work otherwise (does it successfully boot a floppy?), so I'm not leaning in that direction, but I wouldn't rule it out either.

As tdiaz says, sometimes you can be lucky and spot something that looks "cooked" and brown, or a capacitor that is severely bulging or leaking.

If you spot anything, take a picture and let's have a look. Even if you don't spot anything, a few good pics might allow old techs (referring to myself here) to spot something that doesn't look right.

I'm sure tdiaz and myself are happy to assist in any way we can - if you're willing to delve deeper. I certainly don't blame you if you're not.

EDIT: apparently, a dry/cracked solder joint on the J4 connector can cause this issue too. Resoldering the entire J4 connector is a good idea in itself.

 

[HunterCupp]

Tdiaz

I'm not too familiar with what would be considered "puffy". I will in face take several pictures of the inside for you and attach them to my next message. (I need to go find the screwdriver again.) I am aware of needing to discharge the CRT before I go about messing with everything, I found out the hard way. I felt a jolt as I was moving it around (CRT first) and I've been having mass amounts of static shock since.

-Hunter

 

[HunterCupp]

MacTech68

The more I think about it, the more I realize that I used the term "just like that" quite loosely. I mother had told me that, and I quoted. That being over 10 years ago, it was probably more complicated than that. I will however attach several pictures of everything I can in the next half hour or so. I did notice one thing that may stand out. The Vertical axis tuner was controlled by using a Flathead screwdriver in a screw and turning it counter-clockwise to make it larger, as the Horizontal tuner had no screw, but what seemed to be a small octogonal hole in which I could fit in the back of this long screw head I had handy. Turning it did nothing, but pushing and pulling the screw head in farther seemed to control it, very poorly however. Pushing the screw head in farther made the Horizontal axis retract (Get smaller) as pulling it slowly did the opposite. I would have assumed that they would have both had screws, but apparently not. This may or may not have been important, but I thought I should have mentioned it. As for the floppy disk, I will find out sometime early next week. I have an 800k System OS 7.1 Floppy Disk coming in through a website that sells their system startup disks.

There was also several more holes with odd ways of controlling them. One was a voltage control for something (Which I believe may be for the CRT?) but I don't remember without reading it again, I will check and attach a picture when I reopen the case. (Note that all of these "holes" were on the back side of the analog board.)

-Hunter

 

[HunterCupp]

MacTech68 and tdiaz

Here are the photos that you two requested. I have more if you need them, but 5 was the maximum amount of attachments I could use and putting them in a .zip file was too much memory (The max filesize it can be is 2.86 MB, mine was about 50 MB...)

-Hunter

 

[MacTech68]

Can't see anything untoward in those pics.

Your Analog Board is a few revisions in (which is a good thing).

However, If you want to proceed further, you'll need to remove the insulator card (the white card on the solder side of the circuit board.

Apple used two methods to attach these. The better of the two was "snap rivets", a re-usable, two piece fitting that went thru the holes in the card and corresponding blank holes in the circuit board. They are usually black. I've also seen single piece round thru-hole clips but these are harder to remove without removing the board from the chassis.

The other method was 3 1" squares of double-sided foam tape. This is the type you have. Unfortunately, once you pull the card off, tape squares aren't re-usable, although sometimes a small dot of superglue in the center of each square can do the trick or additional double-sided tape, but you need to retain the original foam squares to give you the clearance for the card to "stand off" the board.

WARNING: DO NOT put the rear case back on WITHOUT the white insulator card securely in place. The inside of the case is conductive (for the purpose of reducing RFI).

Also note - don't use a screwdriver or metal tool to adjust the "Width". For starters, you can crack the adjuster's core and the metal tool can interfere with how that component works.

If you feel you can proceed, we really need a good pic of the two locations circled in red below:

 

[HunterCupp]

MacTech68

Here is the photo of the soldering on the analog board as from your request.

-Hunter

 

[tdiaz]

That board actually looks quite good. The solder is all shiny, I don't see any browning, even the flyback solder looks good. Though it's quite possible it could be cold joints that are not visible in the flash/light. But it would usually have a dull look to it, when it's also cracked.

The most obvious tell-tale way of seeing a puffing capacitor is the "+" indent in the top isn't "grooved" anymore, and when it gets worse, they actually lift up and form a dome, and the bottom starts to pucker out. Those look great from that perspective.

OTOH, that's not an indicator that they're in good shape anyway, given the age range of ~25 years, and that you've had to turn the pot to the extreme to get what you have, and one could simply have failed enough to be out of spec, but otherwise be somewhat operable. On the digital side of things that would mean we're not going to work at all. But on the analog side, that's why there are pots. Because not everything is exact and needs to be adjusted periodically as tolerances change due to natural component breakdown.

..and.. yes, do -NOT- put that case back on without that insulating sheet. I've seen them where they've actually melted through the side of the case much like using a Light Saber to bust through a Death Star door.

Here's a component list as reference for values. I tried looking for the Larry Pina books here, and they're not readily accessible.

https://docs.google.com/spreadsheet/ccc?key=0AnmQLg8d1xThcE96S1Z0S3oxOUFiMkJEYy1nNzNuZEE&hl=en#gid=0

 

[MacTech68]

Here is the photo of the soldering on the analog board as from your request.

Ok, you'll need to clean the gum from the 4 pin yoke connector (uppermost) solder joints and re-solder them.

The row in the middle of the board also needs re-doing. Don't miss the right-most one, there is one pin omitted just before it.

You're lucky that it seems to be in the early stages. I've seen the yoke connector solder joints almost burnt to a crisp!

 

[tdiaz]

I'm not used to looking in photos for that, though I'd see it first hand, the photos make it look quite good, still.

 

[HunterCupp]

MacTech68 and tdiaz

So, basically MacTech68, you want me to re solder those two areas of solder to see if that fixes it as a first option yes? While as a secondary, tdiaz wants me to consider replacing the analog board all together? Seems fair enough. I'll get to that and solder everything sometime this coming week. I'll need to buy some soldering equipment.

I would suggest that you both keep checking in on this thread throughout the weekend just in case I decide to go out and buy some soldering equipment tomorrow. I'll keep you all updated on my decisions.

Also, MacTech68, could you outline the specific spots I need to solder again? I want to make sure that I don't solder something that doesn't need it. From what I can see, I solder the upper most area with 4 soldering spots and the area in the middle with 9 and the one to the right of the 9 within the red circle, yes? Also, how will I know if it works - the soldering? Will the screen just revert to normal? Or is the soldering just the start to a long process or technological work? (You can tell that I've never done this on an older Mac before.)

-Hunter

 

[tdiaz]

No, i'm not saying to replace it all together, as you're still going to have a ~25 year old board.

But I'd replace components based on the symptom showing, as a shot gun approach, if re-soldering those identified areas does not yield good results, because with it being in otherwise decent condition, the typical bad components are not jumping out and saying "HEY, I SUCK! swap me!".

I just don't have the book with a real schematic handy.

 

[MacTech68]

I'm not used to looking in photos for that, though I'd see it first hand, the photos make it look quite good, still.

Yes, I agree, but the lowest pin on the yoke connector does have a color change ring, which I saw so many times on those. Perhaps it's not the fault, but seeing that, I'd want to resolder them before delving deeper.

MacTech68 and tdiaz

So, basically MacTech68, you want me to re solder those two areas of solder to see if that fixes it as a first option yes?

Indeed, yes.

...could you outline the specific spots I need to solder again? I want to make sure that I don't solder something that doesn't need it. From what I can see, I solder the upper most area with 4 soldering spots and the area in the middle with 9 and the one to the right of the 9 within the red circle, yes? Also, how will I know if it works - the soldering? Will the screen just revert to normal? Or is the soldering just the start to a long process or technological work? (You can tell that I've never done this on an older Mac before).

New pic attached below: Quite correct. 4 of the yoke (arrows indicate) and the 9 within the circle and the one to the right (this is actually the "video" pin - famous for an intermittent blank screen). Might as well get all these done since they're so common and at least 3 of those 14 pins could cause your fault.

If it works, considering you've cranked the height to maximum, the screen will appear WAY TOO TALL. Adjust using the "Height" adjustment with a flat blade insulated screwdriver (IE, for your safety use a screwdriver with a plastic handle and only touch the handle). As a guide, adjust so that the black border is the same size all around - roughly.

Again, if you've never soldered, see if you can find a circuit board to practice on. You're looking to heat the join, by placing the tip of the iron against the pin & the circular pad simultaneously. When the solder flows, quickly add a small amount of new solder and remove the iron. The solder takes a second or two to solidify - don't move anything until it solidifies. You're looking for a shiny finish of a consistent texture.

You can use other tools to completely remove the old solder first which is sometimes preferred, but the above method should be sufficient for now.

 

[HereBeMonsters]

I would definitely recommend doing a little Maplin/Radioshack/Whatever hobbyist electronics store you have in your country soldering project before taking on something like that. I did a lot of this in Uni, but always do myself a little £5-10 refresher project before taking on something important (I mainly work on repairing audio equipment).

 

[HunterCupp]

MacTech68 and tdiaz

I see now. I'll get to work on that as soon as I can. In advance, I thank you all for your help. I should be posting again sometime this weekend or sometime early this week.

P.S. HereBeMonsters
I will definitely do that. I have a RadioShack close by and I'm sure that they'll be able to sort me out. I wouldn't want to screw it up because I'm new-ish into soldering. For things like this anyway.

-Hunter

 

[HunterCupp]

Ok, you'll need to clean the gum from the 4 pin yoke connector (uppermost) solder joints and re-solder them.

The row in the middle of the board also needs re-doing. Don't miss the right-most one, there is one pin omitted just before it.

You're lucky that it seems to be in the early stages. I've seen the yoke connector solder joints almost burnt to a crisp!

MacTech68

So, exactly how do I solder again? Re-soldering specifically. Do you just want me to heat up the solder that is there and leave it at that? Or somehow remove the solder that is there and apply new? I still have no soldering equipment but I am going to stop by RadioShack (My electronics store) tomorrow.

-Hunter

 

[MacTech68]

As I explained in my previous post, you can reheat the existing and apply a small amount of new solder to it, adding to what's there.

Or, with more experience, remove the old solder (either with a solder sucker or desoldering braid/wick). This method still may require adding some new solder to get it to flow sufficiently.

The problem with these connectors is the nylon plastic the pins are molded within. Too much heat for too long and they begin to soften and eventually melt. Hence, just re-heating and adding a little more solder should suffice - it's quicker.

When you add the new solder, just "jab" the end of the new solder strand at the location you are heating. Practice that way and you'll get the idea. The reason for the "jab" is to not add too much solder, which would form a huge blob.

I hope that makes sense.

HereBeMonsters' suggestion of getting a cheap kit to practice on is a very good one.