Classic II cure not so curative - a mininovel with photos :P

[MidnightCommando]

Hi there.

Meet my Macintosh Classic II.

It has been behaving rather badly lately, displaying a checkerboard pattern on the internal CRT whenever I fire it up. At this rate, the most useful thing from this Liberation might have been the single solitary HyperCard diskette that was in its superdrive!

Here is a picture of the infamy it displayed. :simasimac:

A little internet research revealed that the problem was a well-known fault due to the SMT electrolytic caps deciding they were ready to die spectacularly.

So, what course of action should I take, other than to bust out my labcoat and soldering iron, and attempt a recap of the board!

That's all and very well when you have the knowledge to pull it off - I didn't. This was my first repair job that actually required extensive resoldering, and I was only "fairly sure" my replacement caps were actually still working.

I gathered up a list of capacitors that were needed and found them in my junk box:

• C3 47µF, 16V
  
• C4 47µF, 16V
  
• C5 10µF, 16V
  
• C6 10µF, 16V
  
• C7 10µF, 16V
  
• C8 10µF, 16V
  
• C9 1µF, 50V
  
• C10 10µF, 16V
  
• C11 10µF, 16V
  
• C12 10µF, 16V
  
• C13 47µF, 16V
  
• C14 10µF, 16V
  
• C15 1µF, 50V

Unfortunately, It appears I have made things significantly worse with my attempt. xx( xx( xx( xx( xx(

Here are some photos of the board :

The caps near the sound hardware that tend to leak most obviously, from what I've read, replaced with electrolytics of equal value.

The caps near the RS422 controllers and near the RAM - I don't know what they do exactly but I replaced them anyway, because they were leaking also.

The fully reassembled logic board, after being very carefully cleaned, reseating the ROMs and the RAM SIMMs ...

The problem I now face is that on switching on the Classic II, I hear the fan spin up, and nothing else. No chime, and furthermore, I don't see ANYTHING on the CRT where once there was a nice ready-made chess board

Has anyone here any ideas what this particular failure mode likely means? If higher-res photos of the board are needed, I can do that easily. I'd just like my Classic II working.

I'm going to be getting some new SMT caps at some point, in case my caps are just bad, but i've no idea how to solder SMDs so that might be a bit pointless. Also, if I screwed something up while soldering I'd like to know before I spend $20 on a set of replacement caps ( yes, they're that expensive here for tants! - I might have to see if trag will ship me some and how much it would cost... )

So, I ask you all, any ideas?

 

[Unknown_K]

Double check your work (make sure the + and - of the capacitors is in the correct spot). The video needs the 1uf 50V capacitors to work. No bong means either the capacitor on the sound circuit is messed up, or you might not have the RAM correct in the socket.

 

[MacJunky]

Double check your work (make sure the + and - of the capacitors is in the correct spot). The video needs the 1uf 50V capacitors to work. No bong means either the capacitor on the sound circuit is messed up, or you might not have the RAM correct in the socket.

The board has the positive side marked. They look correct from what I can see on the markings on the PCB. But that soldering job .. I am not going there.

 

[MidnightCommando]

But that soldering job .. I am not going there.

Please do go there. It's rubbish, I know that. I was actually wondering if cold solder joints (it was very difficult to work on that board with my iron) could possibly be to blame.

 

[MidnightCommando]

Ok... an update.

I decided the solder joints probably didn't take due to me not cleaning the pads after desoldering, and hence them possibly having electrolyte still on them.

This was borne out when i desoldered all the replaced caps and found many sticky points, so I'm now going to wash those areas.

In the process of desoldering, I accidentally ripped out the positive pad on capacitor C8 (10µF, 16V) - I'm sure I don't need to explain why I feel really bad about that.

Can anyone here tell me where it connects? Or, advise me of a way to safely get the trace reconnected to the cap?

 

[MidnightCommando]

get the trace reconnected to the cap

Ok... another update.

I've scraped off the solder mask over that via that leads to C8 very delicately, and tried to solder a wire to it. bad idea - the wire wouldn't stay in place as the solder was heating up . Long story short, I ripped out the top of the via connected to C8 + by accident. Can anyone tell me where it leads, so I can manually connect it please?

EDITI've now also lost C4's negative lead... is there any hope?

 

[Mars478]

Seems like you've nuked the classic II as I have.

I can sell you my classic 2 Lobo if you want. I think it has leaky caps, but it's stock. The Analog board on mine is nuked.

 

[Mars478]

Also, I'd like to say, your Avatar is the absolute coolest thing I have ever seen. Source?

 

[MidnightCommando]

Also, I'd like to say, your Avatar is the absolute coolest thing I have ever seen. Source?

some person on deviantArt who did it. it's a 512*512 png - I personally converted it to a finder icon

Classic II Lobo

Other than that you're in NY, that sounds pretty cool ... maybe I'd screw that one up less. I should really buy some recaps off trag. the electros I used can't have done much good.

How much would you want to sell said logicboard for? (Note, I can't guarantee this will happen, because of varying factors the most of which is "my parent needs to approve everything" but I would love to buy the board from you.)

 

[Mars478]

It's light I guess.

BUT I do not know if it works or not, no guarantee.

 

[Osgeld]

for future reference, to solder onto small items, such as pcb traces, clean off the mask, tin (that is apply a tiny amount of solder) to the pad, tin the wire THEN just melt the 2 together, also dont use big fat wire on tiny traces, use something like a single strand of a floppy disk cable, or wirewrap wire

 

[Trash80toHP_Mini]

get the trace reconnected to the cap

Ok... another update.

I've scraped off the solder mask over that via that leads to C8 very delicately, and tried to solder a wire to it. bad idea - the wire wouldn't stay in place as the solder was heating up . Long story short, I ripped out the top of the via connected to C8 + by accident. Can anyone tell me where it leads, so I can manually connect it please?

EDITI've now also lost C4's negative lead... is there any hope?

Those are through-hole leads and vias, correct? :?:

If so, you've soldered the wrong side, pre-SMT boards of that vintage were "Wave Soldered" and any connection in a through-hole doesn't actually need the top pad unless there's a surface trace connected to it. In that case, repair the damage with a rework patch (those little pieces of wire commonly found on old boards, either coupled with an intentionally cut trace to remedy faulty PCB Design, to complete a circuit that was accidentally left out of the PCB design, or a "naturally occurring" faulty trace connection on an otherwise perfectly serviceable PCB) and be done with it.

BTW, from the context of your posts, it seems to me that you're describing traces, not vias. IIRC, a via is a through-hole with no component lead soldered through it. A via's purpose is to make interconnects for traces on different layers, either top to bottom on a "two sided board" or anywhere on the layers between on a "Multi-Layer PCB" like your Classic II's.

Check for HiRes scans of your board in the NuBus Mafia collection over at Applefritter, there may be all the reference you need to fix your board there. If not, you can certainly find the end points of the trace with a continuity tester.

 

[Trash80toHP_Mini]

get the trace reconnected to the cap

Ok... another update.

I've scraped off the solder mask over that via that leads to C8 very delicately, and tried to solder a wire to it. bad idea - the wire wouldn't stay in place as the solder was heating up . Long story short, I ripped out the top of the via connected to C8 + by accident. Can anyone tell me where it leads, so I can manually connect it please?

EDITI've now also lost C4's negative lead... is there any hope?

Those are through-hole leads and vias, correct? :?:

If so, you've soldered the wrong side, pre-SMT boards, and hybrid boards like yours, of that vintage were "Wave Soldered" and any connection in a through-hole doesn't actually need the top pad unless there's a surface trace connected to it. In that case, repair the damage with a rework patch (those little pieces of wire commonly found on old boards, either coupled with an intentionally cut trace to remedy faulty PCB Design, to complete a circuit that was accidentally left out of the PCB design, or a "naturally occurring" faulty trace connection on an otherwise perfectly serviceable PCB) and be done with it.

BTW, from the context of your posts, it seems to me that you're describing traces, not vias. IIRC, a via is a through-hole with no component lead soldered through it. A via's purpose is to make interconnects for traces on different layers, either top to bottom on a "two sided board" or anywhere on the layers between on a "Multi-Layer PCB" like your Classic II's.

Check for HiRes scans of your board in the NuBus Mafia collection over at Applefritter, there may be all the reference you need to fix your board there. If not, you can certainly find the end points of the trace with a continuity tester.

 

[MidnightCommando]

BTW, from the context of your posts, it seems to me that you're describing traces, not vias. IIRC, a via is a through-hole with no component lead soldered through it. A via's purpose is to make interconnects for traces on different layers, either top to bottom on a "two sided board" or anywhere on the layers between on a "Multi-Layer PCB" like your Classic II's.

I do know what a via is. I'm saying, I accidentally ripped off the top of one that the trace from the cap lead went to - i now have NOTHING to solder to. the ... I think the word is "annulus" of the via is GONE. Mars' assessment that I am up a certain creek without a certain propulsion device is almost certainly correct - I screwed myself

A rework patch implies that I can actually solder to something. I can't. There is nothing to solder to - the solder won't take to what's left of the via (which is, in this case, not a through-hole - it is a blind via) ... and in fact the solder wasn't taking to ANYTHING.

(I apologise for being defensive, but I'm kinda bummed at how epicly I've failed here.)

Check for HiRes scans of your board in the NuBus Mafia collection over at Applefritter, there may be all the reference you need to fix your board there. If not, you can certainly find the end points of the trace with a continuity tester.

I doubt my continuity tester will tell me much. But, the hires scans sound good, I'll have a look. Thanks.

 

[MidnightCommando]

It's light I guess. BUT I do not know if it works or not, no guarantee.

suggest a price ... seriously, I don't have money out the ears but I am looking to get this machine working. If your board doesn't work I'll just strip the analogue board down to parts and keep the CRT as a spare for my Mac 128k once I figure out how to get it repaired.

( p.s. could you possibly throw in the saucer-with-slot shaped mic that comes with the classic II, if you have it? :\ )

 

[Osgeld]

I doubt my continuity tester will tell me much

nah, you could just practically reverse engineer the entire machine with a continuity tester, it wont be much help

also back the heat off your iron, it seems to be way too hot if your loosing pads like crazy and the solder wont stick to anything but, and use plenty of flux

 

[Trash80toHP_Mini]

I do know what a via is. I'm saying, I accidentally ripped off the top of one that the trace from the cap lead went to - i now have NOTHING to solder to. the ... I think the word is "annulus" of the via is GONE. Mars' assessment that I am up a certain creek without a certain propulsion device is almost certainly correct - I screwed myself
A rework patch implies that I can actually solder to something. I can't. There is nothing to solder to - the solder won't take to what's left of the via (which is, in this case, not a through-hole - it is a blind via) ... and in fact the solder wasn't taking to ANYTHING.

(I apologise for being defensive, but I'm kinda bummed at how epicly I've failed here.)

NoPro, comrade, I understand, been there, done that and I've got the burn scars to prove it, but the ex got the T-Shirt in the settlement. :-/

BTW, the only stupid question, here in the 68kMLA, is the one that doesn't get asked!

Whatever . . . how about creating a "new annulus" (albeit a "solid" one) by using just the right gauge wire to almost fill the hole, providing a path for the solder to connect to the buried layer, sort of the way a plumber "sweats" a copper pipe <-> fitting connection?

Check for HiRes scans of your board in the NuBus Mafia collection over at Applefritter, there may be all the reference you need to fix your board there. If not, you can certainly find the end points of the trace with a continuity tester.

I doubt my continuity tester will tell me much. But, the hires scans sound good, I'll have a look. Thanks.

De nada, comrade!

I love your avatar too, but the designer missed the boat, IMHO. If the colors were a tad brighter, solid, and ordered correctly to match the Rainbow Apple Logo, it'd be absolutely PERFECT!

 

[Mars478]

The saucer that sticks to the classic on the side? I don't have that... The soonest I could get it to you is this weekend. Hey someone here name a price for what you think the Lobo is worth, I have no idea.

 

[MidnightCommando]

I do know what a via is. I'm saying, I accidentally ripped off the top of one that the trace from the cap lead went to - i now have NOTHING to solder to. the ... I think the word is "annulus" of the via is GONE. Mars' assessment that I am up a certain creek without a certain propulsion device is almost certainly correct - I screwed myself

BTW, the only stupid question, here in the 68kMLA, is the one that doesn't get asked!

As with many civilised places on the tubes, I'm led to believe.

Whatever . . . how about creating a "new annulus" (albeit a "solid" one) by using just the right gauge wire to almost fill the hole, providing a path for the solder to connect to the buried layer, sort of the way a plumber "sweats" a copper pipe <-> fitting connection?

Way ahead of you, and in many ways behind. I attempted this already. As I said, the solder won't take to the board. I know it's not a problem with my technique as I assembled a multimeter a few days ago without incident.

De nada, comrade!

I love your avatar too, but the designer missed the boat, IMHO. If the colors were a tad brighter, solid, and ordered correctly to match the Rainbow Apple Logo, it'd be absolutely PERFECT!

I agree. I'd do it myself, but frankly I'm not a graphic designer. I'm a photographer and a sucker for old tech.

However, the Rainbow Apple colours would be totally pimpin'.