Topic of the day: Superdrives and thier DONTs.

[techknight]

Learned a new lesson of the day: Dont plug in a superdrive pulled from an old LC575 series system into a mac 512k. It produces magic smoke and a dead chirping mac.

Why it done this, no idea, but i figured i would try it out since the 400k drive thats in there, isnt in too good of shape.

Lesson Learned.

 

[Mars478]

Woah thats not good.

But you should know that the 512k only supports up to 800k using an external drive! It's in the ROM! )

 

[techknight]

yea i realized that, but i figured the drive would still be electrically compatible. but nope.

 

[Mars478]

Well what symptoms does the 512k show? Maybe you can fix it!

 

[porter]

What component made the smoke?

 

[Mac128]

Why it done this, no idea, but i figured i would try it out since the 400k drive thats in there, isnt in too good of shape.

It had nothing to do with the Superdrive. They are electrically compatible. You have a bigger problem. A 400K drive CANNOT be used on a SWIM equipped Mac, but that's only because the PWM signal is not present to step the drive motor and is instead replaced by a 5V signal which can damage the 400K drive.

The Superdrive automatically senses the PWM input on pin 20 and defaults to 400/800K operation only. It requires a steady 5V signal to operate as a 1.44MB HD drive, which only a SWIM equipped Mac provides. I have used Superdrives on my stock 128K & 512K Macs without any difficulties.

The Superdrive draws more current than the 400K and the increased load probably was the last straw that pushed your borderline 512K over the edge.

 

[Mars478]

Ah! Then he did not do anything wrong! It probably was the Power Supply.

 

[porter]

Ah! Then he did not do anything wrong! It probably was the Power Supply.

You mean apart from exceeding the PSU load.

 

[coius]

Maybe he did, maybe he didn't. Most likely, if the machine was new and it had that draw on it when it was first built, I doubt it would have given up the ghost. I am betting the PSU was on it's last legs. I am wondering if it's a cap that busted or something...

I would check the Analog/power board and see if there is any charred remains. If possible, get a new PSU, or at failing that, try to fix the old one. It's possible, but have at it!

Let us know, JUST DON'T THROW OUT THAT 512K!!!!

 

[LCGuy]

I can confirm that auto-inject SuperDrives work fine on pre-SuperDrive Macs, having used an auto-inject SuperDrive on my 128k (with 512k of RAM and 512ke/Plus ROMs fitted). However, the LC575 uses a manual-inject SuperDrive, and even though in theory it should still work, I've never tried it myself, and quite frankly don't want to.

 

[techknight]

The problem with the unit, is the 400k drive rejects the disk, sometimes with a happy mac, sometimes without happy mac, rejecting disk, sometimes with an 0FXXXX sadmac code, sometimes it would boot all the way in, but that was very rare. I tried cleaning head and turning that adjustment screw, and redid the lithium grease where the mechanism is that handles the eject as it was malfunctining. nothin, i think the R/W alignment is out or the head is bad.

So i decided to stick a G3 style superdrive in there, my old and now destroyed 575 had the same drive, and i seen smoke from analog board, and then chirp-chirp-chirp from the analog board. I cannot find any charred remains of anything. yet....

Unplugged superdrive, machine fires up but still fails boot on the 400k drive, well tries to like before. The super drive causes power supply to whoop-whoop-whoop, so maybe shorted superdrive? it was one i had randomly laying around where i stripped a G3 beige years ago with an unstable logic board.

 

[Mac128]

smoke from analog board, and then chirp-chirp-chirp from the analog board.

Pina suggests checking the resistance across CR5. Anything higher than 3.6K Ohm may be a sign the flyback transformer needs to be replaced. It may also be the barrel rectifier at CR5. Is the floppy error code actually "XXXX" or random numbers? An 0F error code can be indicative of a poor voltage regulation, which it definitely seems you have. The first thing you should do before you do ANYTHING else is make sure all of your voltages are properly supplied.

Also, what is this Whoop-Whoop-Whoop sound? I can't say I've ever heard the power supply make such a noise. Is it a repetitive noise from the drive itself like constantly ejecting, or is it actually a musical sound from the PSU? Could you also describe it as "Flup, Flup, Flup"? CR21 on the PSU could be a culprit in that case.

I'm confused about which Superdrive you are using. Perhaps a model number? You say G3, but also 575. I have personally used a 575 Superdrive on my 128K.

 

[techknight]

smoke from analog board, and then chirp-chirp-chirp from the analog board.

Pina suggests checking the resistance across CR5. Anything higher than 3.6K Ohm may be a sign the flyback transformer needs to be replaced. It may also be the barrel rectifier at CR5. Is the floppy error code actually "XXXX" or random numbers? An 0F error code can be indicative of a poor voltage regulation, which it definitely seems you have. The first thing you should do before you do ANYTHING else is make sure all of your voltages are properly supplied.

Also, what is this Whoop-Whoop-Whoop sound? I can't say I've ever heard the power supply make such a noise. Is it a repetitive noise from the drive itself like constantly ejecting, or is it actually a musical sound from the PSU? Could you also describe it as "Flup, Flup, Flup"? CR21 on the PSU could be a culprit in that case.

I'm confused about which Superdrive you are using. Perhaps a model number? You say G3, but also 575. I have personally used a 575 Superdrive on my 128K.

depends on the differences of mine and your interpretation of whoop-whoop-whoop sound. Drive model JU-268A026C is what i used.

 

[Mac128]

depends on the differences of mine and your interpretation of whoop-whoop-whoop sound. Drive model JU-268A026C is what i used.

If you can record the sound it makes perhaps it may be relevant to someone here. Can you at least confirm if it comes from the drive itself, or definitely from some specific area of the PSU?

As for the drive, it is definitely NOT a stock 575. I presume now that you used the G3 drive in your 575 first?

According to this article, the JU-268A026C is a manual inject floppy manufactured by Panasonic which came stock in the first G3. It is definitely a Superdrive and is otherwise compatible with all earlier 400K disks, software and hardware. I keep coming back to Henry's claim that Apple switched to non-Superdrive 1.44MB drives (single speed PC drives) in late PPC & G3 Macs. However, this appears to be limited if at all. Perhaps, the Panasonic drives, while variable speed, were somehow electrically incompatible with a 512K. However, I find that highly unlikely considering it functions perfectly well on a 575 which is electrically compatible with earlier Macs. However, as the referenced article points out, the auto-inject floppies fail on the later OEM manual-inject systems. This suggests a likelihood that there is some minor difference that the extremely recent G3 floppy mechanism posses that could possibly cause a problem with your 512K Mac. Though to overload the PSU to such a degree seems to be an extremely unusual side-effect of an otherwise standardized interface. Surely such a recent drive has some electrical specifications online somewhere to compare.

One thing that comes to mind is that the Panasonic drive, being originally a PC manufactured drive, does not isolate pin 20 on the header to differentiate between the PWM and SWIM signal, i.e. it tries to interpret the PWM signal as the SWIM's +5V signal, resulting in a similar effect on an 800K drive, continually triggering the ejection mechanism. If that's the case, the ejection process is one of the highest loads the drive will put on the PSU, a continuous cycle will put a huge drain on the PSU and cause a weakened one to overload. One way to test this is to either brak the pin off the drive, or cut the associated wire on the ribbon cable (which at least allows you to repair it and return it to normal use).

But this really all comes back to you. Have you confirmed that your PSU is in good health and supplying proper voltages? Even under such a load, a healthy PSU, including a 128K/512K Mac's, would not react so violently to continuous ejection cycling. Putting non-standard equipment on a borderline Mac is just a recipe for disaster.

 

[tomlee59]

I'm fairly certain that "whoop-whoop-whoop" and "flup-flup-flup" or "whup-whup-whup" are all best efforts at describing the same thing: Power supply in self-protect mode. A current overload triggers it (an overvoltage will also indirectly trigger it), so anything that pulls too much current from the supply can make this happen.

 

[JDW]

After reading this entire thread, I would like to second Porter's excellent question that would put an end to all the speculation:

What component smoked?

I know the starter of this thread said that "smoke came from the analog board" and that he could not find any "charred remains." But if smoke was indeed seen coming off the analog board (with the case open, naked analog board in crystal clear view), then something on the analog board indeed caused it. And close examination of all the analog board components with a magnifying glass should reveal that. Brown and black burn marks should be visible on the source of that smoke.

Since your Mac is dead now anyway, you could just connect it back up again, and smoke it a little more to make it more visible.

Unless you find out what was burned, you will likely spend considerable time troubleshooting the board or considerable money swapping it out. Find the source of the smoke, replace the bad components, don't do it again.

 

[techknight]

Nope, with the superdrive removed, the mac fired back up. that made no sense to me.

 

[iMac600]

I'm fairly certain that "whoop-whoop-whoop" and "flup-flup-flup" or "whup-whup-whup" are all best efforts at describing the same thing: Power supply in self-protect mode. A current overload triggers it (an overvoltage will also indirectly trigger it), so anything that pulls too much current from the supply can make this happen.

Spot on. The power supply goes into self-protect mode, where it constantly attempts to seemingly restart the power flow. The "whoop" or "flup" sound (both of these sounds are correct) is the floppy disk drive attempting to start up, being cut short, attempting to start again and so forth, all in time with the power supply starting and restarting. If the FDD is disconnected, in this case the machine powered up just fine, but on machines with deeper issues you'll only hear the PSU whistling in time with where the "flup" noise would normally occur.

It's caused by one of three things, unfortunately all three are pretty broad headings and require some narrowing down to determine the direct source of the issue.

• 1. Something is pulling too much power from the electrical feed. This could be any component except the analog board drawing too much current, such as another component with an internal short.
   
  2. The power supply can not keep up with the demands of the attached components. This often occurs when the power supply is worn and needs replacement components, mostly capacitors.
   
  3. There is a problem routing power around the power supply. Think of a cracked solder joint on a flyback transformer for example, the electricity can not pass through a broken joint and therefore the power is not reaching its destination. The power supply goes into self-protect mode as a result.

It sounds like 1 or 2 are the most likely in your case, but it requires some knowledge of the superdrive to narrow it down. Additionally knowing which component let out the smoke would also be a handy hint. I can only deal with issues 2 and 3 for the most part, but everyone here already has it covered.

 

[Mac128]

Nope, with the superdrive removed, the mac fired back up. that made no sense to me.

This makes perfect sense if the Superdrive is pulling more power than the 400K drive.

Also, I have seen an analogue board smoke before without killing the Mac. In fact, I have seen an analogue board smoke without finding any obvious scorching or burn marks. However, one thing is certain. If your analogue board is out of adjustment enough to cause smoke, then you have yourself a ticking time bomb and it is only a matter of time until merely flipping the power switch with only the stock hardware blows it up.

You have far bigger problems right now than whether the floppy drive works. And the Superdrive had nothing to do with it. Your Mac's analogue board is on its last legs and in dire need of repair. The longer you wait the worse the cascade of damage.