Ziggystar12 Posted April 27, 2017 Report Share Posted April 27, 2017 Best thread ever! Quote Link to post Share on other sites
Ziggystar12 Posted April 27, 2017 Report Share Posted April 27, 2017 Two follow up questions. What is the situation when your floppy drive won't boot and runs slow? I've seen two boards doing that now. Scsi boots fine. Machine is happy Mac otherwise. Internal and external floppy ports suffer the same. Even a floppyemu won't work. Is there an ic to blame? What does the 16-18 pin 1k resistor trick do, when should I use it? Quote Link to post Share on other sites
Mc128k Posted April 27, 2017 Author Report Share Posted April 27, 2017 Two follow up questions. What is the situation when your floppy drive won't boot and runs slow? I've seen two boards doing that now. Scsi boots fine. Machine is happy Mac otherwise. Internal and external floppy ports suffer the same. Even a floppyemu won't work. Is there an ic to blame? What does the 16-18 pin 1k resistor trick do, when should I use it? About the floppy I would start a new thread, as this isn't related to power regulation. I haven't investigated on it, but if you follow the first scheme I posted you should be able to check if there is power first. 16-18 as you can read from techknight's posts is a hack that kickstarts the IC chip into oscillating. As this is a power-saving IC, it compares the values periodically, and not in a continuous mode. Sometimes it gets stuck it seems, and this trick gets it back to checking the input values. Check out the datasheet if you need more info. Quote Link to post Share on other sites
Mc128k Posted April 27, 2017 Author Report Share Posted April 27, 2017 Another thing, just to update the topic. The lead-acid cells have arrived and I reassembled the battery pack. It just works perfectly, so absolutely no IC/FET/Transistor was harmed during my awful experiments. So... it is done now. Everything in full working order, just like new. I also see that using the bench power supply the computer actually asks for more than 1.5A, so a limiting power brick is mandatory in every case. Like somebody wiser said.. do not use the gray brick. Ever. Quote Link to post Share on other sites
Ziggystar12 Posted April 27, 2017 Report Share Posted April 27, 2017 (edited) Forgot to mention, if you boot to scsi it works but I get the Mac will shut down in 10 seconds message with a full battery and plugged in. So maybe still related to power regulation? Do you solder the resistor or just touch temporarily? Edited April 27, 2017 by Ziggystar12 Quote Link to post Share on other sites
Mc128k Posted April 27, 2017 Author Report Share Posted April 27, 2017 Can you post some details on your workbench setup? How are you powering the mac? What voltage exactly? Using the original wires? The portable is a bitch with power control and regulation, most problems can be hunted down to incorrect usage I think. Quote Link to post Share on other sites
techknight Posted April 27, 2017 Report Share Posted April 27, 2017 As far as the floppy drive, the SWIM IC is a known failure point in the Portable. You can find an old SE/30 board or a IIsi board or something that got battery acid exploded, you can pull and swap the SWIM ICs. That should fix it. Quote Link to post Share on other sites
Ziggystar12 Posted April 27, 2017 Report Share Posted April 27, 2017 Theoretically if one inserted a ram card while the 9v backup battery was active, (big pack removed but battery lid open) would that blow out this swim ic? Quote Link to post Share on other sites
techknight Posted April 28, 2017 Report Share Posted April 28, 2017 (edited) it shouldnt. But I do know that on those machines, if 1 of the 2 red wires loses voltage, it can fry the SWIM, I have witnessed it first hand. what it does it cause the 5.2V to lose regulation, and will show AC adapter voltage at 7.5 to 7.8VDC, and the SWIM gets hit first. And to be honest, after following a couple threads, the wiring harnesses are starting to become problematic, Whether its the microswitch or whatnot. The microswitch if I recall is double-throw. Meaning there are 3 wires that go to it. If the microswitch gets bad to the point to where the normally closed position is open as well as normally open, it CAN cause the 1-wire only voltage situation which frys the SWIM and causes a shitload of other regulation problems. Edited April 28, 2017 by techknight Quote Link to post Share on other sites
Ziggystar12 Posted April 29, 2017 Report Share Posted April 29, 2017 So why not tie the two red wires together either in the bundle or on the motherboard? I thought one Input was for the 9v battery only and the other for the large battery? Does using only the large battery with no 9v fry things? Quote Link to post Share on other sites
Mc128k Posted April 29, 2017 Author Report Share Posted April 29, 2017 (edited) No, the wires are soldered together at the microswitch, any failure of the switch shouldn't impact this, the cables remain shorted. They both give 6.5V from the lead acid battery OR the 9V battery when flipping the switch. The 9V voltage is dropped by two diodes on the wire. Edited April 29, 2017 by Mc128k Quote Link to post Share on other sites
techknight Posted April 29, 2017 Report Share Posted April 29, 2017 (edited) Then there have been changes over the years, because mine are not wired like that. Only 1 of the wires switches over to 9V from 6V while the other one is hot 6V all the time unless you remove the battery. Edited April 29, 2017 by techknight Quote Link to post Share on other sites
Mc128k Posted April 29, 2017 Author Report Share Posted April 29, 2017 Weird, I thought I had the first version. As you can see here, the two wires on the right are soldered together and they go directly to the board. I presume that if you had them separated there could be issues when the main battery was connected without a backup battery (the frying you were talking about), so they had them joined while keeping a hot wire and a smaller one. Just a thought. This is the rebuilt cable, as before both wires are soldered at the switch. Quote Link to post Share on other sites
Ziggystar12 Posted April 29, 2017 Report Share Posted April 29, 2017 What diodes did you add to drop the voltage of the 9v? My wire had the diode a while back but the diode burned out and I didn't replace it. I thought it was just a protection diode. Quote Link to post Share on other sites
Mc128k Posted April 29, 2017 Author Report Share Posted April 29, 2017 I did not add diodes, they were pre-built in the cable, an official "Apple Hack". They are for both protection and voltage dropping, I can't remember their type, but any rectifier I think will do fine, they don't need special features. They were the black type, not the glass ones. Quote Link to post Share on other sites
Raoul Posted January 13 Report Share Posted January 13 (edited) Hi I found your topic searching for "Macintosh portable Q16". I've opened my Portable for the first time yesterday, because I wanted to recap it after some years in my attic. One of the last time I used it, many years ago, I have tried to install the Com card, and instantly I've got a burn smell. Shut the Portable off, removed the card, booted it again, and it was still working. So today I've checked the card : light corrosion near the ports, one capacitor seems leaky, and Q16 seems fried. So I've some questions, and here seem one of the best places to get an answer I don't want to do more damages. • Do you think after recap I can boot it securely without changing Q16 ? • Do you have the reference for Q16 ? • I'm not an expert, and not used to such heatsinks, what's the best protocol to remove Q16 ? I thank for any answer. Raoul Edited January 13 by Raoul typo Quote Link to post Share on other sites
techknight Posted January 13 Report Share Posted January 13 Doesnt look fried to me. Just blackening on the heatsink plating from corrosion. Thats it. Quote Link to post Share on other sites
Raoul Posted January 13 Report Share Posted January 13 For my Q16, it's not corrosion, but overheating. Reading again the full topic, I'm wandering if the culprit was not the Com card, but me (I don't remember exactly, it was a very long time ago) using a grey power supply in place of the white one. Quote Link to post Share on other sites
glay78 Posted January 14 Report Share Posted January 14 What’s the symptom of a failed Q16? Quote Link to post Share on other sites
techknight Posted January 14 Report Share Posted January 14 (edited) 19 hours ago, Raoul said: For my Q16, it's not corrosion, but overheating. Reading again the full topic, I'm wandering if the culprit was not the Com card, but me (I don't remember exactly, it was a very long time ago) using a grey power supply in place of the white one. No it isnt. I was replying to your post. Your Q16 heatsink is blackened from tarnish/corrosion. Not heat. That is not to say that the transistor got hot over the years, but the blackening of the heatsink is due to tarnishing. Edited January 14 by techknight Quote Link to post Share on other sites
techknight Posted January 14 Report Share Posted January 14 4 hours ago, glay78 said: What’s the symptom of a failed Q16? Dead machine. its the 5.2V regulator. Quote Link to post Share on other sites
glay78 Posted January 14 Report Share Posted January 14 2 hours ago, techknight said: Dead machine. its the 5.2V regulator. ok great thanks! Quote Link to post Share on other sites
techknight Posted January 14 Report Share Posted January 14 (edited) 2 hours ago, glay78 said: ok great thanks! If it shorts, it'll send 6V to 7.5V to all the 5V chips which would fry everything up stream, basically bricking the board. I have seen it. its rare though. The first thing it takes out is the SWIM, and a handful of 74 series logic next to the CPU. Edited January 14 by techknight Quote Link to post Share on other sites
glay78 Posted January 14 Report Share Posted January 14 2 hours ago, techknight said: If it shorts, it'll send 6V to 7.5V to all the 5V chips which would fry everything up stream, basically bricking the board. I have seen it. its rare though. because sometimes after I run my portable from start to sleep cycle and a few times within an hour or so , it will register as low batt even the batt is fully charged. It will then go to sleep to prevent batt from draining. I’m not too sure what’s causing it. Quote Link to post Share on other sites
techknight Posted January 14 Report Share Posted January 14 (edited) 2 hours ago, glay78 said: because sometimes after I run my portable from start to sleep cycle and a few times within an hour or so , it will register as low batt even the batt is fully charged. It will then go to sleep to prevent batt from draining. I’m not too sure what’s causing it. Thats a bad PMGR/Hybrid. Very common, and short of that, could be caps/resistors support components in the circuitry between them. Edited January 14 by techknight Quote Link to post Share on other sites
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