Hello all, good day,
TL;DR : In sum, I'm trying to resolve a dead HDD in an otherwise promising Mac SE FDHD. What follows is a description, some ideas, and a question about the 53C80.
--
A neighbor found her husband's old SE FDHD in the attic and I offered to check it out. It is a late model (RAM jumper, socketed battery). Inside, I found a dead but unexploded battery and what I believe is a 3rd-party HDD expansion. So, it has two 1.44 floppies and a stealth Quantum ProDrive 40 S sitting above them. I added more SIMMs, put in a new battery, and it booted 6.0.3 from a diskette. Video is good, sound works, both floppies are reading and booting 1.44 diskettes, ADB works. Have not tested the serial ports or external floppy. Finder shows 4,096KB RAM.
The Quantum has an APN sticker that reads 940-40-9401, a foil sticker that reads "40 S".. so I presume it is a "real" Apple HDD. It does lack the red-ink Apple logo sticker, if that matters. It has its termination resistors in their sockets.
I blew out the dust throughout the system, looked for any debris between pins, and used a dry cotton swab to really de-dust the fan. The fan is fairly quiet, so I have not rebuilt or replaced it.
The HDD, however, is not recognized. I hear it spinning very quietly and smoothly, and only the barest hint of heads moving (which might just be old bearings rattling periodically - it is very quiet, more or less periodic, and infrequent). If I attach an LED to its activity indicator, it blinks once during startup, then comes on and stays on. Disk Tools for System 6.0.3 does not find it. The internal ribbon cable has a small amount of wear and I have not yet done a continuity/short check on it.
So, theory 1: Perhaps the HDD is so old that it's taking too much current to spin up? I have no means to test this, I think. I have tested the power connector in-circuit and the HDD is getting a solid supply on the 5V and 12V pins.
I have a Zip 100 SCSI and its branded DB-25 connector cable. Placing this on the external connector also does not result in it being found. This is not the best experiment, as I do not know if I have a bootable, 7.5.5-or-earlier Zip disk with the Zip extension on it. I last used this Zip SCSI in the post 7.6.1 days.
So, theory 2: bad SCSI cable, perhaps shorts from insulation lost during installation or re-opening. Digikey has replacements for $25 each so, holding off on that.
So, theory 3: Dead 53C80. This is a bit of a leap with the small amount of information I have so far, plus I don't know what other parts could fail and result in this symptom.
I have removed the Quantum and its cable and my next test will be to try a different disk. I don't have a replacement internal cable, but I'll examine the existing one better, first. I'm waiting on the replacement disk now.
I will also try recognizing the Zip drive with the Quantum and its cable removed. I think I can create a Zip drive from an image using an ATAPI Zip250 I have on a Windows box. I just need to find an image with the Zip extensions.
Finally, just in case I cannot rule out the 53C80... I am in search of pinouts for the old 40-pin DIP Zilog 53C80 or a schematic of the SE. I have found and ordered the modern replacement for it from Zilog, but it is now a 44-pin PLCC. I believe this is the very PLCC used on the SE/30, and I'm willing to make a DIP adapter to retrofit it into my SE if I can determine which pins are which on the DIP40 packaging. I have limited reworking skills but may be able to get the old one out without lifting a pad -- but I will be lucky if I do.
So, question: I'm still searching this site, I'm sure it's here -- but if anyone can point me at an SE schematic or relevant 53C80 data sheet, my thanks in advance.
Thanks for reading this. I hope I have done the right amout of experimentation before posting, and described the issue well.
TL;DR : In sum, I'm trying to resolve a dead HDD in an otherwise promising Mac SE FDHD. What follows is a description, some ideas, and a question about the 53C80.
--
A neighbor found her husband's old SE FDHD in the attic and I offered to check it out. It is a late model (RAM jumper, socketed battery). Inside, I found a dead but unexploded battery and what I believe is a 3rd-party HDD expansion. So, it has two 1.44 floppies and a stealth Quantum ProDrive 40 S sitting above them. I added more SIMMs, put in a new battery, and it booted 6.0.3 from a diskette. Video is good, sound works, both floppies are reading and booting 1.44 diskettes, ADB works. Have not tested the serial ports or external floppy. Finder shows 4,096KB RAM.
The Quantum has an APN sticker that reads 940-40-9401, a foil sticker that reads "40 S".. so I presume it is a "real" Apple HDD. It does lack the red-ink Apple logo sticker, if that matters. It has its termination resistors in their sockets.
I blew out the dust throughout the system, looked for any debris between pins, and used a dry cotton swab to really de-dust the fan. The fan is fairly quiet, so I have not rebuilt or replaced it.
The HDD, however, is not recognized. I hear it spinning very quietly and smoothly, and only the barest hint of heads moving (which might just be old bearings rattling periodically - it is very quiet, more or less periodic, and infrequent). If I attach an LED to its activity indicator, it blinks once during startup, then comes on and stays on. Disk Tools for System 6.0.3 does not find it. The internal ribbon cable has a small amount of wear and I have not yet done a continuity/short check on it.
So, theory 1: Perhaps the HDD is so old that it's taking too much current to spin up? I have no means to test this, I think. I have tested the power connector in-circuit and the HDD is getting a solid supply on the 5V and 12V pins.
I have a Zip 100 SCSI and its branded DB-25 connector cable. Placing this on the external connector also does not result in it being found. This is not the best experiment, as I do not know if I have a bootable, 7.5.5-or-earlier Zip disk with the Zip extension on it. I last used this Zip SCSI in the post 7.6.1 days.
So, theory 2: bad SCSI cable, perhaps shorts from insulation lost during installation or re-opening. Digikey has replacements for $25 each so, holding off on that.
So, theory 3: Dead 53C80. This is a bit of a leap with the small amount of information I have so far, plus I don't know what other parts could fail and result in this symptom.
I have removed the Quantum and its cable and my next test will be to try a different disk. I don't have a replacement internal cable, but I'll examine the existing one better, first. I'm waiting on the replacement disk now.
I will also try recognizing the Zip drive with the Quantum and its cable removed. I think I can create a Zip drive from an image using an ATAPI Zip250 I have on a Windows box. I just need to find an image with the Zip extensions.
Finally, just in case I cannot rule out the 53C80... I am in search of pinouts for the old 40-pin DIP Zilog 53C80 or a schematic of the SE. I have found and ordered the modern replacement for it from Zilog, but it is now a 44-pin PLCC. I believe this is the very PLCC used on the SE/30, and I'm willing to make a DIP adapter to retrofit it into my SE if I can determine which pins are which on the DIP40 packaging. I have limited reworking skills but may be able to get the old one out without lifting a pad -- but I will be lucky if I do.
So, question: I'm still searching this site, I'm sure it's here -- but if anyone can point me at an SE schematic or relevant 53C80 data sheet, my thanks in advance.
Thanks for reading this. I hope I have done the right amout of experimentation before posting, and described the issue well.