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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Can anyone point me to documentation or schematics for this?
I have one in pristine condition, until last month when a capacitor blew... Turns out these use the problematic Astec power supplies identical to the ones used in the Osborne 01. There is a 0.1uF 250V polymer cap that tends to blow. In fact, I've had 2 Osborne 01 machines that blew while in service. I replaced the cap and now they work perfectly. The Westwind, on the other hand, will not recognize the hard disk. However the built-in ramdisk does work. My fear is that when the cap blew, a voltage transient may have taken out one or more of the large Shugart VLSI chips on the disk controller board. These chips may be difficult to source these days. -John |
#2
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In article ews.com,
John Crane wrote: Turns out these use the problematic Astec power supplies identical to the ones used in the Osborne 01. There is a 0.1uF 250V polymer cap that tends to blow. Is it a RIFA Yellow/clear/foil looking thing, wired across Live/Neutral as part of the incoming filtration? If so, these infest other stuff, like ICL One Per Desk PSUs, Apple II+ PSUs, SYMBFile 5.25" external harddrive enclosures etc. and they fail with a crackle, hiss, bang and smoke. In each case, removing the charred remains stops the smoke and allows the device to work just fine. Replacing them with appropriate modern caps is possible too, but not essential to operation. https://eevblog.com/forum/chat/old-r...isaster-story/ The Westwind, on the other hand, will not recognize the hard disk. However the built-in ramdisk does work. Did the power cut out suddenly when the capacitor went (blown fuse?), or did you power off in a panic? Could unexpected loss of power have upset an "old" hard drive (no time to head park?) -- --------------------------------------+------------------------------------ Mike Brown: mjb[-at-]signal11.org.uk | http://www.signal11.org.uk |
#3
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On 5/18/21 2:05 PM, Mike wrote:
In article ews.com, John Crane wrote: Turns out these use the problematic Astec power supplies identical to the ones used in the Osborne 01. There is a 0.1uF 250V polymer cap that tends to blow. Is it a RIFA Yellow/clear/foil looking thing, wired across Live/Neutral as part of the incoming filtration? Exactly! It is a RIFA. If so, these infest other stuff, like ICL One Per Desk PSUs, Apple II+ PSUs, SYMBFile 5.25" external harddrive enclosures etc. and they fail with a crackle, hiss, bang and smoke. In each case, removing the charred remains stops the smoke and allows the device to work just fine. Replacing them with appropriate modern caps is possible too, but not essential to operation. https://eevblog.com/forum/chat/old-r...isaster-story/ The Westwind, on the other hand, will not recognize the hard disk. However the built-in ramdisk does work. Did the power cut out suddenly when the capacitor went (blown fuse?), or did you power off in a panic? Could unexpected loss of power have upset an "old" hard drive (no time to head park?) That's an excellent point. As soon as I saw the smoke, I hit the power switch. I may have just lost the data and need to reformat. Of course, I don't see any utilities to do that. So more exploration is needed. -John |
#4
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#5
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In article ,
Rayner Lucas wrote: with a thick plume of absolutely foul clinging smoke. I must have got the alternate-flavour ones, somewhere between burnt toast and toffee. Although 100% unwanted when coming out of a piece of electronic equipment, it's not *that* bad. ![]() If the hard drive is an old shoe-box style one (5.25", full height) that uses stepper motors to trundle the head out over the disk and back, then they don't tend to like having the head dropped on the active disk -- any sign of diagnostic LEDs on the drive, as these can start giving blink-codes to say "Didn't spin up, there's a head holding me back!" etc. -- --------------------------------------+------------------------------------ Mike Brown: mjb[-at-]signal11.org.uk | http://www.signal11.org.uk |
#6
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#7
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#8
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![]() On 2021/05/19 6:21 a.m., Mike wrote: In article , Rayner Lucas wrote: with a thick plume of absolutely foul clinging smoke. I must have got the alternate-flavour ones, somewhere between burnt toast and toffee. Although 100% unwanted when coming out of a piece of electronic equipment, it's not *that* bad. ![]() If the hard drive is an old shoe-box style one (5.25", full height) that uses stepper motors to trundle the head out over the disk and back, then they don't tend to like having the head dropped on the active disk -- any sign of diagnostic LEDs on the drive, as these can start giving blink-codes to say "Didn't spin up, there's a head holding me back!" etc. Might need a "Shake & Bake" operation to get it spinning again...I used to pick up the drive and hold it in my hand, then quickly rotate my wrist in the direction of spin to free up the heads. Then back up the disk right away! John :-#)# |
#9
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On Wed, 19 May 2021 12:19:25 -0700, John Robertson
wrote: snip Might need a "Shake & Bake" operation to get it spinning again...I used to pick up the drive and hold it in my hand, then quickly rotate my wrist in the direction of spin to free up the heads. Then back up the disk right away! I had to do similar with a genuine IBM PC that I'd added a FH (5MB) ST506 interfaced HDD to that wouldn't always spin up from power-on (I used it to run the Co BBS (TBBS) and it was typically on 27/7). I would hit the power switch then sharply twist the whole PC around about 45 Deg and back (as you say, on the same plane as the platters) and it always span up. ;-) Cheers, T i m |
#10
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On 5/19/21 1:48 PM, Mike Coon wrote:
In article , SPAMPLEASE says... I was remembering a lingering phenolic reek that took hours to dissipate even with the windows open, but that was from the Schaffner power inlet incident so the scorched potting gunk may well have contributed that particular fragrance :-) For an evil smell I can recommend a failed selenium rectifier from my youth. IIRC like over-cooked school cabbage. I think I might have its successor in the EHT of my homemade oscilloscope... Well.. this RIFA smelled like Texas BBQ. Not too bad actually.... -John |
#11
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On 5/19/21 3:24 PM, T i m wrote:
On Wed, 19 May 2021 12:19:25 -0700, John Robertson wrote: snip Might need a "Shake & Bake" operation to get it spinning again...I used to pick up the drive and hold it in my hand, then quickly rotate my wrist in the direction of spin to free up the heads. Then back up the disk right away! I had to do similar with a genuine IBM PC that I'd added a FH (5MB) ST506 interfaced HDD to that wouldn't always spin up from power-on (I used it to run the Co BBS (TBBS) and it was typically on 27/7). I would hit the power switch then sharply twist the whole PC around about 45 Deg and back (as you say, on the same plane as the platters) and it always span up. ;-) Cheers, T i m Definitely something to try. I'll give it a shot. -John |
#12
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On 5/19/2021 3:24 PM, T i m wrote:
On Wed, 19 May 2021 12:19:25 -0700, John Robertson wrote: (I used it to run the Co BBS (TBBS) and it was typically on 27/7). Another TBBS alumni! I ran The Golddust Plantation back when. RwP |
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