[cctalk] Re: Qume 842 8" Disk Drive Question
The drive works perfectly for double sided disks (using the appropriate index hole). Yea, 8" drives are a bit funny like that. You know this, because context. Some future google-ologist might not. So. 8" drives have a different index position for SS and DS. In your case I suspect either the emitter LED or the receiver phototransistor ro maybe the wiring or what ever conditioning on the PCB is b0rken for the SS sensor. Assuming of course your drive has two sensors -- I have not yet owned an 8" drive like that, the ones I have had were dedicated SS or DS. W
[cctalk] Re: Qume 842 8" Disk Drive Question
I haven't worked on 8" drives since the early 80's with th exception of the RX02 drives on my PDP-8. And DEC worked their own "magic" on those drives :) Thanks for the help. On 1/31/2024 3:59 PM, Chuck Guzis via cctalk wrote: On 1/31/24 13:03, Mike Katz via cctalk wrote: Michael, Thank you, that was what I was planning as my next step. I haven't checked to see if the service manual has a full schematic. The main purpose of my message on here was to see if I was missing something obvious like an option trace cut or something like that that I missed when I checked the manual. Thanks again, Mike - There is indeed a schematic in the 842 service manual PDF page 87 is what you're looking for. Since the LEDs are always powered, you need only be concerned with the output of the phototransistor. DMM is fine; no scope necessary. An opto going bad is not completely unknown on these drives. (I have a couple of the 842s--good drives, otherwise) Diskette drives really are non-intelligent devices... --Chuck
[cctalk] Re: Qume 842 8" Disk Drive Question
I believe the pull ups are all on inputs from the external controller and not for outputs from the drive itself. Looking at the schematic the Index output (J1-P20) does not go through the pull up resistors. Thanks again for your help. On 1/31/2024 3:59 PM, Chuck Guzis via cctalk wrote: On 1/31/24 13:03, Mike Katz via cctalk wrote: Michael, Thank you, that was what I was planning as my next step. I haven't checked to see if the service manual has a full schematic. The main purpose of my message on here was to see if I was missing something obvious like an option trace cut or something like that that I missed when I checked the manual. Thanks again, Mike - There is indeed a schematic in the 842 service manual PDF page 87 is what you're looking for. Since the LEDs are always powered, you need only be concerned with the output of the phototransistor. DMM is fine; no scope necessary. An opto going bad is not completely unknown on these drives. (I have a couple of the 842s--good drives, otherwise) Diskette drives really are non-intelligent devices... --Chuck
[cctalk] Re: Qume 842 8" Disk Drive Question
On 1/31/24 13:03, Mike Katz via cctalk wrote: > Michael, > > Thank you, that was what I was planning as my next step. I haven't > checked to see if the service manual has a full schematic. > > The main purpose of my message on here was to see if I was missing > something obvious like an option trace cut or something like that that I > missed when I checked the manual. > > Thanks again, Mike - There is indeed a schematic in the 842 service manual PDF page 87 is what you're looking for. Since the LEDs are always powered, you need only be concerned with the output of the phototransistor. DMM is fine; no scope necessary. An opto going bad is not completely unknown on these drives. (I have a couple of the 842s--good drives, otherwise) Diskette drives really are non-intelligent devices... --Chuck
[cctalk] Re: Qume 842 8" Disk Drive Question
That is one of the tests recommended in the service manual. It's on my list of things to check. Thank you... On 1/31/2024 2:17 PM, Chuck Guzis via cctalk wrote: On 1/31/24 11:12, Mike Katz via cctalk wrote: I have not yet tried installing terminating resistors... That might help. It's also possible that the LED/phototransistor for the SS index position is faulty. The two LEDs (SS and DS) are connected in series, so you know that at least one isn't open. Grab your DMM and check the voltage levels on pins A6 and A7 on connector J2. They should change as the beam is broken in each with a piece of tinfoil or something else opaque. --Chuck
[cctalk] Re: Qume 842 8" Disk Drive Question
Michael, Thank you, that was what I was planning as my next step. I haven't checked to see if the service manual has a full schematic. The main purpose of my message on here was to see if I was missing something obvious like an option trace cut or something like that that I missed when I checked the manual. Thanks again, Mike On 1/31/2024 2:29 PM, Michael Thompson wrote: Connect an oscilloscope to the output of the single-sided sensor and see if it works. If so, trace the signal through the logic and see if it gets to the I/O connector that goes to the greaseweazel. On Wed, Jan 31, 2024 at 2:38 PM Mike Katz via cctalk wrote: I have recently acquired a Qume Model 842 double sided 8" disk drive. I have reset all of the settings to factory default and hooked it up to my greastweazle. The drive works perfectly for double sided disks (using the appropriate index hole). However, the greaseweasel reports no index pulse when I put a single sided diskette in the drive. I have attempted to clean out the sensor for single sided diskettes to on avail. Does any one have any ideas? The grease weasel works perfectly when I connect SA-800 drives. I have not yet tried installing terminating resistors in the Qume. Thank you in advance for your help, Mike
[cctalk] Re: Qume 842 8" Disk Drive Question
On 1/31/24 11:12, Mike Katz via cctalk wrote: > I have not yet tried installing terminating resistors... That might help. It's also possible that the LED/phototransistor for the SS index position is faulty. The two LEDs (SS and DS) are connected in series, so you know that at least one isn't open. Grab your DMM and check the voltage levels on pins A6 and A7 on connector J2. They should change as the beam is broken in each with a piece of tinfoil or something else opaque. --Chuck
[cctalk] Re: Qume 842 8" Disk Drive Question
Connect an oscilloscope to the output of the single-sided sensor and see if it works. If so, trace the signal through the logic and see if it gets to the I/O connector that goes to the greaseweazel. On Wed, Jan 31, 2024 at 2:38 PM Mike Katz via cctalk wrote: > I have recently acquired a Qume Model 842 double sided 8" disk drive. > > I have reset all of the settings to factory default and hooked it up to > my greastweazle. > > The drive works perfectly for double sided disks (using the appropriate > index hole). > > However, the greaseweasel reports no index pulse when I put a single > sided diskette in the drive. I have attempted to clean out the sensor > for single sided diskettes to on avail. > > Does any one have any ideas? > > The grease weasel works perfectly when I connect SA-800 drives. > > I have not yet tried installing terminating resistors in the Qume. > > Thank you in advance for your help, > >Mike > > On 1/31/2024 12:56 PM, Martin Bishop via cctalk wrote: > > Ah, PPC VME cards, add VXworks, funky coprocessors, COTS IO and you have > definitely got something best avoided : details would involve libations. > > > > The conduction cooled chassis are OK and worth repurposing. > Contrariwise the VME bus is best avoided, whether classic 32b VME or the 64 > bit revision. However, the connectors for VME 64x backplanes and the form > factor have merit, but that is to depart from the past. > > > > Martin > > > > -Original Message- > > From: Wouter de Waal via cctalk [mailto:cctalk@classiccmp.org] > > Sent: 31 January 2024 18:34 > > To: cctalk@classiccmp.org > > Cc: Wouter de Waal > > Subject: [cctalk] Re: Vmebus > > > > > >> Anyone have a VMEbus system they use at least occasionally? If so, what > >> make/model/config? > > I still use a couple of PPC VME boards (DY4 / Curtiss Wright > 182/183/184, both Conduction-Cooled and Air-Cooled) to test the tail end of > hardware that we are still shipping (by now EOL and basically NOS). > > > > But it's work, I don't find them interesting. > > > > If someone here has the warm fuzzies for PPC VME, we can talk :-) > > > > W > > > > -- Michael Thompson
