On Sun, Nov 5, 2017 at 5:43 PM, Aaron Jackson via cctalk <cctalk@classiccmp.org> wrote: > Hi everyone, > > I have managed to hook up an RL02 drive to my PDP-11 (thanks to Dave > Wade for the drives) . This took me longer than I thought it would - I > tried with a flat ribbon cable with a DIY terminator going straight into > board , but couldn't get it to work. Removed the terminator, and the > fault light turned off. So that's positive. > > I tried to load a cartridge, which I had cleaned, inspected and > generally appears to be in good condition. It started to spin up and I > could hear it getting faster, but after 30-40 seconds the fault light > returns. I made a short video demonstrating this: > > https://www.youtube.com/watch?v=japwBBodO8U > > According to the manual the fault light can appear for the following > reasons: > > - Drive select error... Surely this would come on at the start? > - Seek time out error... I'd have to hear the heads move first > - Write current in heads during sector time error... Same as above > - Loss of system clock... The fault light would be on from the start. > - Write protect error... I don't think it got that far > - Write data error... Same as above > - Spin error... Is this the only remaining fault? > > So could the only cause be a spin error? I am wondering if the belt is > slipping or something like that? > > Can anyone offer some advice?
It's been some time since I worked on one of these and I don't have the printset to hand, but from what I remember the fault indicator circuit is triggered by a (logically) many-input OR gate. Probably a NAND in practice, which is why I said 'logically'. The inputs to said gate come from the circuits that detect various faults. What I do is to look at each of those inputs in turn and see what is triggering the fault indicator. Then work back from there. -tony
