> -----Oorspronkelijk bericht----- > Van: cctalk [mailto:cctalk-boun...@classiccmp.org] Namens Chuck Guzis via > cctalk > Verzonden: woensdag 6 september 2017 8:09 > Aan: CCtalk <cctalk@classiccmp.org> > Onderwerp: Re: HP 7970B Capstan? > > On 09/05/2017 10:47 PM, David Collins wrote: > > From my old HP CE days you could always get black off the capstan if > > you used alcohol or similar (never recommended). The key thing is it > > shouldn't be sticky/gooey. > > I noticed the issue by starting a read from load point and observing that the > bit > timing and data was all over the place until things came up to speed. I was > getting different data with each try. > > I pulled the capstan off, cleaned the powdery stuff off with isopropanol > and gave it a 30 minute soak in methyl salicylate and isopropanol. The > capstan comes out clean (no more shedding) and firm. > > I also noticed that the bits of foam on the inside of the capstan had > degraded to > goo. I replaced those with some new foam. > > The read results have improved considerably. Not perfect, but much better. > > --Chuck
Chuck, The tacho is a combined motor generator unit, it could be a good idea to read the adjustment procedures for the capstan tacho. The behavior is electronic controlled and adjustable. You can find the manual at the HP Museum site: http://www.hpmuseum.net/document.php?hwfile=2807 7970CEAdjusment...etc shouldn't be difficult to find. The speed and transient behavior of the capstan should be checked and possibly adjusted. You should also check if the capstan turns easy without noise. -Rik
