captainvi


Well I thought I'd jump back in here with an update on my progress. I ordered and installed a replacement capstan flat belt from Adams Manufacturing.. After installing this belt there was no more bumping from the old misshapen belt. then, I had three pinch rollers. One is from this machine and the other two were from junkers I had in the shop. The rubber on all of them was slick but seemed pliable and I worked on two of them with sandpaper and then lacquer thinner. I finished off with rubber restorer and then cleaned them off with 99% anhydrous isopropyl. After this treatment The rollers felt a bit more "grippier" if that's the correct description but still were not what I would have liked to see. However taking a fresh look at the 1KHZ tone on the test tape with the scope immediately after installing one of the "restored" rollers showed that the machine was now running on speed. So I feel foolish to admit that it seems that I had overlooked the most basic thing, the capstan roller, as being the primary governor of speed.


** Hallelujah !!



So I tried a few of my old tapes to see how they sounded. Some of these tapes were 1800 ft and I noticed that they would play for a coupe of songs and then start slowing down.

** Old tape get sticky and requires many passes through a machine to clean up, you may need to clean the heads with ISO over and over too.


I had a sealed brand new roll of Scotch 206, which is a 1200 ft low noise mastering tape as it's so called. I made a fine sounding recording on this tape. Then I tried playing the 3 3/4 pre recorded Bob Dylan tape. Let me tell you when Bob Dylan is off speed there is no mistaking it. So while this was running I gently increased the take up torque with my finger and the tape seemed to sound fine as long as I kept the tension up. As soon as I relaxed it a bit the speed would waver.

** The reel of 206 is probably sticky too - creating extra back tension that the capstan has trouble pulling through.



So now I know that for certain I need to resolve the pinch roller issue


** Sanding the surface smooth while spinning the roller in a bench drill has always worked for me.

For a R-R machine to work properly, so many things have to be just right.

Not the least of which is the tape itself.


.... Phil