From: legg@nospam.magma.ca   
      
   >>A 'bubble' is a definite sign of a paint defect at time of mfr..   
   >>>   
   >>   
   >>I've never come across that before; just assumed it had blown through   
   >>over-current. I was *convinced* I was really on to something. I   
   >>suppose I could excavate the hole out and see how far down it goes   
   >>down. I might do that tomorrow just out of idle curiosity.   
   >   
   >Well, before I got around to that, my Ferrograph, which had just got   
   >back from a *very* expensive refurb, presented with the exact same   
   >problem: zero recording to tape despite plenty of audio input. Since   
   >the F'graph was still under warranty from the servicing people, I   
   >called them up and complained (politely - fortunately, as it   
   >happened). The chap on the phone said, "have you been playing old   
   >tapes on it?" I said, "Yes." He said, "Give the heads a good clean,   
   >then." I said, "They don't look dirty." He said, "Give 'em a good   
   >clean anyway and see if that fixes it." So I did (not having any faith   
   >it would help in the least, however). Nevertheless, full recording was   
   >instantly restored! So I thought I'd try the same thing with the Uher   
   >- and despite the heads looking perfectly clean, that worked too!   
   >It's been nearly 50 years since I last used reel to reel tapes and it   
   >seems I'd forgotten a basic piece of regular maintenance and that was   
   >the cause of my problem. I'd spent *hours* going through all the   
   >circuitry looking for anomalous voltage readings and finding none,   
   >squirting test signals into the amp chain and not finding any red   
   >flags there, not to mention the bias oscillator and the AGC. Whilst   
   >all the time, the solution was a simple bit of housework.   
   >Back in the day, we didn't need to worry about oxide-shedding, but old   
   >tapes age the same as we do, it transpires; some worse than others.   
   >Ampex are the *worst* in this respect, I've learned. Don't play old   
   >Ampex. Don't buy NOS Ampex. Google "sticky shed" for more info and   
   >don't fall into the same rabbit hole I did!   
      
      
   -known good test media (your reference)   
   -cleaned, demagnetized heads and transport (normal maintenance)   
   -rubber parts (degeneration)   
   -felt parts or anything dependent on adhesive (missing/moving)   
   -lubrication points (dirty or dry)   
   -any manually 'adjustible' parts (user damage)   
   -connectors (wear and tear)   
   . . . . . electronics from power input to signal output.   
      
   Hasn't changed in 80yrs, regardless of format or end use.   
      
   RL   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)