From: pfjw@aol.com   
      
   On Sunday, January 12, 2014 5:11:25 PM UTC-5, hugeshows wrote:   
   > Ok, pics coming soon...   
   >    
   >    
   >    
   > First step was to take voltage measurements off the bias and HV+ rails.    
   Here's what I got on my S-5000.  By the way, there are two variants of the   
   S-5000 that I will discuss later, basically the older, longer version and the   
   newer, shorter version.     
   The one I am working on here is one of the shorter types.   
   >    
    A few things out in the deep background here:   
      
   a) Voltages at the wallplate: These days, with average household electrical   
   use being anywhere between 50% and 200% greater than it was when that Sherwood   
   was 'new', Utilities that have not significantly upgraded their final   
   distribution systems (most)    
   have increased the voltage in those systems. It is not uncommon for us to see   
   up to 130V commonly at the wallplate at our house these days. And 5% over the   
   'nominal' 120V would account for most of your B+ variations.    
      
   Do you have access to a variac such that you might reduce the input voltage to   
   115V or so (much closer to what would have been the case in the 1960s   
   throughout most of the US)?    
      
   b) Selenium diodes decay over time (and when they fail it can be quite   
   spectacular and leave you gasping in amazement). As they decay their   
   resistance increases.    
      
   My guess is that your selenium diodes are 'out' about 10% - so the higher line   
   voltage overcomes some of that. NOTE and WARNING: if I am correct in that   
   assumption, those diodes are closing in on the failure point. Get that block   
   (or individual units)    
   replaced ASAP.    
      
   I am not above installing the occasional dropping resistor in some of my   
   equipment that was designed against a typical wallplate voltage of 110V or so   
   - most 'stuff' made in the 1930s and 1940s. Post WW-II, nominal was about   
   115V, into the 1980s, mostly    
   around 120V. And from about 2000, commonly well over that voltage. Filaments   
   do not like voltage in excess of their rating. 5% high typically will   
   translate to a 40% drop in life. AND, despite anecdotal and cult beliefs to   
   the contrary, nor do they like    
   low voltage very much either. Look up 'lazy cathode' and other phenomenon   
   along those lines. Generally, there is nothing much wrong with 5% low. Beyond   
   that and the consequences are worse than the benefits. Interesting aside -   
   clearing 'lazy cathode' (   
   AKA 'rejuvenation' in some circles) involves running filaments at a high   
   voltage under controlled conditions. So be aware.    
      
   c) Drifted resistors - resistor technology has changed (mostly for the better)   
   since the 1960s. These days, even 'cheap' resistors are typically well within   
   5% however they are marked. But older compositions often drifted - usually   
   higher. It is always a    
   good idea to check all the resistors.    
      
   Best of luck with this - it is a worthwhile endeavor.    
      
   Hum in the pre-amp: Given the extra amplification of the phono-stage, it will   
   exaggerate any hum in the system that may not show up at from the line-level   
   inputs. But, as it happens, most sources of hum in the phono section will be   
   related to bad    
   shielding, and/or a shield that is grounded at both ends (or the one end that   
   should be connected is not). Start with the simple stuff such as physical   
   damage or a failed connection. Then, look for the obvious - caps.    
      
   Never mind Andre - he is neither of consequence nor any particular use. Note   
   also that the pictures (of himself) he allows are over 30 years old... There   
   is far more ego than substance going on there.    
      
   Peter Wieck   
   Melrose Park, PA   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)