Gary, 

Where did you get those TIL311's from?  A local surplus store here has put a 
bunch of them on ebay that match this description.  If you did buy these from 
Active Surplus, I know the store manager there and I'll do what I can to help.  

Cheers,
Josh Bensadon


Date: Sat, 28 Jun 2014 23:49:00 -0400
From: [email protected]
To: [email protected]
Subject: Re: [N8VEM-S100:4412] v20-16, z80-20 and chip counterfeits


  
    
  
  
    Curt -

      

      I purchased two Z84C0020PEC's that were also questionable.  One
      was dead, one runs ok at 8mhz (I haven't tried faster clock speeds
      yet).  They had identical top printing and date codes, but the
      molding marks on the bottom were different.  The dead chip was
      replaced without question with one that also works fine at 8mhz.

      

      Also a recent batch of TIL311's were used pulls (advertised as
      new) and 3/10 were dead in whole or part.  They had shortened
      tinned leads and obvious signs of removal.

      

      I could write pages about counterfeit capacitors - my primary
      hobby is vacuum tube audio gear.  My experience is that 100% of
      Chinese capacitors are faked.

      

      If Mouser or Digikey carries the parts it's worth the extra cost!

      

      - Gary

      

      On 6/28/2014 10:44 PM, curt mayer wrote:

    
    
      I've got a 8088 cpu blank, and a z80 cpu populated.
          I bought a 10 chip lot of z84c0002pec's from ebay, and was a
        bit horrified when I got them to find
        that they smelled of new paint.  identical fronts, but the
          backs showed different countries (indonesia and phillipines),
          all with different mold imprints.
        

        
        obviously shenanigans. 
        

        
        so, I wired up a 20mhz test rig for the z80's, using a
          derivative of dunfield's no-ram monitor (i disassembled it and
          added a lot more code), and not a one tested
        out at 20 mhz.  one limped at 16, 2 ran at 12, and the rest
          were good at 8.  all tested as cmos: the out (C),F instruction
          sends FF, the nmos sends 00.
        

        
        for 15 bucks, I got a bunch of mildly useful z80s of
          unknown actual characteristics.
        

        
        anyhow, now i want to build the 8088 board with V20's - NEC
          has a part number for dip-40's at 16mhz.  70108hcz-16.  lots
          of them available on ebay from china.
        

        
        any experiences here before I become the ebay counterfeit
          chip crash test dummy?
        

        
        --curt
      
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