New recruitment: a 1/4" STUDER A820

yjwu

Well-Known Member
Jun 28, 2011
78
12
913
Taipei, Taiwan, Republic of China
I got this STUDER also in non-functional state: none of the green LED's were lit as I got it on May 31, 2014; only a pulsing rotation of the take-up reel table at power on. After half month's struggle I located a fault of two gold fingers on master MP board, the machine started self-diagonosis with no error! It took me another day to really make it work: a MP7524 D/A convertor on spolling motor controller failed; which made the tape deck section fail to play any tape.

I had carried out many experiments to bring the wow-and-flutter figure low. The final version of the test was to fine-tunning R41 on tacho sensor board (1.021.695.81) at the vicinity of 50% duty cycle of TD-TCH1 (IC1/pin 2); monitoring the total harmonic distortion of a recorded 1kHz signal @ 3.75ips at lowest figure from a Tektronix AA5001. The 1kHz reference signal was from a mono/stereo switch with test tone generator borrowed from my STUDER A810.

My impression so far was: there was still room for improvement.
 

Attachments

  • DSC08689_6.JPG
    DSC08689_6.JPG
    78 KB · Views: 2,532
  • DSC08692_6.JPG
    DSC08692_6.JPG
    58.9 KB · Views: 844

About us

  • What’s Best Forum is THE forum for high end audio, product reviews, advice and sharing experiences on the best of everything else. This is THE place where audiophiles and audio companies discuss vintage, contemporary and new audio products, music servers, music streamers, computer audio, digital-to-analog converters, turntables, phono stages, cartridges, reel-to-reel tape machines, speakers, headphones and tube and solid-state amplification. Founded in 2010 What’s Best Forum invites intelligent and courteous people of all interests and backgrounds to describe and discuss the best of everything. From beginners to life-long hobbyists to industry professionals, we enjoy learning about new things and meeting new people, and participating in spirited debates.

Quick Navigation

User Menu

Steve Williams
Site Founder | Site Owner | Administrator
Ron Resnick
Site Co-Owner | Administrator
Julian (The Fixer)
Website Build | Marketing Managersing