. . Reparing @zdar_war 's Publison DHM89B2 . This unit has several small but yet annoying issues that the great Mr. Zdar from the @cassius fame asked me to fix . In this first episode in a series, I had to start by correctly rebuilding the +5V rectifying and filtering section of the PSU. There was around 1Vpp of noise on this rail 😨 so I suspected that the old rectifier bridge (that was put there to replace the original bridge made up of four MR751, 22 amps diodes BTW) could have aged... then I changed it with a fresh new GBPC2501 25 amps bridge... and added thermal pastebeneath it so the heat generated could dissipate more easily 👌 . Also replaced the reservoir cap and, most of all, cleaned the mess leaved by the person who worked on replacing the discrete diodes with the old bridge... As one can see on the lower row of pictures, it was certainly not done by The Good Doctor Prager's standards! 🤢 . Anyway, now the noise on the +5V line has been reduced to ~400 mV, which sounds more acceptable, given the very high count (almost 200!!!) of TTL chips on the digital board. Not so bad, isn't it? 😊☺️👌👍 . #Publison #PublisonSystems #DHM89 #DHM89B2 #PublisonDHM89B2 #VintageDigitalFXBox #VintageDigitalPitchShifter #PhilippeZdar #Cassius #Motorbass #Repair #PiscineATokyo #StudioPiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BtVwBIwBcNb/?utm_source=ig_tumblr_share&igshid=1fujzezo3bi0v
