#publison

DHM 89 B2: Found some weird vintage gear!

. . Repairing @zdar_war 's Publison DHM89B2 (cont') . This time, found a set of three linear chips gone bad: two LF356 (a lot of these op-amps are frequently found toasted in 30-40 years old gear, unfortunately 😥) and one LM311 comparator. All three belong to the A/D or D/A conversion section. . #Publison #PublisonSystems #DHM89 #DHM89B2 #PublisonDHM89B2 #VintageDigitalFXBox #VintageDigitalPitchShifter #PhilippeZdar #Cassius #Motorbass #Repair #PiscineATokyo #StudioPiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BumO9SWB4hy/?utm_source=ig_tumblr_share&igshid=11r19c87myim8

. . WOW WOW WOW!!!!!!!!!!!!!!!!!! Looks like @soundgasltd 's #Publison #InfernalMachine90 is FINALLY back to full work!!!!!!!!!!!!!! I AM SO RELIEVED!!!! ☺️☺️☺️☺️ . SMPTE board is now fully working, AT LAST!!! 👌👌👌👌Main CPU recognizes the optional PCB, meaning that all SMPTE algorithms are accessible again. And the most beautiful cherry on the cake is that the remote control finally works normally, too!!!!!!!! 😍😍😍😍😍😍😍😍😍😍😍😍😍😍😍😍 . Thanks to the help of another huge Publison fan, @infernalemachine in Bordeaux (who VERY kindly lent me his own working unit so I could compare both units), I've been able to trace the issue to a rather "simple" fault... in itself: there had been a swap of two ICs on this previously non-working SMPTE card! 😔Problem is, as Publison never released ANY technical information about their machines, and as they used to sand off the part number on EVERY IC in their machines, it was almost impossible to guess which part had been swapped!!! . Anyway, please note that I got this far (that is, solving the most important issues in this IM90) WITHOUT any official schematic... Then I guess I could deserve some gratitude from Mr. Dean himself (the founder of Publison), couldn't I? ☺️☺️☺️ . So, thanks again to these friends for their MUCH appreciated help and support: @infernalemachine of course 😍 @soundgasltd for their trust and confidence ☺️ and @watersoundpro for the highly spiritual support to my endeavours in repairing the wonderful early digital machines from Publison! 😍😍😍😍😍😍😍 . #PublisonSystems #IM90 #InfernalMachine #PublisonInfernalMachine #PublisonIM90 #VintageDigitalFXBox #VintageDigitalMultiFXBox #FirstCommercialProAudioOutboardWithDSPs #SoundGasLtd #SoundGas #SoundGasUK #Repair #PiscineATokyo #StudioPiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/Bud26Z_FWhx/?utm_source=ig_tumblr_share&igshid=3uscmrxavsik

. . @inagrm 's #Publison #DHM89B2 & #KB2000 combo has finally come back home in the studios of the venerable, 60 years-old Groupe de recherches musicales (very close to the famous Maison de Radio France) 😊😊😊 . #PublisonSystems #DHM89 #PublisonKB2000 #PublisonDHM89B2 #VintageDigitalFXBox #VintageDigitalPitchShifter #Restoration #InaGRM #GRM #InstitutNationalDeLAudiovisuel #GroupeDeRecherchesMusicales #PiscineATokyo #StudioPiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager (à Ina-Grm) https://www.instagram.com/p/BuWftKahn-h/?utm_source=ig_tumblr_share&igshid=6cspg96h3pxr

. . Last tests before @inagrm 's #Publison #DHM89B2 & #KB2000 combo returns home tomorrow after a loooong restoration... ☺️ . #Publison #PublisonSystems #DHM89 #DHM89B2 #PublisonDHM89B2 #VintageDigitalFXBox #VintageDigitalPitchShifter #Restoration #InaGRM #GRM #InstitutNationalDeLAudiovisuel #GroupeDeRecherchesMusicales #PiscineATokyo #StudioPiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BuTXdblFXLa/?utm_source=ig_tumblr_share&igshid=do2nwlo5sfe2

. . @soundgasltd 's #Publison #InfernalMachine is still playing tricks on me... 😥 . This time, after having repaired channel A's DSP board yesterday so it now works as channel B, I noticed that all algorithms related to the SPMTE board are not available (upper left picture)... though the said board (upper right pic) is effectively present, installed and fully connected! 😥 . Not surprisingly, the remote control is acting berzerk (lower left pic) 😱 (its send/receive serial signals actually pass through the SMPTE PCB)... . A first close up inspection of the SMPTE card shows that a bypass tantalum cap for a upply rail (and its associated fuse resistor) must have had a very hard time (lower right pic)... replacement is in order, then! 😉 . Looks like there is still repair work for the Good Doctor Prager to be done on this Infernal Machine... which can be truly "infernal", from a service tech standpoint at least! ^^ . #PublisonSystems #IM90 #InfernalMachine90 #PublisonInfernalMachine #PublisonIM90 #VintageDigitalFXBox #VintageDigitalMultiFXBox #FirstCommercialProAudioOutboardWithDSPs #SoundGasLtd #SoundGas #SoundGasUK #Repair #PiscineATokyo #StudioPiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BuGOvGglZkc/?utm_source=ig_tumblr_share&igshid=ezga69epkw4

. . Taming the famous (and famously tacky AND tricky!!!), wonderful #Publison #InfernalMachine: HURRAYYYYYYYY!!!!! VICTORYYYYYYYY!!!!! CHANNEL A IS WORKING AGAIN, AT LAAAAST!!!!!!!!! 😊😊😊😊😊😊😊😊😊😊😊😊😊😊 . I feel SOOOOO relieved to have FINALLY found the (effectively) "missing link": a track on Channel A's DSP board was cut between two chips (an LS393 dual 4-bit binary counter and its driving LS73 dual J-K flip-flop), so that the DSP chip never had access to the DMA circuitry to process, send to the 64 memory chips and then back to the DAC channel A's 16 bits of digital audio!!!! 😥😥😥 . The cut was barely visible, on a track that is very fine in width (as are 95% of all the other tracks on that board, by the way)... 😨 . Thanks to having redrawn the needed section of the schematics (daunting task it is! and it's just a SMALL part... 😪 see upper right picture) using the other, working channel's board as a model, I've been able to trace down the missing link and then fixed it with a short Kynar wire (upper left picture) 👍👌😉 . Now channel A is FINALLY back to work!!!!! 😊😊😊😊 ...and I know someone at @soundgasltd who might be as much happy as I am! ☺️ . #PublisonSystems #IM90 #InfernalMachine #PublisonInfernalMachine #PublisonIM90 #VintageDigitalFXBox #VintageDigitalMultiFXBox #FirstCommercialProAudioOutboardWithDSPs #SoundGasLtd #SoundGas #SoundGasUK #Repair #PiscineATokyo #StudioPiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BuEP5sHF0P-/?utm_source=ig_tumblr_share&igshid=168h195yauqx7

. . Follow-up to the previous post (restoring the PSU of Levitator Studio's #Publison #DHM89B2) . All seven supply rails are there: +5V for most of the logic section (TTL), +15V and -15V for some analog circuitry, +12V and -5V for the DRAM chips, and +7.5V and -8V for most of the analog section and for a large part of the CMOS logic gates . 👌😊👍 . #Publison #PublisonSystems #DHM89 #DHM89B2 #PublisonDHM89B2 #VintageDigitalFXBox #VintageDigitalPitchShifter #Repair #LevitatorStudio #PiscineATokyo #StudioPiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/Bt1pMw7h5lJ/?utm_source=ig_tumblr_share&igshid=hp8awey84opm