#lexicon224digitalreverberator

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . While I was dusting the boards and cleaning their edge connectors (which were dirty like hell!), I decided to check all of the linear ICs on both the Analog Inputs and Analog Outputs PCBs... . Found out that the FOUR LF356 single op-amps that are at the very end of the audio signal path (right before the output transformers) were ALL toasted!!! Not surprisingly though, as not only this particular model of IC frequently goes bad when it's over 20-30 years of age, but also because, in the M224 signal path, these very ones are responsible for boosting the current of the analog output in a push-pull circuit (with the aid of two complementary, medium power transistors)... . Next and LAST step, for sure: powering the whole system on and testing it with audio signals 😉 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/Bus5MMfl2cT/?utm_source=ig_tumblr_share&igshid=16u436murgzgq

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Before reconnecting the remote head and testing it, there are still three things to do... . Thrird (and last), cleaning of the Remote Head itself was required, prior to reconnecting it to the mainframe. And in case you doubt that, just compare the first picture (after cleaning) to the second one (taken before)! 😉👍👌😊😍☺️ . So, the whole system is now completely ready for being fired up all at once... and see if it eventually boots up fine, or not! 😨😊 . Stay tuned... 😉 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BusgVbul6Vd/?utm_source=ig_tumblr_share&igshid=ivzj6l8ajyit

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Before reconnecting the remote head and testing it, there are still three things to do... . Second, refurbishment of the original, simple PSU section (rectifying of the 10Vac from the power transformer and on-board +5V regulation) on the lower board of the Remote Head. . Second picture shows obvious signs of tired diodes because of overheating; brown part of the left-hand, big axial cap says the same; and most of the thermal paste of the 7805 had dried 😪 . First picture was taken after replacement of the critical components of this circuit 👌😊 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/Bur-TLfFkuv/?utm_source=ig_tumblr_share&igshid=1n6ik6elidep5

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Before reconnecting the remote head and testing it, there are still three things to do... . First, replacement of the very old, leaking original batteries on the NVRAM Board with a moden Varta MemPac 😉👍 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/Bur8l-KldY4/?utm_source=ig_tumblr_share&igshid=jk6dylflw124

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Restoring the PSU section, step five (last but not least!): testing the restored and refurbished entire PSU. . Part two (the last one): 224 powered on, still no remote connected but all boards now plugged in: each of the six main supply rails registers within spec, and DC waveform is steady as can be! 👍👍👍😍😍😍😊😊😊 . +5V is at +4.96V / -5V is at -5.07V / +12V is at +12.0V / -12V is at -12.2V / +15V is at +15.3V / and -15V is at -15.3V. All fine, then! 👌 . Guess now's the time to reconnect the remote head and see if the CPU finally starts up fine... which I hope it will!!!! 🙏🙏🙏 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BurDx9qFs3H/?utm_source=ig_tumblr_share&igshid=xl95dihnsd23

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Last views of the reinstalled PSU before closing the lid. . Even the plexi window protecting the P.S.#1 Board from the user has been cleaned 😉 . ...but the question still remains: will the unit boot up properly, now the PSU has been wholly refurbished? 🤔🤔🤔🤔🤔 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BuqvpUolH87/?utm_source=ig_tumblr_share&igshid=mm0y1jqek0dt

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . No wonder the PSU section had issues: just a look at the underside of the top lid clearly shows that this very unit had (perharps often) heated too much, if not overheated sometimes... 😱😱😱 . Second picture is the same top lid after thorough cleaning ☺️👌 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BuqZ6gIFr2P/?utm_source=ig_tumblr_share&igshid=q1fiahz6i4st

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Restoring the PSU section, step five (last but not least!): testing the restored and refurbished entire PSU. . Part one: no card plugged-in, unit fired up... and the six supply rails are all still there (+15/-15V, +12/-12V and +5/-5V) 👍👌. . Next part: reinstalling the rear module inside the chassis and testing the PSU again, this time with all the cards plugged-in (but one at a time) 😉 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/Bun6rxElzrH/?utm_source=ig_tumblr_share&igshid=aqmfwf7my451

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Restoring the PSU section: step four (rebuilding P.S.#1 Board) is complete! 😊 . PCB is clean as can be, new 47mF reservoir capacitor (yeah, couldn't find the same one WITHOUT the threaded stud which is not used in the M224... 😔) has been installed to replaced the aged and burnt 45mF one, new 1000uF cap, new individual diodes, fresh thermal paste has been generously applied to the original R711 power double diode and, last but not least, the broken button cap for the power switch has been replaced with the exact same type and color 😉 . Guess that now's the time to reinstall the whole refurbished PSU into the chassis and test it... ☺️ . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/Bunz6WiFSq9/?utm_source=ig_tumblr_share&igshid=co8tp9qlbsa1

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Restoring the PSU section, step four: rebuilding P.S.#1 Board. . Let's get started! 😉 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BunzUBDF-Pp/?utm_source=ig_tumblr_share&igshid=1lc2j2b6vr7km

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Restoring the PSU section, step three (reassembling P.S.#3 Board with P.S.#2 Board onto the large heatsink) is over! 😊 . ...and the six power supply rails are all there: +15/-15V, +12/-12V and +5/-5V 👍👌 (though these were measured without the actual load of all the 224's circuits plugged-in: so, checking the efficiency of the rebuilt and reinstalled PSU will be the very last step of its restoration, after P.S. Board #1 is done 😉) . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/Bul9etDFMde/?utm_source=ig_tumblr_share&igshid=u9pllumpbz5p

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Restoring the PSU section, step three: reassembling P.S.#3 Board with P.S.#2 Board onto the large heatsink... . ...altogether with the two LM317K adjustable power regulators, the two 2N5886 PNP power transistors, as well as the TIP31A PNP power transistor, the 2N6394 thyristor, and the two MC7912A -12V regulators 👍 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/Bul28NklDlc/?utm_source=ig_tumblr_share&igshid=1qjqls93akuog

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Restoring the PSU section, step two (rebuilding P.S.#3 Board) is almost over: PCB is clean as can be and 95% repopulated 👍 . Left are the two power transistors (that will be screwed through the PSU heatsink to their respective wired sockets) and the three other power devices (one regulator, one transistor and a thyristor) which will have to be connected to their corresponding sockets on the PCB after they have been screwed onto the heatsink 😉 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BulWEVwlnWM/?utm_source=ig_tumblr_share&igshid=vkxh5ilz4rcb

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Restoring the PSU section, step two: rebuilding P.S.#3 Board. . Ready? Set? Go! 😉 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BulJgMClpp9/?utm_source=ig_tumblr_share&igshid=18cr35nic1zf9

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Restoring the PSU section, step one (rebuilding P.S.#2 Board) is almost over 👍 . Left are the three regulators that will have to be soldered only after they have been screwed onto both the board itself and the huge PSU heatsink 😉 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/Buiwjf0lhQk/?utm_source=ig_tumblr_share&igshid=gja0ravoy8q7

[piscineatokyo]

. . Fixing an old #LexiconPro #Model224 which does not start-up anymore (con't) . Restoring the PSU section, step one: rebuilding P.S.#2 Board... part by part 😉 . #Lexicon #M224 #LexiconM224 #Lexicon224 #Lexicon224DigitalReverberator #DigitalReverberator #VintageDigitalReverb #EarlyDigital #Repair #VintageElectronicsRepair #VintageProAudioEquipment #StudioPiscineATokyo #PiscineATokyo #TheGoodDoctorPrager #LeBonDocteurPrager https://www.instagram.com/p/BuhDHyHhLGq/?utm_source=ig_tumblr_share&igshid=pzzxjrf0qggf