{"product_id":"sequential-circuits-prophet-5-rev-2-midi","title":"Sequential Circuits Prophet 5 Rev 2 MIDI","description":"\u003cdiv class=\"gmail_default\"\u003eSequential Circuits Prophet 5 Rev 2 with Midi for sale at Soundgas following an extensive and detailed overhaul\/upgrade for the current owner. \u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003e\u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003eThis synth has been totally restored to the highest level by one of the best vintage synth techs in the business for the owner who intended to keep and play it for many years but unexpected expenses mean it's regrettably for sale. You will not find a better Rev 2.\u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003e\u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003eNo expense or time spared - took nearly 18 months from start to finish and is wonderful, reliable and a joy to play. It has Midi. The notoriously fickle keyboard has been upgraded with a new Fatar keybed which is a big improvement over the original (and won't require regular maintenance. A new power supply was fitted as well as many more new parts to create the ultimate reliable Rev 2.\u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003e\n\u003cspan\u003eBelow is the full report from the tech which does not include details\/cost of the meticulous panel re-screening (nor of the replacement keybed) - which turned out to be an extended and expensive process but worth the time\/cost as it is virtually indistinguishable from the original factory finish.\u003c\/span\u003e\u003cspan\u003e\u003c\/span\u003e\u003cspan\u003e\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003e\n\u003cbr\u003eService Report\/Notes - completed May 2026\u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003e\n\u003cbr\u003e• Full service requested. Subsequently, new keybed and new pots requested.\u003cbr\u003eConcise Summary of Work Undertaken:\u003cbr\u003e• Keybed replaced with new Fatar system and tested OK.\u003cbr\u003e• All panel pots replaced (originals had already been previously replaced with dubious substitutes and\u003cbr\u003ethe pots glued onto the shafts); knob springs also replaced.\u003cbr\u003e• Power supply, mains cable and plug replaced and tested OK.\u003cbr\u003e• New memory kit installed, replacing original unreliable RAM chips and the firmware EPROMs. Unit\u003cbr\u003enow runs v7.0C firmware which provides cassette support.\u003cbr\u003e• Various missing fasteners and feet replaced.\u003cbr\u003e• Z80 CPU replaced (died during calibration).\u003cbr\u003e• New battery fitted, with current measurement resistor.\u003cbr\u003e• 2 x bad SSM2020 dual VCAs replaced.\u003cbr\u003e• Unit fully calibrated.\u003cbr\u003e• Factory patches loaded.\u003cbr\u003e• Unit provided no audio or boot initially.\u003cbr\u003e• Pot knobs found to be glued to pot shafts, which are themselves not the original types. Knobs\u003cbr\u003eremoved with some difficulty and cleaned of glue deposits. New knob springs fitted. All 26 pots\u003cbr\u003ereplaced with remanufactured set matching the original design.\u003cbr\u003e• Panel sent for reprinting.\u003cbr\u003e• Replaced two badly damaged pins in 20-pin DC connector on Board 3 (+\/-15V pins).\u003cbr\u003e• Rebuilt 3-pin DC power connector harness powering Board 4.\u003cbr\u003e• Replaced battery with new 3.6V type. PCB pad for +ve contact is unuseable; made wire tail for +ve\u003cbr\u003econtact and attached this directly to steering diode pin.\u003cbr\u003e• Replaced IC sockets for EPROMs, CPU and scratch RAM.\u003cbr\u003e• Achieved unit boot; panel switches working but no pot activity. Traced problem to failed comparator\u003cbr\u003eU339 (LM311); replaced U339 and recovered pot operation OK.\u003cbr\u003e• Removed original power supply and fitted new purpose-built type, including toroidal mains\u003cbr\u003etransformer. Tested new supply OK.\u003cbr\u003e• Removed original keybed and fitted new 5-octave Fatar type with purpose-built mounting frame.\u003cbr\u003eFitted new wheel panel (the Fatar keybed is fractionally wider than the original) and made minor\u003cbr\u003emetalwork modifications to remount wheels.\u003cbr\u003e• Unit stopped booting. Traced problem to two failed patch RAM ICs (HM3-6508). These are long\u003cbr\u003eobsolete and known to develop problems. Removed all eight patch RAM ICs and all EPROMs, and\u003cbr\u003einstalled new memory upgrade kit which provides single IC for patch memory and single IC for\u003cbr\u003efirmware. Still no boot. Noticed IC309 (RAM write-protect logic) is the wrong family (74HCT); should\u003cbr\u003ebe 74HC. Replaced IC309 with correct type. Recovered boot and operation OK.\u003cbr\u003e• Reseated all socketed ICs.\u003cbr\u003e• Rough-tested all 10 VCOs OK.\u003cbr\u003e• Calibrated instrument to factory spec. Replaced 2 bad SSM2020 dual VCAs (U422 and U413) which\u003cbr\u003ewere preventing Poly-Mod adjustment.\u003cbr\u003e• Z80 CPU died during calibration process. Replaced with Sharp LH0080A (Z80 equivalent).\u003cbr\u003e• Loaded original factory patches.\u003cbr\u003e• Replaced various missing PCB and case fasteners, and 2 missing feet.\u003cbr\u003e• Performed electrical safety PAT test.\u003cbr\u003e• Tested all functions OK.\u003cbr\u003e18th May 2026\u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003eParts:\u003c\/div\u003e\n\u003cdiv class=\"gmail_default\"\u003eNew Fatar keybed purchased\/supplied by client\u003cbr\u003eNew panel pots (26) £300.00\u003cbr\u003eNew power supply £195.00\u003cbr\u003eNew RAM\/ROM memory kit £79.00\u003cbr\u003eCustoms charge for new pots £34.38\u003cbr\u003eCustoms charge for power supply £35.40\u003cbr\u003eCustoms charge for new keybed £74.96\u003cbr\u003eNew knob springs (26) £13.00\u003cbr\u003eReplacement PCB fasteners £4.00\u003cbr\u003eReplacement case fasteners and feet £12.00\u003cbr\u003eNew mains cable and plug £11.99\u003cbr\u003eReplacement CPU £12.00\u003cbr\u003eNew battery £11.90\u003cbr\u003eNew IC sockets £12.71\u003c\/div\u003e\n\u003cp\u003eSale on behalf of the owner.\u003c\/p\u003e","brand":"Soundgas","offers":[{"title":"Default Title","offer_id":64645035295097,"sku":null,"price":12000.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0555\/7796\/8739\/files\/SequentialCircuitsProphet5Rev2MIDI_1195.jpg?v=1789818427","url":"https:\/\/soundgas.com\/products\/sequential-circuits-prophet-5-rev-2-midi","provider":"Soundgas","version":"1.0","type":"link"}