{
  "format": "circuit-codex-reference",
  "version": 1,
  "id": "5g9",
  "url": "https://circuitcodex.com/amps/5g9/",
  "attribution": "The Analog Maker / Circuit Codex",
  "license": "https://creativecommons.org/licenses/by-sa/4.0/",
  "revision": "195289eab0b0e41029bffd6e34b65f01a84e553b",
  "scope": "DC and drawing checks have separate coverage. See included check results and the circuit page; not a dimensioned build template or a physical-build certification.",
  "metadata": {
    "id": "5g9",
    "name_style": "Tweed Tremolux-style",
    "family": "tweed",
    "era": {
      "start": 1957,
      "end": 1960
    },
    "wattage": 18,
    "tubes": [
      "12AY7",
      "12AX7",
      "12AX7",
      "6V6GT",
      "6V6GT",
      "5U4GB"
    ],
    "topology": {
      "rectifier": {
        "kind": "tube",
        "type": "5U4GB"
      },
      "bias": "fixed",
      "phase_inverter": "long-tailed-pair",
      "tone_stack": "single-knob"
    },
    "conventions": {
      "designators": "functional",
      "notation": "us"
    },
    "sources": [
      {
        "desc": "Fender 'Tremolux' Model 5G9 drawing (B-EI), two pages — in THIS copy page 1 is the layout and page 2 the schematic. PROVENANCE: every value and printed voltage recorded here was read from this copy, a CCITT stencil scan whose native rasters are 6518x4128 (701 ppi) and 6376x4450 (777 ppi) — el34world's PDF, reached through the Wayback Machine because el34world.com is unreachable from here. A lower-resolution copy of the same drawing is cited below; it is legible for topology but its native page rasters are only 1064x775 and 1494x976, and a first pass from it misread the tremolo oscillator's cathode resistor. Read at full native resolution: notice 'Voltages read to ground with electronic voltmeter. Values shown + or - 20%'; notes 'Late 5E9-A models are similar to this model' and 'All resistors are 1/2 watt, 10%, unless specified'. Iron block: POWER TRANS. 8160, CHOKE 14684, OUTPUT TRANS. 108; HT winding lettered 300 V AC each side of the centre tap. Printed voltages +370 (reservoir / OT centre tap), +368 (post-choke screen node and the tremolo bottle's plates), +310 (preamp and phase-inverter feed), +175/+175 (12AY7 plates), +2.5 (shared 12AY7 cathode), +210/+200 (phase-inverter plates), +27 (joined inverter cathodes), +25.5 (inverter tail junction), -69 (bias rectifier), -28 (bias divider / grid-leak junction), -27.5/-27.5 (6V6GT grids), and in the tremolo +270 (oscillator plate), +260 (cathode-follower cathode), +1.7 (oscillator cathode). Inputs: two Inst. and two Mic. jacks on 68 kOhm stoppers over a 1 MOhm leak; 12AY7 with 100k plate loads on one shared 820 Ohm / 25-25 cathode; each plate through .1-400 to its OWN volume pot's WIPER, both 1 M pots' remaining ends grounded and joined at the mixing node, with the 1 M Tone pot's wiper on that node (.0005-400 in from the Inst. coupler, .005-400 out to ground); .02-400 from the mixing node to the inverter. Long-tailed pair: 82k-5% and 100k-5% plate loads fed at their junction from +310, 470 Ohm from the joined cathodes to a tail junction, 10k from there to ground, both 1 M grid leaks returned to that junction and .1-200 from the cold grid to ground. Output: .02-400 couplers, 220k-220k grid leaks joined at the -28 V line, 470 Ohm-1W screen resistors, grounded cathodes. Supply: 5U4GB on a 300-0-300 winding, four 20-500 cans (two on +370, one each on +368 and +310), choke, 10k-1W to +310; bias from a selenium rectifier straight off one HT leg with no series feed resistor, two 8-150 cans and an 82k / 56k divider. Tremolo: 12AX7 phase-shift oscillator (100k plate load, 1500 Ohm cathode with 25-25, ladder .03-400 / .01-400 / .01-400 on 1 M returns, 2 M Speed with a 100k end resistor) direct-coupled to a cathode follower (220k cathode resistor) whose .1-400 output feeds a 1 M into the 250k Depth control in the bias line. Not reproduced here",
        "url": "https://web.archive.org/web/20150316142123/http://el34world.com/charts/Schematics/files/fender/Fender_TREMOLUX_5G9.pdf"
      },
      {
        "desc": "The same Fender 5G9 (B-EI) drawing at Schematic Heaven, page 1 schematic and page 2 layout. Cited because it is the live copy a reader can fetch today, and recorded honestly as the LOWER-RESOLUTION one: its native page rasters are 1064x775 and 1494x976, coarse enough that two chart digits cannot be separated on it. No value in this entry rests on it",
        "url": "https://schematicheaven.net/fenderamps/tremolux_5g9_schem.pdf"
      },
      {
        "desc": "Mojotone/Ampwares Fender field guide, 'Fender Narrow Panel Tweed Tremolux' — the line 1955-1960 at 18 W with tremolo, its schematics listed as 5E9 (55), 5E9-A (55-56) and 5G9 (57-60); 12AY7 preamp and two 6V6GT throughout, with the 5G9 alone on fixed non-adjustable bias and a 5U4GB rectifier. The production window and the 18 W rating recorded here come from this page; the circuit facts come from the drawing",
        "url": "https://mojotone.com/blogs/fender-field-guide/fender-narrow-panel-tweed-tremolux"
      }
    ],
    "verification": {
      "status": "draft"
    },
    "added": "2026-09-09T00:00:00.000Z",
    "contributors": [
      "TheAnalogMaker"
    ],
    "sections": {
      "V3": "excluded — the tremolo bottle: a running phase-shift oscillator (V3A) and the cathode follower direct-coupled to its swinging plate (V3B); neither has a static operating point, and the netlist header states the ~2 mA the pair would draw"
    }
  },
  "parts": {
    "notes": "The chassis carries two Inst. and two Mic. jacks, each channel's pair on its own two 68 kΩ stoppers over one 1 MΩ leak. The rectifier is lettered 5U4GB, as the drawing prints it; this corpus's 5U4G model is a 5U4G/5U4GA/5U4GB class approximation and nothing in the DC netlist instantiates it (see the netlist header). The tremolo bottle's parts are listed in full, but neither half's DC operating point is in the netlist (see the circuit story). Parts drawn only as annotations — mains cap, fuse, power switch, pilot lamp, jacks — are listed without designators. The transformers are numbered T1 (power) and T2 (output) under the archive's convention; the drawing letters them only by factory number, 8160 and 108, with the choke 14684.",
    "items": [
      {
        "ref": "R1n",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Inst. input grid stopper (jack 1)"
      },
      {
        "ref": "R2n",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Inst. input grid stopper (jack 2)"
      },
      {
        "ref": "RG1",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Inst. input grid leak"
      },
      {
        "ref": "RL1",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V1A plate load"
      },
      {
        "ref": "R3n",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Mic. input grid stopper (jack 1)"
      },
      {
        "ref": "R4n",
        "part": "Carbon comp resistor",
        "value": "68 kΩ · ½ W",
        "role": "Mic. input grid stopper (jack 2)"
      },
      {
        "ref": "RG2",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Mic. input grid leak"
      },
      {
        "ref": "RL2",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V1B plate load"
      },
      {
        "ref": "RK1",
        "part": "Carbon comp resistor",
        "value": "820 Ω · ½ W",
        "role": "Shared V1A/V1B cathode bias"
      },
      {
        "ref": "CK1",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "Shared V1A/V1B cathode bypass"
      },
      {
        "ref": "C1",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 400 V",
        "role": "V1A plate → the Inst. volume control's WIPER"
      },
      {
        "ref": "C2",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 400 V",
        "role": "V1B plate → the Mic. volume control's WIPER"
      },
      {
        "ref": "VR1",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ-A",
        "role": "Inst. volume — signal on the wiper, one end grounded, the other on the mixing node"
      },
      {
        "ref": "VR2",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ-A",
        "role": "Mic. volume — wired the same way"
      },
      {
        "ref": "VR3",
        "part": "Audio-taper potentiometer",
        "value": "1 MΩ-A",
        "role": "Tone — its wiper feeds the mixing node"
      },
      {
        "ref": "C3",
        "part": "Mica capacitor",
        "value": "500 pF",
        "role": "Inst. coupler node → the tone control's hot end. The sheet letters it .0005-400, so the drawing does give it a 400 V rating; house units carry sub-nanofarad parts in picofarads and without a working voltage"
      },
      {
        "ref": "C4",
        "part": "Film capacitor",
        "value": "0.005 µF · 400 V",
        "role": "Tone control's cold end → ground"
      },
      {
        "ref": "C5",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 400 V",
        "role": "Mixing node → phase-inverter hot grid"
      },
      {
        "ref": "RLA",
        "part": "Carbon comp resistor",
        "value": "82 kΩ · 5 % · ½ W",
        "role": "V2A plate load (hot side)"
      },
      {
        "ref": "RLB",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · 5 % · ½ W",
        "role": "V2B plate load (cold side)"
      },
      {
        "ref": "RGA",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "V2A grid leak, returned to the tail junction"
      },
      {
        "ref": "RGB",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "V2B grid leak, returned to the tail junction"
      },
      {
        "ref": "RTAIL",
        "part": "Carbon comp resistor",
        "value": "470 Ω · ½ W",
        "role": "Inverter cathode resistor (joined cathodes → tail junction)"
      },
      {
        "ref": "RT2",
        "part": "Carbon comp resistor",
        "value": "10 kΩ · ½ W",
        "role": "Inverter tail resistor (junction → ground)"
      },
      {
        "ref": "C6",
        "part": "Film capacitor",
        "value": "0.1 µF · 200 V",
        "role": "V2B grid to ground — the cold grid's signal reference"
      },
      {
        "ref": "C7",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 400 V",
        "role": "V2A plate → V4 grid"
      },
      {
        "ref": "C8",
        "part": "Coupling capacitor",
        "value": "0.02 µF · 400 V",
        "role": "V2B plate → V5 grid"
      },
      {
        "ref": "RG4",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "V4 grid leak to the −28 V bias line"
      },
      {
        "ref": "RG5",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "V5 grid leak to the −28 V bias line"
      },
      {
        "ref": "RS1",
        "part": "Carbon comp resistor",
        "value": "470 Ω · 1 W",
        "role": "V4 screen resistor"
      },
      {
        "ref": "RS2",
        "part": "Carbon comp resistor",
        "value": "470 Ω · 1 W",
        "role": "V5 screen resistor"
      },
      {
        "ref": "RL3",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "V3A oscillator plate load (to the +368 V node)"
      },
      {
        "ref": "RK3",
        "part": "Carbon comp resistor",
        "value": "1.5 kΩ · ½ W",
        "role": "V3A oscillator cathode bias"
      },
      {
        "ref": "CK3",
        "part": "Electrolytic capacitor",
        "value": "25 µF · 25 V",
        "role": "V3A oscillator cathode bypass"
      },
      {
        "ref": "C9",
        "part": "Film capacitor",
        "value": "0.03 µF · 400 V",
        "role": "Oscillator phase-shift cap, plate side"
      },
      {
        "ref": "C10",
        "part": "Film capacitor",
        "value": "0.01 µF · 400 V",
        "role": "Oscillator phase-shift cap, middle"
      },
      {
        "ref": "C11",
        "part": "Film capacitor",
        "value": "0.01 µF · 400 V",
        "role": "Oscillator phase-shift cap, grid side"
      },
      {
        "ref": "R7",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Oscillator grid leak to ground"
      },
      {
        "ref": "R8",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Oscillator phase-shift return to the cathode"
      },
      {
        "ref": "VR4",
        "part": "Potentiometer",
        "value": "2 MΩ",
        "role": "Speed (oscillator frequency)"
      },
      {
        "ref": "R9",
        "part": "Carbon comp resistor",
        "value": "100 kΩ · ½ W",
        "role": "Speed-control end resistor"
      },
      {
        "ref": "RK4",
        "part": "Carbon comp resistor",
        "value": "220 kΩ · ½ W",
        "role": "V3B cathode-follower cathode resistor — the oscillator's output load"
      },
      {
        "ref": "C12",
        "part": "Coupling capacitor",
        "value": "0.1 µF · 400 V",
        "role": "V3B cathode → the Depth control's feed resistor"
      },
      {
        "ref": "R10",
        "part": "Carbon comp resistor",
        "value": "1 MΩ · ½ W",
        "role": "Tremolo output feed into the Depth control"
      },
      {
        "ref": "VR5",
        "part": "Linear potentiometer",
        "value": "250 kΩ-L",
        "role": "Depth — sits in the −28 V bias line, carries no DC"
      },
      {
        "ref": "—",
        "part": "Jack",
        "value": "closed-circuit",
        "role": "Tremolo footswitch jack — shorts the oscillator's middle phase-shift node when plugged in and closed (annotation only)"
      },
      {
        "ref": "L1",
        "part": "Filter choke",
        "value": "Fender 14684",
        "role": "Reservoir → screen node (+370 V → +368 V)"
      },
      {
        "ref": "RD1",
        "part": "Power resistor",
        "value": "10 kΩ · 1 W",
        "role": "Rail dropper +368 V → +310 V (preamp and phase inverter)"
      },
      {
        "ref": "C15",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 500 V",
        "role": "Reservoir filter, +370 V (condenser box)"
      },
      {
        "ref": "C16",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 500 V",
        "role": "Filter, +370 V (condenser box)"
      },
      {
        "ref": "C17",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 500 V",
        "role": "Filter, +368 V screen node (condenser box)"
      },
      {
        "ref": "C18",
        "part": "Electrolytic capacitor",
        "value": "20 µF · 500 V",
        "role": "Filter, +310 V preamp node (condenser box)"
      },
      {
        "ref": "D1",
        "part": "Rectifier (bias)",
        "value": "selenium · silicon diode in modern builds",
        "role": "Bias-supply rectifier"
      },
      {
        "ref": "C13",
        "part": "Electrolytic capacitor",
        "value": "8 µF · 150 V",
        "role": "Bias-supply filter, −69 V node"
      },
      {
        "ref": "C14",
        "part": "Electrolytic capacitor",
        "value": "8 µF · 150 V",
        "role": "Bias-supply filter, −28 V line"
      },
      {
        "ref": "R11",
        "part": "Carbon comp resistor",
        "value": "82 kΩ · ½ W",
        "role": "Bias divider, upper leg (−69 V → −28 V)"
      },
      {
        "ref": "R12",
        "part": "Carbon comp resistor",
        "value": "56 kΩ · ½ W",
        "role": "Bias divider, lower leg to ground — sets the −28 V line"
      },
      {
        "ref": "V1",
        "part": "Preamp tube",
        "value": "12AY7",
        "role": "Both channel input stages (V1A/V1B)"
      },
      {
        "ref": "V2",
        "part": "Preamp tube",
        "value": "12AX7",
        "role": "Long-tailed-pair phase inverter (V2A/V2B)"
      },
      {
        "ref": "V3",
        "part": "Preamp tube",
        "value": "12AX7",
        "role": "Tremolo oscillator + cathode follower (V3A/V3B)"
      },
      {
        "ref": "V4",
        "part": "Power tube",
        "value": "6V6GT",
        "role": "Push-pull output (hot side)"
      },
      {
        "ref": "V5",
        "part": "Power tube",
        "value": "6V6GT",
        "role": "Push-pull output (cold side)"
      },
      {
        "ref": "V6",
        "part": "Rectifier tube",
        "value": "5U4GB",
        "role": "Full-wave rectifier (V6A/V6B)"
      },
      {
        "ref": "T1",
        "part": "Power transformer",
        "value": "Fender 8160 · 300-0-300 V AC",
        "role": "HT + heaters + rectifier filament — the drawing letters the HT winding 300 V AC each side of the centre tap, and the heater windings only as 'to all 6.3 volt heaters and pilot light'"
      },
      {
        "ref": "T2",
        "part": "Output transformer",
        "value": "Fender 108",
        "role": "Push-pull output"
      },
      {
        "ref": "—",
        "part": "Fuse",
        "value": "2 A",
        "role": "AC mains fuse (annotation only)"
      },
      {
        "ref": "—",
        "part": "Switch",
        "value": "SPST",
        "role": "AC power switch (annotation only)"
      },
      {
        "ref": "—",
        "part": "Film capacitor",
        "value": "0.05 µF · 600 V",
        "role": "Mains-to-chassis cap (annotation only)"
      },
      {
        "ref": "—",
        "part": "Pilot lamp",
        "value": "6.3 V",
        "role": "Pilot light (annotation only)"
      }
    ]
  },
  "publishedVoltages": {
    "source": "Fender 'Tremolux' Model 5G9 drawing (B-EI), printed voltages: +370 (reservoir / OT centre tap, driven), +368 (post-choke screen node), +310 (preamp and phase-inverter feed), +175/+175 (12AY7 plates), +2.5 (shared 12AY7 cathode), +210/+200 (phase-inverter plates), +27 (joined inverter cathodes), +25.5 (inverter tail junction), -69 (bias rectifier, driven), -28 (bias divider and grid-leak junction), -27.5/-27.5 (6V6GT grids), and in the excluded tremolo bottle +270 (oscillator plate), +1.7 (oscillator cathode), +260 (cathode-follower cathode)",
    "nodes": {
      "BS": {
        "chart": 368,
        "tol_pct": 8,
        "note": "post-choke node — the 6V6 screen feed and the tremolo bottle's plate supply. Solved through the 14684 choke's ESTIMATED 130 Ω DCR (stated in the netlist's header), so this is the one node whose prediction rests on an estimate rather than a printed value; internal target, tighter than the drawing's ±20%"
      },
      "BC": {
        "chart": 310,
        "tol_pct": 8,
        "note": "preamp and phase-inverter feed, one printed 10 kΩ · 1 W dropper below the screen node — internal target"
      },
      "PAY1": {
        "chart": 175,
        "tol_pct": 20,
        "note": "Inst.-channel 12AY7 plate, 100 kΩ from +310 V"
      },
      "PAY2": {
        "chart": 175,
        "tol_pct": 20,
        "note": "Mic.-channel 12AY7 plate, 100 kΩ from +310 V"
      },
      "KAY": {
        "chart": 2.5,
        "tol_pct": 20,
        "note": "shared 12AY7 cathode — both halves over one 820 Ω"
      },
      "PPIA": {
        "chart": 210,
        "tol_pct": 20,
        "note": "phase-inverter plate, 82 kΩ · 5 % (hot) side"
      },
      "PPIB": {
        "chart": 200,
        "tol_pct": 20,
        "note": "phase-inverter plate, 100 kΩ · 5 % (cold) side"
      },
      "KPI": {
        "chart": 27,
        "tol_pct": 20,
        "note": "joined inverter cathodes, above the 470 Ω"
      },
      "JPI": {
        "chart": 25.5,
        "tol_pct": 20,
        "note": "inverter tail junction (470 Ω / 10 kΩ), the return for both 1 MΩ grid leaks. '25.5' and '255' cannot be told apart on the low-resolution copy of this drawing; read unambiguously as +25.5 V at 777 ppi (see the sources cited on this page), which is also what the printed +27 V cathode one 470 Ω away requires"
      },
      "G61": {
        "chart": -27.5,
        "tol_pct": 20,
        "note": "V4 grid, fixed bias through a 220 kΩ leak from the −28 V line"
      },
      "G62": {
        "chart": -27.5,
        "tol_pct": 20,
        "note": "V5 grid, fixed bias through a 220 kΩ leak from the −28 V line"
      },
      "NBIAS": {
        "chart": -28,
        "tol_pct": 8,
        "note": "bias line — solved through the drawing's own 82 kΩ / 56 kΩ divider off the printed −69 V, not abstracted. The joined 220 kΩ grid leaks and the Depth control's cold end sit here; no DC flows through the Depth pot — internal target"
      },
      "SG1": {
        "chart": null,
        "note": "V4 screen, below the +368 V node through its own 470 Ω · 1 W. The drawing prints no screen voltage"
      },
      "SG2": {
        "chart": null,
        "note": "V5 screen, below the +368 V node through its own 470 Ω · 1 W. The drawing prints no screen voltage"
      },
      "GPIA": {
        "chart": null,
        "note": "phase-inverter hot grid — sits at the tail junction through its 1 MΩ leak. The drawing prints no voltage here"
      },
      "GPIB": {
        "chart": null,
        "note": "phase-inverter cold grid — the same, with the 0.1 µF · 200 V to ground beside it. The drawing prints no voltage here"
      }
    }
  },
  "operatingPoint": [
    {
      "node": "BS",
      "chart": 368,
      "sim": 368.507,
      "disputed": false,
      "dev_pct": 0.13777173913043614,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "post-choke node — the 6V6 screen feed and the tremolo bottle's plate supply. Solved through the 14684 choke's ESTIMATED 130 Ω DCR (stated in the netlist's header), so this is the one node whose prediction rests on an estimate rather than a printed value; internal target, tighter than the drawing's ±20%",
      "dispute_note": ""
    },
    {
      "node": "BC",
      "chart": 310,
      "sim": 312.887,
      "disputed": false,
      "dev_pct": 0.9312903225806453,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "preamp and phase-inverter feed, one printed 10 kΩ · 1 W dropper below the screen node — internal target",
      "dispute_note": ""
    },
    {
      "node": "PAY1",
      "chart": 175,
      "sim": 159.981,
      "disputed": false,
      "dev_pct": 8.582285714285717,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "Inst.-channel 12AY7 plate, 100 kΩ from +310 V",
      "dispute_note": ""
    },
    {
      "node": "PAY2",
      "chart": 175,
      "sim": 159.981,
      "disputed": false,
      "dev_pct": 8.582285714285717,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "Mic.-channel 12AY7 plate, 100 kΩ from +310 V",
      "dispute_note": ""
    },
    {
      "node": "KAY",
      "chart": 2.5,
      "sim": 2.508,
      "disputed": false,
      "dev_pct": 0.3200000000000003,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "shared 12AY7 cathode — both halves over one 820 Ω",
      "dispute_note": ""
    },
    {
      "node": "PPIA",
      "chart": 210,
      "sim": 204.151,
      "disputed": false,
      "dev_pct": 2.7852380952380904,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "phase-inverter plate, 82 kΩ · 5 % (hot) side",
      "dispute_note": ""
    },
    {
      "node": "PPIB",
      "chart": 200,
      "sim": 195.101,
      "disputed": false,
      "dev_pct": 2.4495000000000005,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "phase-inverter plate, 100 kΩ · 5 % (cold) side",
      "dispute_note": ""
    },
    {
      "node": "KPI",
      "chart": 27,
      "sim": 26.216,
      "disputed": false,
      "dev_pct": 2.9037037037036995,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "joined inverter cathodes, above the 470 Ω",
      "dispute_note": ""
    },
    {
      "node": "JPI",
      "chart": 25.5,
      "sim": 25.039,
      "disputed": false,
      "dev_pct": 1.8078431372548962,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "inverter tail junction (470 Ω / 10 kΩ), the return for both 1 MΩ grid leaks. '25.5' and '255' cannot be told apart on the low-resolution copy of this drawing; read unambiguously as +25.5 V at 777 ppi (see the sources cited on this page), which is also what the printed +27 V cathode one 470 Ω away requires",
      "dispute_note": ""
    },
    {
      "node": "G61",
      "chart": -27.5,
      "sim": -28,
      "disputed": false,
      "dev_pct": 1.8181818181818181,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V4 grid, fixed bias through a 220 kΩ leak from the −28 V line",
      "dispute_note": ""
    },
    {
      "node": "G62",
      "chart": -27.5,
      "sim": -28,
      "disputed": false,
      "dev_pct": 1.8181818181818181,
      "tol_pct": 20,
      "gated": true,
      "within": true,
      "note": "V5 grid, fixed bias through a 220 kΩ leak from the −28 V line",
      "dispute_note": ""
    },
    {
      "node": "NBIAS",
      "chart": -28,
      "sim": -28,
      "disputed": false,
      "dev_pct": 0,
      "tol_pct": 8,
      "gated": true,
      "within": true,
      "note": "bias line — solved through the drawing's own 82 kΩ / 56 kΩ divider off the printed −69 V, not abstracted. The joined 220 kΩ grid leaks and the Depth control's cold end sit here; no DC flows through the Depth pot — internal target",
      "dispute_note": ""
    },
    {
      "node": "SG1",
      "chart": null,
      "sim": 367.116,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "V4 screen, below the +368 V node through its own 470 Ω · 1 W. The drawing prints no screen voltage",
      "dispute_note": ""
    },
    {
      "node": "SG2",
      "chart": null,
      "sim": 367.116,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "V5 screen, below the +368 V node through its own 470 Ω · 1 W. The drawing prints no screen voltage",
      "dispute_note": ""
    },
    {
      "node": "GPIA",
      "chart": null,
      "sim": 25.039,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "phase-inverter hot grid — sits at the tail junction through its 1 MΩ leak. The drawing prints no voltage here",
      "dispute_note": ""
    },
    {
      "node": "GPIB",
      "chart": null,
      "sim": 25.039,
      "disputed": false,
      "dev_pct": null,
      "tol_pct": 5,
      "gated": false,
      "within": null,
      "note": "phase-inverter cold grid — the same, with the 0.1 µF · 200 V to ground beside it. The drawing prints no voltage here",
      "dispute_note": ""
    }
  ],
  "checks": [
    {
      "id": "dc",
      "title": "DC operating point",
      "status": "Within target",
      "summary": "12 reference nodes are within tolerance. The circuit remains a draft awaiting maintainer review.",
      "details": [
        "This compares simulated DC conditions with the cited reference. It does not test sound, physical construction or every part of the circuit."
      ],
      "tone": "checked"
    },
    {
      "id": "schematic",
      "title": "Schematic against DC model",
      "status": "Not checked",
      "summary": "No published check result is available.",
      "details": [],
      "tone": "neutral"
    },
    {
      "id": "board",
      "title": "Board against DC model",
      "status": "Not checked",
      "summary": "No published check result is available.",
      "details": [],
      "tone": "neutral"
    },
    {
      "id": "drawings",
      "title": "Schematic against board",
      "status": "No open findings",
      "summary": "No disagreement is listed in the published comparison.",
      "details": [
        "A finding identifies a difference or a coverage gap. The factory source must decide which drawing, if either, needs correction.",
        "2 sheet-only parts are explicitly excluded: RG1, RG2. Heaters and the pilot lamp are checked separately."
      ],
      "tone": "checked"
    },
    {
      "id": "heaters",
      "title": "Heater and filament wiring",
      "status": "Not established",
      "summary": "The drawn supply-leg connections have not been established by this check.",
      "details": [
        "Supply-leg grouping still needs confirmation at V1, V2, V3.",
        "V1: pins [4, 5] are one leg at 6.3 V and opposite legs at 12.6 V"
      ],
      "tone": "attention"
    },
    {
      "id": "polarity",
      "title": "Capacitor polarity",
      "status": "Partial",
      "summary": "1 capacitor marking cannot be confirmed by the DC model.",
      "details": [
        "CK3: CK3.a: reaches only ground, through RK3"
      ],
      "tone": "attention"
    }
  ],
  "corrections": [],
  "sourceDirectory": "https://github.com/TheAnalogMaker/circuit-codex/tree/195289eab0b0e41029bffd6e34b65f01a84e553b/amps/5g9"
}