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Repair: Sanyo 20-EZ monitor

Another major colour 15 kHz chassis of US cabinets (~19-20″), very common — notably in Nintendo cabs (the 20-EZV variant with an audio board) and many US games. Standard CRT repair: HV discharge, recap (the 160 V caps first), plus two 20-EZ specifics: vertical collapse and board cracks.

Identification / variants

Chassis Note Typical use
20-EZ base colour 15 kHz chassis 1980s US games
20-EZV + integrated audio board Nintendo cabs (PlayChoice/VS…), revisions R-B / R-C
20-EZY variant per cabinet

Safety (read first)

High voltage — discharge the tube

Lethal high voltage held while unplugged → discharge the anode before work. See CRT safety & HV discharge. Isolation transformer for powered measurements.

The Sanyo 14″ (Atari TM-157) — another chassis, and it explains the isolation misunderstanding ✅

⚠️ \"The isolation transformer is not in the monitor — it is in the cabinet\"

The Sanyo 14″ Color TV Monitor — Operation, Maintenance and Service Manual (Atari TM-157, 1st printing, © 1980 Atari, monitor manufactured by Sanyo Electric Co., Ltd., Color TV Receiver Manufacturing Division, Gifu, Japan) ⚠️ is not this page's 20-EZ: it is an earlier 14″ chassis. But it sheds light on a question this wiki has been carrying for three days.

"If you service this color monitor on a test bench, you must isolate the monitor from AC line voltage! An isolation transformer is mandatory for your own safety. The Sanyo monitor does not contain an isolation transformer on its chassis. It is mounted instead on the game power supply. (It may appear like a regular power transformer, but is really also an isolation transformer.)"

✅ This is the explanation the seven-manufacturer table was missing. One monitor can be isolated in its cabinet and unisolated on the bench — not because the chassis changes, but because the transformer stayed behind in the cabinet. ⚠️ And you cannot spot it by eye: "it may appear like a regular power transformer".

ⓘ This contradicts none of the positions already published — the Sejoo isolated by its switch-mode supply, the Wells-Gardner whose chassis is tied to the mains, the Hantarex whose chassis is earthed. It adds a case: isolation provided by the cabinet, and lost the moment you take the monitor out of it. → CRT safety

Sanyo 14″ — data sheet, as printed
Item Value
Mains ⚠️ 100 V AC ± 10 %, 50/60 Hz — a Japanese-market monitor
Consumption 46 W
Monitor ambient 5 to 35 °C (41-95 °F), humidity 20 to 95 %
⚠️ Temperature inside the cabinet ⚠️ 45 °C maximum (112 °F)
Average anode current less than 650 µA
B+1 · B+2 105 ± 1.0 V · 19.5 ± 2.0 V
B+3 · B+4 (regulated) 12 ± 1.0 V · 175 ± 5.0 V
Heater 6.4 ± 0.2 V RMS
Tube #370ECB22, 14-inch, 90°
Yoke tilt declination within 2 mm
Convergence 0.2 % of raster width at centre · 0.5 % at corners
Pull-in range horizontal 15.75 kHz ± 200 Hz · vertical more than 8 Hz

⚠️ The in-cabinet temperature is a separate figure, and this wiki had it nowhere: 45 °C maximum inside the cabinet, distinct from the monitor's 35 °C ambient. ⓘ It is the one that matters when you close up a cabinet or add a board — a monitor within its limits can sit in a cabinet that is not.

Pinouts — 6-pin video connector: 1 = Red, 2 = Green, 3 = Blue, 4 = ground, 5 = sync. ⓘ That is the G07's order, and the reverse of the Sejoo "Vision". 3-pin power connector: pins 1 and 2 at 100 V AC.

ⓘ B+ is adjustable, but the manual reserves it: "B+ ADJUSTMENT (For Technicians Only)" — on resistor R609, in the centre rear area of the main board, marked "B+ ADJUSTMENT" on the circuit.

ⓘ Purity: "practically uniform all over screen after being degaussed with a hand-held degaussing coil" — the reference condition presupposes a manual degauss first.

The Sanyo EZV 19″ (Atari TM-311) — and what it reveals about Atari ✅

A third Sanyo, and it is not alone in meeting this spec sheet

This wiki now archives the Sanyo 19-Inch Color Raster Video Display — Atari TM-311, 1st printing, © 1987, with schematic and illustrated parts list.

Item What the manual writes
Mains ⚠️ 100 VAC, +10 % / −15 %, 47 to 63 Hz, 74 W max.
EHT 24 kV ± 1.5 kV
Average anode current < 650 µA
Scan 15.75 kHz ± 500 Hz · 60 Hz ± 5 Hz
Tube 510UTB22, 19″, 90°
Convergence centre 0.010″ (0.25 mm) · edges 0.020″ (0.5 mm)
Video 6 pins — G, R, B, ground, ground, ⚠️ negative composite sync

⚠️ It is a 100 V, Japanese-market set — like the 14″ above, and unlike the American 20-EZ.

ⓘ And it shares its spec sheet, line for line, with a Sharp monitor. The Sharp XM-2001N (Atari TM-304, same year) gives exactly the same values, down to the convergence tolerance — only the tube differs. ⓘ So this is not Sanyo's specification: it is Atari's, which two suppliers had to meet → Other CRT chassis.

Common faults

Symptom Likely cause Lead
Erratic brightness/deflection bad electrolytics, especially the 160 V ones Recap (160 V first)
Vertical collapse (a horizontal band) / partial collapse vertical deflection stage/IC, its caps Recap the vertical + check the vertical output IC
Intermittent dropouts / instability board cracks (the 20-EZ PCB cracks easily — hairline cracks across traces) Inspect under magnification, repair cut traces
B+ stuck low (e.g. ~30 V) regulation / supply Diagnose the +B / supply stage
Unstable horizontal sync H stage / joints Reflow, H diagnosis
Distorted / weak / no sound (20-EZV) audio board (bipolar caps, TR373 / TR374); JB/JC reversed → burnt resistors Audio recap + transistors; check the JB/JC connector orientation

Procedure — working through a chassis ✅

Discharge the anode before anything else

The tube holds its charge with the cabinet unplugged, and so does the main filter capacitor. Discharge it, keep one hand in your pocket, and do not work on it alone. → CRT safety

Hot chassis: the ground is not earth

Some arcade chassis are referenced to the mains. On those, chassis ground is not earth, and an earthed oscilloscope clipped to it makes a dead short through your probe. Work through an isolation transformer. → CRT safety

1. Cold, before switching on. Cracked solder joints are the fault on these chassis — around the connectors, the flyback and anything heavy enough to work its own joints loose. Also swollen capacitors, cooked resistors, the brown halo of something that has been running hot. Reflow what looks suspect before diagnosing: a good share of intermittent chassis faults end there.

2. Fuse and primary side. A fuse that goes again is a short downstream, not a fuse problem — find it before fitting another.

3. Is there EHT at all? The tick of the flyback at switch-on, the filament glowing in the neck. No EHT points at the supply or the line stage. EHT but no picture points at video or the G2 — two very different jobs, and this is the measurement that separates them.

4. Recap — before any adjustment. This page carries the capacitor list — take the one matching your exact chassis if it covers more than one. On a chassis of this age recap is not optional: the electrolytics are thirty years old and have been running hot since day one. → Recap

5. Adjustments, and only now. ⚠️ Never before the recap. Setting the geometry of a chassis whose capacitors are dying records the drift and makes you do the whole job twice. Write down where every pot was before you touch it. → CRT safety

6. Scan rate. This page covers several chassis with different capabilities — take the line for yours from its table. A board whose rate the chassis does not accept shows nothing, and nothing is faulty.

7. Verification. Let it run warm for a good while and check the geometry stops moving. A chassis that is right cold and wrong after twenty minutes is still a thermal fault — usually a joint, sometimes a capacitor you left in.

Repair (method)

  1. HV discharge → CRT safety.
  2. Recap (method) — start with the 160 V electrolytics (No. 1 cause of brightness/deflection). The main 470 µF / 250 V filter (the biggest cap) is often NOT in the kits → order it separately.
  3. Inspect the board: the 20-EZ PCB cracks (hairline cracks across traces) → repair the traces (traces & vias); handle the board gently (it is fragile).
  4. Vertical collapse: the vertical deflection stage (IC + caps).
  5. 20-EZV — audio board: a dedicated cap kit + TR373 / TR374; ⚠️ JB/JC must not be reversed (or resistors burn).

Cap kits & parts

Original documents archived ✅

  • PDF — sanyo-14-pouces-color-tv-monitor-atari-tm-157.pdf — Sanyo 14″ Color TV Monitor — Operation, Maintenance and Service Manual, Atari TM-157, 1st printing, © 1980 Atari Inc., Sunnyvale; monitor manufactured by Sanyo Electric Co., Ltd., Color TV Receiver Manufacturing Division, Gifu, Japan, 23 pp. ⚠️ This is not the 20-EZ — it is an earlier 14″ chassis, on 100 V AC. ✅ It is the one that explains that the isolation transformer is in the cabinet, not in the monitor. Harvested from Internet Archive's arcademanuals collection.

See also

Archived original documents ✅

Manufacturer documents archived locally, found in Internet Archive's arcademanuals collection on 14 August 2026 and identified from their title page. ⚠️ The items declare no licence — kept for preservation.

  • PDF — sanyo-20-ezv-rc-schematic-nintendo.pdf — 20-EZV (R-C) Schematic, revision 1, © 1982 Nintendo of America Inc., 4 sheets (sheet 1 of 2 and its reverse). ⚠️ Issued by Nintendo, not Sanyo: this is the document the distributor handed to its operators. It carries the picture tube socket board, the U885491 control circuit board, and a full legend of conventions — resistor types (insulated carbon film, metal film, metal oxide…) and capacitor types (ceramic, tantalum, mylar, polypropylene…). Via Internet Archive

Sources & attribution

  • Museum of the Game / Arcade-Museum — 20-EZ/20-EZV logs (160 V recap, vertical collapse, low B+, PCB cracks, audio TR373/374) — https://forums.arcade-museum.com/
  • arcadepartsandrepair / Paradise Arcade — 20-EZ/EZV cap kits (BOM cross-check, separate 470 µF filter) — https://www.arcadepartsandrepair.com/
  • Sanyo — 20-EZ service manual — to reference

Review & corrections

How this space is used

Spotted a wrong value, an outdated procedure, a chip reference that does not match your board? Say so here, with what you observed (model, board revision, serial number, measurement). Every report is cross-checked against a source before anything changes — an unverifiable correction is published as “reported by …, not cross-checked” rather than silently applied.

Reading is open to everyone; posting requires signing in with Discord. Reports from the wiki's declared reviewers are handled first; anyone else's are read too, but go through a human before anything is changed.