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Top-tier supplier movement · caliber Tissot Cal. A05.H31: Valjoux 7753 base, Tissot-modified, 28,800bph, 42h PR; counters at 3, 6, and 9; used in PRX Chronograph · 42h power reserve
Medium-large: suits wrists 6.5 in+ (16.5 cm+)
42 mm case. Wears confidently on average to larger wrists. May overhang on slender builds.

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Authentication

Both pushers must depress and return cleanly; sticky pushers indicate a chronograph service is needed.

Known issues in the market
  • The Valjoux 7753 base with added column wheel produces a clean pusher feel; any sticking or partial return indicates a service requirement.
  • Pusher apertures at 2 and 4 must be clean with no gap between the pusher and the case.
AreaWhat to checkWhat is correctRed flag
casePusher depression and returnBoth pushers depress with a clean tactile click and return fully to the resting position without stickingAny pusher that sticks in the depressed position or returns sluggishly; indicates chronograph service needed
casePusher aperture fitPushers fit flush with no visible gap between the pusher body and case apertureVisible gap or play between pusher and case aperture indicating wear or incorrect pusher
braceletIntegrated PRX bracelet with chronograph caseIntegrated bracelet integrates flush with the chronograph case lugs; signed Tissot claspBracelet that does not sit flush with the case or unsigned clasp indicating aftermarket replacement
Common legitimate replacements
  • Column-wheel chronograph service on the modified Valjoux 7753 should be directed to a watchmaker with column-wheel experience.
Expert resources: Tissot PRX Chronograph documentation at tissotwatches.com. WatchUSeek Tissot subforum for column-wheel 7753 service notes.

Authentication guide

Last reviewed June 2026

The PRX Automatic Chronograph uses the Valjoux 7753 (Tissot reference A05.H31), with counters at 3, 6, and 9. It is a 42mm automatic chronograph in the integrated PRX bracelet. The extra case height (14.6mm) is expected given the 7753 architecture.

Known reproduction risks

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MEDIUM

The PRX Chronograph is replicated but less aggressively than the 3-hand 40mm version.

  • Sub-dial text poorly printed or wrong abbreviations
  • Integrated bracelet integration fails the same gap test as the 3-hand PRX
  • Chronograph hands do not align to 12 at reset

Dial variants by era

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EraDescriptionIdentifiers
2022 to presentBlue, black, or silver dial with three sub-dials at 3, 6, and 9 o'clock. 30-minute counter at 3, running seconds at 9, 12-hour counter at 6. Date window between 4 and 5.
  • Sub-dials should read "30 MIN" at 3, "12 H" at 6, small seconds at 9
  • "PRX CHRONOGRAPH" text on dial
  • Applied baton markers, no indices
  • Chronograph pushers at 2 and 4, case 42mm

Service part flags

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Pushers

Original: Round pushers with brushed finish at 2 and 4 o'clock. Push-to-start, push-to-stop, push-to-reset sequence.

Replacement tells
  • Slide-style or rectangular pushers are not correct
  • Pushers that screw down to lock are not original to this reference
Bracelet

Original: Same integrated PRX bracelet as the 3-hand version, sized for the 42mm chronograph case.

Replacement tells
  • Bracelet from the 40mm 3-hand will not fit; any mismatch at the lug is a red flag

Case back markings

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2022 to present
  • Screw-in caseback with Tissot medallion
  • Reference T137.427 prefix
  • "AUTOMATIC CHRONOGRAPH" marking
  • Serial and "SWISS MADE"

Movement tells

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  • The Valjoux 7753 beats at 28,800bph, noticeably faster than the Powermatic 80. If the movement sounds slow on this reference, the wrong caliber is inside.
  • The chronograph should start and stop cleanly with no bounce or column-wheel hesitation. Spongy action indicates worn detent springs or a column-wheel that needs service.
  • Power reserve is 42 hours. A fresh service should restore full 42-hour runtime.
Sources: Tissot PRX Chronograph official page; Fratello: Tissot PRX Automatic Chronograph Review.

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