ETA 7750-8062 Minute Counter Driving Wheel

Quantity	Discount (%)	Price
1 - 2	—	$6.00
3 - 4	5 %	$5.70
5 - 9	7 %	$5.58
10 - 14	10 %	$5.40
15+	15 %	$5.10

Quantity

Discount (%)

Price

1 - 2

—

$6.00

3 - 4

5 %

$5.70

5 - 9

7 %

$5.58

10 - 14

10 %

$5.40

15+

15 %

$5.10

Product Description

This is a genuine Swiss‑made ETA 7750.8062 minute counter driving wheel, a core transmission gear for the 30‑minute chronograph counter in the ETA/Valjoux 7750 automatic chronograph movement. Positioned between the chronograph seconds wheel and the minute counter wheel, this driving wheel transfers rotational motion at the proper reduction ratio to drive the 30‑minute chronograph hand at 12 o‘clock (or 3 o’clock, depending on the layout).

Features & Function

Genuine Quality: Factory‑produced by ETA Switzerland, brand new, fully compliant with original material and precision standards.

Compatible Movements: ETA/Valjoux 7750, 7751, 7753, 7754, and all 7750‑platform automatic chronograph calibers.

Part Number: ETA 7750.8062.

Function: This driving wheel transmits power from the chronograph seconds wheel to the minute counter wheel. When the chronograph is started, the seconds wheel rotates, driving this wheel one step per minute, advancing the 30‑minute counter hand one full revolution every 30 minutes.

Construction: Precision‑hobbed steel wheel with a pinion and a special driving finger. It engages intermittently with the finger on the chronograph seconds wheel to achieve one step per minute.

Repair Value: When the 30‑minute hand fails to advance, advances irregularly (jumps or stutters), misaligns after reset, or when periodic noises occur during chronograph operation, this wheel (worn teeth, deformed driving finger, or worn pivot) is often the cause – replacement with this genuine part is required.

Important Notes

⚠️ Genuine part identification: This is a genuine ETA original part (ref. 7750.8062). Counterfeit wheels have poor tooth geometry and hardness, leading to inaccurate timing or tooth breakage.

⚠️ Driving finger clearance adjustment: The ETA technical sheet specifies a clearance of approximately 0.02mm between the driving finger on the chronograph seconds wheel and the 7750.8062 driving wheel. Excessive clearance causes delayed minute hand start; insufficient clearance adds friction and affects timing accuracy. Use the eccentric screw for precise adjustment.

⚠️ Inspect the minute counter jumper spring: A weak jumper spring will cause the minute hand to jump or fail to lock in position. Always inspect the spring when replacing the driving wheel.

⚠️ Replace as a set: If the driving wheel shows tooth wear, the mating minute counter wheel and chronograph seconds wheel are likely also worn. Replace them together for full reliability.

⚠️ Single‑use: Once removed, do not reuse a driving wheel – always replace with a new part.

⚠️ Lubrication restriction: Oil only the pivot – keep all gear teeth absolutely dry. Oil attracts dirt and accelerates tooth wear.

FAQ

Q1: Is the ETA 7750.8062 driving wheel compatible with the 7753 caliber?
A: Yes. Although the 7753 has its 30‑minute counter at 3 o‘clock, it uses the same driving wheel as the 7750 (part no. 7750.8062). The internal construction and installation are identical.

Q2: How to tell if the driving wheel needs replacement?
A: Under 20x+ magnification, replace the wheel if the tooth tips show polished wear flats, burrs, or missing sections, if the driving finger is visibly deformed, or if the pivot has visible wear steps.

Q3: After replacing the driving wheel, the 30‑minute hand still does not move. What could be wrong?
A: Possible causes: ① damaged minute counter wheel; ② broken or weak minute counter jumper spring; ③ worn or deformed driving finger on the chronograph seconds wheel; ④ misaligned reset hammer. Inspect each component; replace the chronograph train as a set if needed.

Q4: How to precisely adjust the driving finger clearance?
A: Use the eccentric screw on the chronograph bridge for fine adjustment. Observe under magnification to achieve approximately 0.02mm clearance. You can also gently move the driving wheel with a wooden tool to feel the engagement tightness. Too tight adds friction; too loose causes delayed engagement.