651C — Electronic Pressure Controller (MKS Instruments)

Name: 651C — Electronic Pressure Controller (MKS Instruments)
Brand: MKS Instruments
SKU: 651C
Price: 2144 USD
Availability: InStock

Part No. 651C

Market Price

→ Stable

$728–$4K

Typical secondary market pricing · USD

Low $728Avg $2,144High $3,560

Save 50-70% vs OEM new

Aggregated from secondary market sources · Not a guaranteed offer

Available by Request

Last verified: 2026-05-16

Request Quote · $728 – $4K

Talk to a specialist · parts@caladansemi.com

✓Tested & inspected

✓Documentation included

✓Fast worldwide shipping

✓30-day functional warranty

✓Escrow payment available

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How much does a used 651C — Electronic Pressure Controller (MKS Instruments) cost in 2026?

A used 651C — Electronic Pressure Controller (MKS Instruments) from MKS Instruments typically sells for $728 – $4k on the secondary market in 2026. That's a savings of 50-70% compared to new OEM pricing. Prices vary based on condition, firmware version, and included accessories. Request a quote for current availability.

Used MKS Instruments Parts & Consumables vs. buying new: is it worth it in 2026?

Used (2026)

✓Save 50-70% vs. new OEM

✓Lead time: 2-4 weeks

✓Condition: B grade

✓30-day functional warranty

New OEM

—Full OEM price (1–2.5× used)

—Lead times: 12–52 weeks

—New condition, full warranty

—Factory support included

Most buyers in 2026 choose used for cost and speed. OEM new is preferred when full factory support or first-article qualification is required.

What's included with a used 651C — Electronic Pressure Controller (MKS Instruments) from Caladan Semi?

Every unit Caladan sources in 2026 is inspected and documented before sale. Here's what you get:

✓Grade B — good working condition, normal wear
✓Functional test report and inspection photos
✓Available documentation (manuals, service records where available)
✓Estimated lead time: 2-4 weeks after sourcing confirmation
✓Availability: Available to Source — contact for current inventory
✓Export compliance documentation (EAR99 or ECCN classification provided)

How Much Does 651C Cost in 2026?

In 2026, used 651C controllers range from $728–$3,560, depending on condition and calibration history. Refurbished units with full traceable service (e.g., replaced PID boards, recalibrated sensors) start at $2,150, while non-refurbished used units (Grade B) begin at $728. New OEM pricing remains above $5,000, making used/refurbished models 50–70% cheaper. Units with >40,000 operational hours often exhibit sensor drift >15% and require immediate recalibration. Most buyers prioritize controllers with <20,000 hours and recent (2024–2026) calibration logs. Lead times for sourcing are 2–4 weeks, but units with missing 651C-01 analog modules add 1–2 weeks for part procurement.

651C Specifications and Compatible Tools

The 651C operates at 115V AC, 50–60Hz, with a ±0.5% setpoint accuracy across 0.01–100 Torr. It supports analog 0–5V or 4–20mA inputs and drives MKS 248A throttle valves or VAT 46.5 gate valves. Key compatible tools include Applied Materials Centura Etch (2000–2010 vintage), Lam Kiyo CVD (2005–2012), and HPS 300 series valves with 651C-02 interface boards. Warning: The 651C lacks digital communication; it will not integrate with tools requiring MKS 651D or 651E controllers for Ethernet/IP or Modbus. Always verify the presence of a 651C-01 analog board during inspection.

What to Check Before Buying a Used 651C in 2026

Vacuum seal integrity: Test with a helium leak detector; leaks >1×10⁻⁸ mbar·L/s invalidate the unit.
Response time: Apply a step input (e.g., 10 Torr to 50 Torr) and measure with an oscilloscope; acceptable response is <200ms.
PID stability: Compare factory-set gains (P=2.5, I=0.1, D=0.05) to current values using a multimeter; deviations >5% indicate sensor drift.
Board age: Inspect the 651C-01 PCB for capacitors >15 years old; replace electrolytics if >10 years post-manufacture.
Calibration history: Reject units without logs from 2023–2026; older calibrations correlate with >30% failure rates in 2026 field data.

Q: Is the 651C better than the 651D for Lam Kiyo CVD tools?
A: No. The 651D supports digital protocols required by Kiyo CVD models post-2008. The 651C works only with analog 248A valves (pre-2008 Kiyo).

**Q: How