Upgraded Solid State Relay (SSR) Board

Upgraded Solid State Relay (SSR) Board

Built-to-Order Upgrade for Harvest Right Freeze Dryers

The Upgraded SSR Board is a purpose-built replacement for the factory relay board used in Harvest Right freeze dryers, designed to eliminate the common failures associated with mechanical relay switching and poorly implemented AC control logic.

Each board is built to order, individually tested, and typically ships in under one week. Please allow adequate build time before shipment.

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Why Upgrade?

If you are experiencing repeated tray-heater relay failures, erratic heating behavior, or premature relay wear, the issue is not random—it is a design limitation of the factory relay system.

Harvest Right controls tray heaters using PWM (Pulse-Width Modulation) at 12 Hz, resulting in:

• 43,200 on/off cycles per hour
• Relays being turned off at peak AC voltage (~140V) instead of at zero-cross
• Severe contact pitting and early relay failure

Mechanical relays were never designed for this type of switching behavior.

This upgraded board replaces that failure-prone design with a properly engineered solid-state solution.

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What Makes This Board Different

True Solid-State AC Switching

• Uses a Triac-based SSR with Zero-Cross Detection
• Devices are turned on and off only when AC voltage crosses zero
• Eliminates arcing, contact pitting, and relay welding
• Dramatically increases reliability of tray heater control

No Unwanted Tray Heating

Most off-the-shelf SSRs include snubber circuits that allow leakage current, causing tray heaters to warm slightly even when “off.”

• This board intentionally does NOT use a snubber circuit
• Prevents phantom tray heating
• Designed specifically for resistive loads like tray heaters

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Board Design & Build Quality

• 2 oz copper PCB(not standard 1 oz)
  → Lower trace temperatures, higher current handling, improved longevity
• Oversized triac heatsink with proper thermal paste
  → Better heat transfer than factory SSRs
• Silicone wire strain bumpers under external connections
  → Prevents PCB cracking during installation
• Clearly labeled connections for:
  • Tray heaters
  • Compressor
  • Vacuum pump
    (Hot and Neutral properly marked — factory boards are not)

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Serviceability & Longevity

• Triac and relays are socketed and replaceable
• No soldering required for future repairs
• Low-cost replacement components
• Relays secured with tie-wraps to prevent vibration loosening
• Nylon mounting hardware with fixed standoff height
• Red LED indicators show when each device is powered
  → Tray LED visibly blinks at the 12 Hz PWM rate

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Installation Compatibility

• Fits directly into your existing Harvest Right relay board frame
• Ships with a 3D-printed mounting bracket(now standard)
• If your relay is not located behind the screen, an updated side-mount bracket is required:
  • 3D-printed
  • Includes 3M adhesive tape
  • Mounts cleanly next to the screen area

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Important Installation Notes

• Do not loosen the nylon mounting hardware
  (Height is pre-set and secured with thread locker)
• Ensure the green compressor ground wire is installed:
  • Between the tray and the securing nut
  • Closest to the compressor wiring connections

Proper grounding is critical.

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Key Benefits at a Glance

• Eliminates mechanical relay failures
• Proper zero-cross AC switching
• No tray heater leakage current
• Replaceable, serviceable components
• Cleaner wiring layout and labeling
• Built, tested, and supported by Donald

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Build & Testing

• Built to order
• Individually tested before shipment
• Typical build time: less than one week

Please be patient while your board is being assembled and tested.

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Important Notes

• Designed specifically for Harvest Right systems
• Installation is user-performed
• Improper wiring or grounding may cause damage
• If you require assistance, please schedule a one-on-one service appointment with Donald