Telebelt Receiver Fuses

The e-stop circuit of Telebelts includes the HBC 735 radio receiver.  Actually, the e-stop circuit supplies power to the radio receiver. 

The images below, A370160 Pg 4 and Pg 5 show the circuit. To view at a larger size, click on each photo individually and they will open in a new window.

The 12V supply (red) goes through the e-stop stations to X81 pin 13.  X-81 is located on the right-hand (hinge side) of the control cabinet.  The power then goes through a fuse in the radio receiver and returns to X81 pin 5, and then through the e-stop stations to 4A17, the e-stop relay. 

 

 

 

This image shows the pin locations on X81.

 

 

 

 

 

 

The image shows the inside of the 735 radio receiver.  There are 4 fuses called out in the image, and their reference numbers correspond to the reference numbers in the image that follows.

 

They are:

42 = Power supply primary – 6.3A

43 = Power supply secondary – 1.0A

44 = Proportional output card – 12.5A

45 = E-Stop card – 4A

 

 

All of these fuses remove by pushing the end cap in slightly and rotating it to the left.  When the cap releases, a spring pushes it out a little.  The fuse will be attached to the cap.  You might need a coin or flat blade screwdriver to remove the cap.

 

RULE #1 – The problem is NOT in the radio system

 

Symptoms of a problem:  

 

E-stop will not reset and there are no LED’s lit on the receiver.

 

FUSE FAILURES IN THE RECEIVER ARE RARE.  Make sure you check all the way through the e-stop circuit (SEE RULE #1).  A blown 4F17 or a bad e-stop button causes the same symptoms.

 

If you have no power at pin X81-13, the problem is NOT in the receiver.  If you have 12V at X81-13 and zero volts at X81-5, check fuses 42 and 43 in the receiver.  Either one of these fuses, when blown, cause these symptoms.

 

Before replacing any fuses and turning power back on, find the short.  Likely places are faulty e-stop buttons or their boxes, or cable shorts between X81 and the radio receiver.  The 90’ cable can be substituted for troubleshooting purposes.

 

E-stop will not reset and there are LED’s lit on the receiver.

 

SEE RULE #1.  There are many possibilities, including:

  • Remote switch problem.  Verify with cable remote
  • See control box schematic:
    • Blown 3F64
    • 4K69 or 3K275 bad or unseated – confirm by flashing 4A17-T33 to 4A17-T-34
    • 4A17 connections bad
    • 4A17 defective
  • Problem with receiver cable from X81 – use 90’ cable to confirm

 

If all else doesn’t correct the problem, check 4A fuse #45 on the e-stop card.  If the receiver cover is off, you will see the “light show,” but attempts to reset will just cause relays on the card to click.

 

E-stop will reset and there are LED’s lit on the receiver.  Only non-proportional functions (toggle switches) work, but moving joysticks only cause the WBV (Boom/Outrigger) selector valve to move.  The actual function levers do not move.

 

RULE #1 might not apply.  This is opposite from when the pilot valve relay is bad, or when you turn on the transmitter but don’t reset.  In that case, the function levers move but the WBV valve does not.   Just to be sure, use the cable remote to confirm the radio problem, then check the 12.5A fuse #44 on the proportional output card.

 

Before replacing any fuses and turning power back on, find the short.  Likely places are faulty cables or plug connectors on MBC valve, or cable shorts between X81 and the radio receiver.  The 90’ cable can be substituted for troubleshooting purposes.

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