Actuated desk - what goes up, must come down, but it wont

I would like some help on an issue I am having with my sit-stand desk. The crux of the issue is that the actuator will make the desk wind up, but will not let it wind down.

The actuator thing is made up of a few parts: the hexagonal shaft that turns a rack and pinion system in the desk leg; a cog with the shaft in the middle; a worm drive motor that interlocks with the teeth of the cog and turns the cog; the electronics.

The electronics consists of: 24v 4amp transformer; pcb board; switch (up and down); a switch that is only closed when the motor housing is closed; a top limit switch that is only open when the desk is at its highest; a bottom limit switch that is only open when the desk is at its lowest.

The switch works, in that, of the 4 wires that go to it, two are linked when neither up or down is pressed, the two linked wires are linked to another wire when up is pressed, and the other wire when down is pressed.

I removed the switch from the equation by twisting the three wires together that should be linked when down is pressed. It is just the PCB board that boggles my mind…it all works when moving the desk up, but wont work to move the desk down.

Please let me know what you would like me to post so as you can help me, if you kindly would.

Best regards.


[table] [tr][td]Power supply[/td] [td]vertex[/td] [td][/td][/tr] [tr][td]part number[/td] [td]AVL-000088-00[/td][/tr] [tr][td]model numer[/td] [td]662404000AT[/td][/tr] [tr][td]input[/td] [td]230v 50Hz 115W[/td][/tr] [tr][td]Output[/td] [td]24vac 4 A[/td] [td][/td][/tr] [tr][td][/td] [td][/td] [td][/td][/tr] [tr][td]Case[/td] [td]VL1, Series 2008[/td][/tr] [tr][td][/td] [td]Pro 1 / M1.25 / Stroke 460mm[/td][/tr] [tr][td][/td] [td]this motor must be used in conjunction with[/td][/tr] [tr][td][/td] [td]VL1, Series 2008 Actuator/Leg[/td][/tr] [tr][td][/td] [td]Serial nr: MD1110404009[/td][/tr] [tr][td][/td] [td]AVL-000092-00[/td][/tr] [tr][td][/td] [td][/td] [td][/td][/tr] [tr][td]Case brand?[/td] [td]Actiforce[/td] [td][/td][/tr] [tr][td][/td] [td]Xenonweg 11[/td][/tr] [tr][td][/td] [td]NL3812 SZ Amersfoort[/td][/tr] [tr][td][/td] [td]The Netherlands[/td][/tr] [tr][td][/td] [td]DMJ>P1[/td] [td][/td][/tr] [tr][td][/td] [td]24Vdc 90W Max 7A[/td][/tr] [tr][td][/td] [td]Class III[/td] [td][/td][/tr] [tr][td][/td] [td]Duty cycle 10%[/td][/tr] [tr][td][/td] [td]AVL-000048-01[/td][/tr] [/table]

Can you provide a few images of the setup so we better understand?















Thank you for your interest so far. I have posted a number of photographs. The outer of the motor case, the layout inside the case, the PCB board.

I can’t help but remember my high school electronics lessons…I am sure we had a program where we could draw up the circuit board and insert the components. If you put the right bits in the right places you could plan a PCB and test it in the software. I could likely replicate it on similar software. Is there anything like that freely available?

My other hope is that there a few first steps that I could do with my multi meter to identify the potential issue.

Apologies for my ignorance in this, i really haven’t been fiddling with electronics since school.

Unfortunately we do not carry any of these parts, so diagnosing them from a distance is not easy.
Our initial suspicion when you said it did not operate in a certain direction was because of the worm gear, though this does not seem to be the case.
Try connecting the leads directly to a battery to see if it works. You might need to purchase a new controller.


we had the same issue, only worked in one direction. The first thought was they used a wrong type of components (not working from the begining). Luckily, we had another one that works great in both direction, after excluding the mistype components (both have the same) I made some measures, and the cultprit was the T2 transistor and the D2 diode in the wrong one. I have a thought, the diode was short circuit from the begining, and killed the transistor also.

After I replaced this two components (and for the other direction also, T1 and D1 for be sure) works great.

These are the parts that you need:
2pcs BC639
2pcs 1N5817

Hope this helps.

Balázs Varga

Thank you very much for responding to my post. For mine the switch lead was a bit poorly soldered on to the pcb. My electrician friend bypassed the switch rj45 style port and soldered the switch wires directly to the pcb board for me. It is working perfectly now.

The help of Someone knowledgable in the use of of voltage meters helped a lot in my case. A lot of cake was their reward.


1 Like

I know this may be an old post… but are either of you able to help me please… I have this desk here in New Zealand and cannot seem to get it going to raise the level… I think there is a white missing that plugs into the back port… the white one… do you know where I can order a replacement wire so we can power it on? And what is the name of that part please?

@Kendra Welcome to the RobotShop Community. RobotShop does not sell motorized desks, so we can only potentially comment on the technology used, but without knowing the model or how it’s wired, there’s very little we can do to help. Have you reached out to the manufacturer with the model number, a description of the issue and photos?

Hey mate… Ive got the same motor… But the cables were all gone so ive made up the cable that links the 2 actuators… But not sure which pin needs to link to wich one… Can you please potentially send me a photo of yout wire colors and to wich pins they go or maby a wiring diagram?