Wiggle My Legs Art.

Medical Lift Aid Repair

This project got underway in my spare time at the end of December 2020.  It is the Medical Lift, ChamberLift 2000, from Lift Aid, Inc., by Guido Capaldi.  This lift was provided by the Masonic organization Knights Templar.  To operate the lift there are three equivalent switches to operate depending on which switch is more convenient.  Two rockers that rock up and down and are at rest in the middle position while off.  Meaning normally off in the middle, and momentary-on when held up for lifting or held down for lowering.  These two rockers are located at the bottom of each of the two metal handles on either side of the hoist assembly.  The third switch is an optional, wired, handheld remote, that plugs into an RJ-11 type connector on this PCB.  The PCB, the RJ-11 connector and the other PCB components for user interaction are mounted to the metal bezel which has holes to allow the intended components to be offered to the user.

The symptom of the failure was when operating any of three switches to make the motor lift or lower, the spool apparently operates properly lifting, but is intermittent on down, or lowering.  So lifting can take a few seconds as is normal, and lowering can take many attempts over several minutes, rendering it mostly useless.  It seemed like voltage or capacitance build up, then failure of a component to either open or close, then the cycle repeats.  The battery charge level LEDs work, and the green charging LED works.  If you scroll down to the bottom here under Documentation, you can click on the component photo for C5 and see it was blown.  Since the first day of visual inspection I had wondered if this was the only problem and while determining specifications for several spare parts in addition to C5, and then waiting for the shipment, I worked on the schematic in Autodesk Eagle in case it was going to get difficult.

The C5 replacement arrived, and only having an analog Ohmmeter and a 9 Volt battery, I compared tests of the visually bad C5 to the replacement C5 and they looked the same every test.  I was flummoxed, and not being at the client site, I decided to keep looking for more obvious intermittencies in other components that I could prove.  I was thinking the failing component most likely would have to have a twin component, meaning one for lifting and one for lowering, and this category of components included C5.  In my spare time over many days, I removed and tested Power MOSFETs, transistors, resistors, and capacitors and found them all to be apparently good.  So over time, I made about three separate orders, each for a few more potential part replacements from digikey.com,  I finally made arrangements with the client to take my soldering tools to the client site and replace one component at a time until it worked.  When I set up at the client's site, the first component I replaced was C5 ...and VOILA!! ...it was fixed!  Now I'm shopping for a quality bench digital multimeter like possibly a Fluke, Klein, B&K, etc., that will give me the ability to measure Farads, a diode mode, and increased sensitivity.  It may prove pricey but will be a real time-saver.


Depiction of ChamberLift 2000 Lift Aid in use, done with lineart.

Close up of hoist housing showing metal frame in backgrouind.


Close up of hoist housing showing metal frame in backgrouind.

Showing the cloth belt that coils and uncoils from the hoist spool to raise and lower patient.


Showing the cloth belt that coils and uncoils from the hoist spool to raise and lower patient.

Close up of one of the two square tube handles that each have a rocker switch to lower and raise patient.


Close up of one of the two square tube handles that each have a rocker switch to lower and raise patient.

Photo of hoist assembly highlighting location of PCB control panel installed.


Photo of hoist assembly highlighting location of PCB control panel installed.

Photo showing hoist housing open and highlighting major components.


Photo showing hoist housing open and highlighting major components.

Photo showing front of PCB control panel assembly by itself removed from hoist assembly.


Photo showing PCB control panel by itself removed from hoist assembly.

Photo showing rear of PCB control panel assembly by itself removed from hoist assembly.


Photo showing PCB control panel by itself removed from hoist assembly.

Photo showing PCB component side with red circle around manufacturer AVID which is now AVNET.


Photo showing PCB component side with red circle around manufacturer AVID which is now AVNET.

22 second Video of repaired ChamberLift 2000 with a new C5 capacitor.  This is the same video posted to my Instagram account "@wigglemylegs" where you may also view other small projects.




300dpi photo of PCB solder side.


300dpi photo of PCB solder side.

300dpi photo of PCB component side.


300dpi photo of PCB component side.

Documentation

Here below is a link to download the 20-25 MB Excel spreadsheet of the BOM.  The downloaded Excel file arrives in "Protected View" so after downloading, if you want to view the photos in column 1, you must "Enable Editing" by clicking the "Enable Editing" button in the yellow notification banner, or under File / Options / Advanced.  If you prefer to keep the Excel file in "Protected View," the photos can be viewed in the browser using the direct links here below under "Original Component Photos."  The file is 20-25 MB because it contains about 51 photos.  Somehow the dimensions of the photo windows are not remaining set the way I set them.  The photos are inserted into the cell as a background fill pattern for a "Note" in the cell.  If the pictures are not completely visible, right-click the cell, select "Edit Note" (older Excel might show Edit Comment), you'll see a white box window for text that is blank and it has sizing handles.  Click and drag the sizing handles to reveal the missing part of the photo.  You'll see when you click the window sizing handle the white text box disappears revealing the photo.

Click this sentence to download the 20-25 MB Excel spreadsheet with photos (chamberlift2000_bom_pcb.xlsx).

Patient Lift Motor Control Schematic

Original Component Photos

Component_c1_330uf_25v_+85c_su_m   Component_c2_104   Component_c3_k5m   Component_c4_104_k5m   Component_c5_104   Component_c6_104_k5m   Component_c7_471_cog_63   Component_c8_471_cog_63   Component_c9_100uf_6pt3v_85c_su_m   Component_d1   Component_d2   Component_d3_6ai   Component_d4_p6ke20_gi_954   Component_d5_4001_616m   Component_d6   Component_d7   Component_d8   Component_d9_1n4148   Component_j1&j2&j3&j4   Component_q1_fec_56_k2049   Component_q2_2w_5q_irfz24n_i_r9609   Component_q3_2w_5q_irfz24n_i_r9609   Component_q4_fec_56_k2049   Component_q5_st9622_morocco_tip125   Component_q6_n624_2n4401   Component_q7_ztx_601_b   Component_q8_n612_2n4401   Component_q9_n624_2n4401   Component_q10_n624_2n4401   Component_r1   Component_r2   Component_r3   Component_r4   Component_r5   Component_r6_pot_f_b20k   Component_r7   Component_r8   Component_r9_0pt01_ohm_irc_lob3_9624_usa   Component_r10   Component_r11   Component_rn1_10x_1_271_b_9621_a   Component_rn2_l81s473_623_bi   Component_rn3_8x_1_103_b_9603   Component_rn4_10x_2_103_b_9624   Component_u1_dip_18pin_eprom   Component_u2_h_cd40109be_h_9514   Component_u4_m2954_03bt_9603_7496_thailand   Component_y1_4pt00ghz