Colorspan 72UV vacuum pump problem

[SIGNMAN_52]

Our vacuum pump on this printer sounds like it is dying. It used to make an intermittent buzz which was the normal sound. Over the past 6 months or so the buzz sound has gotten longer and as of today it is making a constant buzz sound.
My hope is that I could trouble shoot it and find a cheaper solution using open market parts vs spending too much to get a replacement from HP.

Thanks for any help you can offer

 

[Mspec]

sounds like you have a leak that is getting worse. The pump only kicks in when the vacuum level drops below a setpoint ( usually around 4.8 inches ) if the pump runs all the time, it is probably trying to compensate for a leak.

Fold the vacuum line ( like a garden hose you want to stop the flow on ) just outside of the pump, if it starts to cycle on and off again like normal, you have a leak north of the pinched tube. Next pinch the vacuum tube at the manifold, then pinch off each tube from the manifold to each color. You should be able to chase down the leak like this. if the pump cycles when you pinch off the black tube, but not on the other three you have a leak on the black heads ( for example ) check all of the twist fittings on the carriage, if it is not a loose fitting, you may have a leak on a printhead.

 

[SIGNMAN_52]

Thanks for that advice. When I cut off the flow going up into the printer, there is no change. The pump is still running continuously. So the leak is somewhere at the pump. Any thoughts on how to isolate the leak at the pump?

 

[Mspec]

not much inside the pump itself. the vacuum switch ( large white cube with wires running in and out of it ) could have micro-welded contacts, causing the pump to run regardless of pressure. The test for that is easy, give the pump housing a rap or two with a screwdriver handle, if it stops the switch is toast. Next item would be the pressure regulator ( little grey guy with 2 or 3 little tubes on it. ) those can fail, but if you google the part numbers on it you can find an off the shelf replacement part. You also could have a bad seal on the big O ring inside the blue canister, screw that off, and smear a bead of grease or 3in1 oil on the Oring, then reinstall it.

Good luck.

 

[SIGNMAN_52]

After playing around with the pressure regulator I think that may be the culprit, so I have one on order (from a cheaper source than HP). Hopefully that will get us back in business.

 

[Mspec]

just be mindful of where the tubing connects to the regulator, the ports are marked 0,1, and 2. Ports 1 and 2 connect to the tubing in the "H" configuration, and the 0 port will be open, or have a filter installed on it. if it had a filter, but the fibers are no longer white, get a replacement. ( when the zero port filter clogs up it will affect the accuracy of the regulator, and cause the whole pump to read higher vacuum than what is really present. )