HP LaserJet pro 400 series; solenoid won't energize.

[rev...@gmail.com]

Hello!
Solenoid is fine; not sticking and energizes with external source. Needless to say MP feed won't pickup paper. Also the printer spits out a single blank paper from Tray 2 whenever powered. Any ideas?

[Nife Sima]

On 26.02.2020 09:11, rev...@gmail.com wrote:
> Hello!
> Solenoid is fine; not sticking and energizes with external source. Needless to say MP feed won't pickup paper. Also the printer spits out a single blank paper from Tray 2 whenever powered. Any ideas?
>

Looks like it's confused about the paper sheet location, so to speak.

Check all limit switches and endstops (optical and mechanical)

[rev...@gmail.com]

Thank you for replying. Sensors seem to be okay. Also blank paper spitting is only at the time of powering on the printer, as if that makes any sense.

[peterw...@gmail.com]

I will guess that there is a sensor jammed/clogged such that it believes there is something in the pathway that it tries to reject - spits out a piece of paper. When that sensor does not clear, it shuts down. Have you cleaned the optical sensors? Either 91% Isopropyl alcohol and a very soft cloth, or distilled water and that same cloth.

Paper dust is is a very real issue, especially on heavily used copiers. Best of luck with it.

Peter Wieck
Melrose Park, PA

[rev...@gmail.com]

Thanks Wieck, for your insight. Optical sensors are clean, and no error code reported. Though MP feed solenoid won't energize thus no paper pickup from MP tray with error Tray 2 Jam error when print attempted with paper in Tray 1.

[Nife Sima]

On 26.02.2020 17:24, rev...@gmail.com wrote:
> Thanks Wieck, for your insight. Optical sensors are clean, and no error code reported. Though MP feed solenoid won't energize thus no paper pickup from MP tray with error Tray 2 Jam error when print attempted with paper in Tray 1.
>

If you get a Tray 2 jam error, and theres no paper jam, then the paper
jam sensors are faulty. Check these again with a multimeter if they are
mechanical, and clean the optical ones out throughly as Peter Wieck said

--
Nife Sima - the lower earth crust

[three_jeeps]

On Wednesday, February 26, 2020 at 11:24:09 AM UTC-5, rev...@gmail.com wrote:
> Thanks Wieck, for your insight. Optical sensors are clean, and no error code reported. Though MP feed solenoid won't energize thus no paper pickup from MP tray with error Tray 2 Jam error when print attempted with paper in Tray 1.

not sure how to parse the last sentence. Is there a period missing?
>Though MP feed solenoid won't energize thus no paper pickup from MP tray with error. Tray 2 Jam error when print attempted with paper in Tray 1.

If parsed this way, seems that cpu is confused about status/state of paper trays.....so check the tray sensors.
A HP service manual would be very helpful....do you have one?

[three_jeeps]

forgot to add: you say solenoid checks fine on external source...did you check the solenoid signal path?..Signal present but not getting through?

[rev...@gmail.com]

I do have the service manual. As for the signal path, any detailed advice on howto? Thank you for your kind help.