Problems printing 2 sided with my HP Laserjet Pro 7740

[JP460]

Hi - I have a problem with my Laserjet Pro 7740.  It has been working fine printing 2 sided for ages.  Today it stopped doing that, if I asked for 2 sided it just printed one sided and every other page upside down so it was assuming I would manually feed the pages.  It was using a generic windows driver and when I went to the printer, properties and device settings no duplex unit option was shown.  I have tried deleting and re-adding the printer allowing windows to use its own drivers, and still I have the same problem (the firmware is fully up to date).  I have tried downloading the HP universal driver PCL6, and when I add this it does show the duplex unit as active and offer me the option the print double sided but whatever document i send to print I just get pages of garbage printed bearing no resemblence to reality.  Help please, how can I get a driver that works and also recognises this printer had a duplex unit and can print double sided as it always used to?

[Repairatrooper · Accepted solution]

The 7740 is not supported by the Universal Printer driver as that is a PCL6 or Post script driver and the 7740 uses a PCL3 driver. 

It is not listed as supported by the Smart Universal printer driver either, however it does support PCL3 so there is a remote chance that driver might solve your problem.  I suggest that you disconnect the printer, uninstall everything and then restart your PC. Then download the basic driver (link below) and reinstall. Start running the install and do not connect the printer until prompted to.   https://ftp.hp.com/pub/softlib/software13/printers/OJ7740/Basic_Webpack_x64-40.16.1234-OJ7740_Basicx...

[JP460]

Thank you!  Yes I noted the PCL 3 vs PCL 6 issue but I am completely ignorant about these protocols and a quick online search claimed PCL 6 was backward compatible with PCL 3 (AI always gives you a confident answer but that doesn't mean it should be confident).  This driver was exactly what I was looking for and works perfectly with the printer.  If I may ask one last question, I was previously using the windows HP Smart app with the printer, is it OK to reinstall this with the printer now installed with the basic driver or is that a bad idea as it may try to update the drivers and mess it up again?  Many many thanks again,

[Repairatrooper]

Should not interfere, but I have limited experience with the Smart App.