Right, having cleaned the printer, which had leaked ink (see other post) and cleaned the work area I am trying to get it working again.

I have an old iMac running macOS 10.6.8 Snow Leopard and the aforementioned HP DeskJet 840C printer. I print “wirelessly” from a more modern iMac under Catalina v10.15.3 (19D76) to the Snow Leopard machine which is connected to the printer via a USB cable.

On a previous old iMac this arrangement worked just fine using one of the Gutenberg drivers (I think) but, alas, i cannot remember which version. I no longer own that iMac but I do still have access to it should that be the way forward,

I have now connected another old iMac to the network and, when I tried to print, it returned the advice that there were no drivers and that the automated search of Apple found none. This is what I expected, of course.

I then went to Gutenberg and downloaded usbtb-1.0.17.uni.dmg as advised on the Mac paragraph and installed the driver.

Both iMacs can now see the printer but when I print a test page from either of them I get one page showing:

% I PS-Adobe-3.0 % APL_DCS_Encoding: UTF8 % APLProducer: (Version 10.6.8 (Build 10K549 …

The text runs across the A4 Portrait page but at each % symbol the text drops down a line. There may be further text after the Build number but it would be off the paper.

The submitted test page fails to print and the printer just spews out blank pages ad nauseam until I turn off the printer, seemingly the only way to stop it.

Am I using the correct driver from Gutenberg?

Is there any thing I can copy off the other iMac which did work and, if so, just what and where would I find it?

Is there another source of drivers which would solve my problem?

If you can offer any advice I would be most grateful.

Thanks in advance.

Try downloading the driver from HP drivers download instead of the GutenPrint drivers and see if that doesn't solve your problem. Although they do not have a Snow Leopard specific driver either the Tiger (OS X 10.4) driver should work. If not try the Lion (OS X 10.7) version.

Thanks. I note that they have drivers for the 940C series but not the 840C, but I'll download the dmg to which you pointed and try to get it to work over the next few days.

I shall report back the results in due course.

Thanks for the advice.

HP has no mention of an HP Deskjet 840C on their website — even among the no longer supported printers. In fact they do not even mention the 800 series. However, Cnet has a driver for download that reputedly supports the HP 800 series and looks like it would be worth trying.

Thanks to DEVONagent pro I found another site Life Support Association.org that archives drivers and other software for older PCs and Macs including these drivers for the HP Deskjet 840C. Hope this helps.

As, according to their website, HP clearly never made any DeskJet 840C colour
printers I must have manufactured my own whilst under the influence of some legal, or possibly illegal, mood modifiers. Or both together, of course.

No wonder getting a driver for a non-existent printer is so difficult!

But I have, in part, succeeded. And the part that hasn't [yet] succeeded? I can at the moment only print in black and white as the colour cartridge doesn't seem to be getting the message, but that's a problem for resolution later as at least I can print something now.

I can now print from both the Snow Leopard and Catalina iMacs using the driver OSXHPInkjetInstaller from the HP940 series of printers at https://support.hp.com/us-en/drivers/selfservice/HP-Deskjet-940c-Printer-series/35985 and selecting to MacOSX 10.4 version.

Mind you, as seemingly the only person in the world to have a DeskJet 840C, at least according to the experts at HP, this information won't help anyone else - unless you too made your own 840C printer without realising it!

Thanks for the advice, one and all, yet again FineTunedMac comes up with the goods!

Well, I now have to revise my last post!

As I mentioned, I could print but only in black and white. I checked the brand new colour cartridge and also replaced it - still black and white only.

I decided to go back and start all over again. I deleted all the various drivers which I had tried using AppCleaner to ensure that if there were any odd associated files lying around they would be deleted as well.

I then had a thinking session, a rarity with me according to my nearest and dearest.

I was pretty sure that, on the other old Snow Leopard iMac mentioned in the OP, I had installed a driver from Gutenberg so I went back there and again downloaded usbtb-1.0.17.uni.dmg and installed that.

Maybe I didn't look around hard enough or maybe I just overlooked the vital step, but I found the HP DeskJet 840C driver option, selected that and I am now printing in colour again!

OK, here's what I did this time around for anyone else having the same, or perhaps similar, problem.

Download usbtb-1.0.17.uni.dmg from Gutenberg on this page. using the signpost information on this page. this page.

Install it and then find the correct driver, in my case HP DeskJet 840C - Gutenberg 5.2.3. Follow this path:

System preferences > Print and Fax > Options and supplies > Driver > Print Using > HP DeskJet 840C - Gutenberg 5.2.3

And that did it. Apologies if my post immediately above misled anyone but, as HP have seemingly never made the 840C according to their current and unsupported printers, I think the chances are slim!

Good solve and thanks for getting back to us with it. 👏