Technomaniac
Printing Apprentice
- Joined
- Jul 17, 2020
- Messages
- 3
- Reaction score
- 3
- Points
- 13
- Printer Model
- HP Deskjet 3325 C8949A
Hi. I have a neighbour who regularly gives me his old printers when they need ink or toner. So I have a collection!
I have been off-grid for more than five years, and using laser printers, which are economical to run, except for the power input. I've been starting up my diesel plant whenever I need to use the printer, and I use laptops, everything running from 24 volts DC normally. I have found starting the diesel inconvenient, so was thinking about a more power-economical printer. I considered Dot-matrix and inkjet. (Did you know that dot-matrix printers are still being made?) Anyway I settled on a HP Deskjet 3325 (The number on the bottom is C8949A). I de-shelved and cleaned out the cobwebs, gave the ink cartridges a polish-up and oilled the rod that the print gear slides on. Found a driver (or at least one that someone at HP reckons will work), and fired it up. It made lots of noises but no sign of printing.
The Win 10 wizard reckoned all was good. But after several sessions of trying, it suddenly dawned on me that it wasn't sucking in the paper !
I just about got my finger chopped off, (by the printhead flying past) while opening the lid, and I found the interlock switch defeating point, and I could see that although the easily visible paper-feed roller wasn't turning to pull the paper in, the gearwheel on the left-hand end of it was rotating quite solidly.
So I had a closer look at the centre of the gear, and found that the boss was split. I noticed a pulse-generating disc glued to the gear, and its outer edge is inserted into the gap of an optocoupler. This combination of parts produces electrical pulses to send to the computer to tell it how many lines of text or blank paper have been moved up.
So to take the wheel off to repair it (replacement parts for such gear an unknown quantity, but I did a search online, anyway), it was necessary to lift the whole mechanism, as the optocoupler was firmly mounted to the plastic cabinet bottom. Then I could slide the gear to the end of the shaft and OFF.
Naturally, since the gear had been rotating on the stationary shaft, the original spline inside the boss would have chewed out, so just making a sleeve to press over the boss would be inadequate as a cure. As I have lathes available, I machined up a couple of brass discs, to go either side of the original plastic wheel, and as there was, with the unmodified wheel fitted in place, about 5mm of the end of the shaft sticking out, one of the new brass discs has a boss right at the end of the shaft. And two allen-keyed grubscrews to key it to the shaft. Three countersunk metalthread screws hold the two brass discs with the original plastic one in between, as a sandwich, and which makes a very strong assembly. The inside disc had to be 1mm or less in thickness to prevent it from scraping other things. And the countersunk screws had to be carefully fitted so that they did not protrude at all. Then I made a little sleeve to push over the original plastic boss to close the split and give a little extra friction on the spline of the shaft. That end is sorted, but at the other end of the mech is a sliding tray that does something like clean the printheads. Under the tray is a rack, and there's a plastic shaft about 40mm long with two gears, one right at the end. That piece was laying in the bottom of the cabinet, and I'm not certain how to refit it. Also I'm in some doubt about the orientation of that sliding tray, as the rack underneath it has to engage with one of the gears on that little shaft. And whichever gear DOES have to engage, does not appear to be supported, which suggests that there should be something like a big plastic drawing-pin inserted into the hole in the end of the shaft to support it and keep it meshed.
So an exploded view from a spare parts manual might give me some answers. If explicit enough. Does anyone have one?
I have been off-grid for more than five years, and using laser printers, which are economical to run, except for the power input. I've been starting up my diesel plant whenever I need to use the printer, and I use laptops, everything running from 24 volts DC normally. I have found starting the diesel inconvenient, so was thinking about a more power-economical printer. I considered Dot-matrix and inkjet. (Did you know that dot-matrix printers are still being made?) Anyway I settled on a HP Deskjet 3325 (The number on the bottom is C8949A). I de-shelved and cleaned out the cobwebs, gave the ink cartridges a polish-up and oilled the rod that the print gear slides on. Found a driver (or at least one that someone at HP reckons will work), and fired it up. It made lots of noises but no sign of printing.
The Win 10 wizard reckoned all was good. But after several sessions of trying, it suddenly dawned on me that it wasn't sucking in the paper !
I just about got my finger chopped off, (by the printhead flying past) while opening the lid, and I found the interlock switch defeating point, and I could see that although the easily visible paper-feed roller wasn't turning to pull the paper in, the gearwheel on the left-hand end of it was rotating quite solidly.
So I had a closer look at the centre of the gear, and found that the boss was split. I noticed a pulse-generating disc glued to the gear, and its outer edge is inserted into the gap of an optocoupler. This combination of parts produces electrical pulses to send to the computer to tell it how many lines of text or blank paper have been moved up.
So to take the wheel off to repair it (replacement parts for such gear an unknown quantity, but I did a search online, anyway), it was necessary to lift the whole mechanism, as the optocoupler was firmly mounted to the plastic cabinet bottom. Then I could slide the gear to the end of the shaft and OFF.
Naturally, since the gear had been rotating on the stationary shaft, the original spline inside the boss would have chewed out, so just making a sleeve to press over the boss would be inadequate as a cure. As I have lathes available, I machined up a couple of brass discs, to go either side of the original plastic wheel, and as there was, with the unmodified wheel fitted in place, about 5mm of the end of the shaft sticking out, one of the new brass discs has a boss right at the end of the shaft. And two allen-keyed grubscrews to key it to the shaft. Three countersunk metalthread screws hold the two brass discs with the original plastic one in between, as a sandwich, and which makes a very strong assembly. The inside disc had to be 1mm or less in thickness to prevent it from scraping other things. And the countersunk screws had to be carefully fitted so that they did not protrude at all. Then I made a little sleeve to push over the original plastic boss to close the split and give a little extra friction on the spline of the shaft. That end is sorted, but at the other end of the mech is a sliding tray that does something like clean the printheads. Under the tray is a rack, and there's a plastic shaft about 40mm long with two gears, one right at the end. That piece was laying in the bottom of the cabinet, and I'm not certain how to refit it. Also I'm in some doubt about the orientation of that sliding tray, as the rack underneath it has to engage with one of the gears on that little shaft. And whichever gear DOES have to engage, does not appear to be supported, which suggests that there should be something like a big plastic drawing-pin inserted into the hole in the end of the shaft to support it and keep it meshed.
So an exploded view from a spare parts manual might give me some answers. If explicit enough. Does anyone have one?
