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Post by Deleted on Jun 25, 2012 21:02:34 GMT
My printer, I think, was subject to a mains spike, it and a couple of smaller devices (e.g. bedside clock) were affected. From being off but plugged in, I came back to it having a blank lit display. It would not respond to any keypress including power. I unplugged, let it be for an hour or so and then tried a power up, nothing, except a buzzing from the psu. I removed the psu and looked for bulged caps or charring but nothing was evident visually. The unit still outputs the correct voltages on the meter (still buzzing) but the printer remains dead if re-inserted. Is there a fix for these, maybe a typical fault? more piccys!Any help greatfully received. Thanks
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XTRProf
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Post by XTRProf on Jun 26, 2012 2:04:10 GMT
The unit still outputs the correct voltages on the meter (still buzzing) but the printer remains dead if re-inserted. If it still output the correct voltages, it's not the PSU already. How about the printer control PCBA to start with. I have no clue how to fix the printer circuit board as it should be SMD, I think. Anyway, inkjet printer is very cheap. So go buy another new one if fixing it cost almost the same at the service centre.
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Post by Deleted on Jun 26, 2012 6:39:03 GMT
Feed the printer with a separate DC power supply (try 24V) or 'load' the power supply and see if it still provides power. It might go in an overload mode and still periodically charge the output caps giving the apearance it works, but doesn't under load.
The buzzing certainly is not normal but some power supplies need a minimal load and behave this way when not loaded.
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Post by Deleted on Jun 26, 2012 7:30:29 GMT
I agree with Frans. You need to try it with a dummy load. I have had Router SMPS that read correct output with no load, but fail under load. Anyone who is into serious DIY really needs a bench supply capable of at least +-20V at 1A, although that may not be high enough current for some devices, you may be able to get say +-12V at up to 2A from some, and ignore the earth terminal (centre tap).I used to supply a small 50V soldering iron that way. Alex
P.S. Frans Perhaps a good, but cheap, bench PSU could be a good future RG project, especially as you can get DMM modules for not much more than $20 ?
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Post by Deleted on Jun 26, 2012 11:19:48 GMT
Thanks for the responses.
Any suggestions on the dummy load, bearing in mind the 31v and 1.4A x2 capacity? (The psu buzzes whether in the printer or on the bench)
If the psu can be confirmed as faulty I've tracked down some cheap sources for replacement. If the fault lies in the printer itself then that's a different ball game.
The printer, a 3 in 1, is not a cheapie, so replacing the whole thing is not desirable.
Cheers.
ps I'd be up for bench psu project. I know there are loads on the net but most are either too high brow or are based on old PC psu's allowing only several fixed voltages.
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Post by Deleted on Jun 26, 2012 11:59:18 GMT
Hi Chris I can't think of a suitable dummyload for that high a voltage. You say that the PSU buzzes even when on the bench. Did it buzz originally ? SC has designed a new bench PSU but it is far more complex than the earloer one.The 1st part of the article appears in the U.K. magazine Everyday Practical Electronics for June 2012, but there is no mention of a kit .It looks like only Altronics did this kit in Australia. The main PCB, front panel and LCD meter are available from E.P.E. for about 25 GBP. The original E.A. Bench PSU used a moving coil meter for measuring the output voltage, but I fitted a LED DPM to mine years ago. A LCD DPM would also do a good job there as in the new version. Alex Attachments:
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Post by gommer on Jun 26, 2012 12:51:13 GMT
a cheap dummy load is a length of resistor wire in the form of welding wire. experiment, measure and calculate the appropriate length. Count on roughly 1 ohm per meter, 1 wire is probably good for a few amperes.
Cheers, Marc
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Post by Deleted on Jun 26, 2012 14:43:01 GMT
3x 12V (20W) halogen bulb in series or perhaps even 2 in series will do the job. Also you can use something like a 230V heater (or appliance) that draws between 1000W and 2000W. This should give an appropriate load.
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Post by Deleted on Jun 26, 2012 22:06:50 GMT
3x 12V (20W) halogen bulb in series or perhaps even 2 in series will do the job. Aha, I have some of those lying around somewhere, I'll give that whirl. Thanks Frans.
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Post by Deleted on Jun 27, 2012 12:21:59 GMT
Frans, I hooked up the 3x12v/20w halogens last night, all lit and the voltage output showed a 0.2v drop on that load. The "Vp" and "Vm" performed indentically. The buzzing also reduced to nearly inaudible. So I guess it's the main board in the printer itself, damn it! I'll dismantle to see if there is anything obvious, otherwise it's a new machine Alex, Thanks for the pointer on the bench supply, looks interesting. Cheers
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joethearachnid
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Post by joethearachnid on Jun 28, 2012 21:34:39 GMT
Just figured that I'd pop in and mention that I'd be quite interested in a project for a (low-noise?) bench PSU for testing and other applications.
-JoetheArachnid
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Post by Deleted on Jun 28, 2012 21:46:02 GMT
Just figured that I'd pop in and mention that I'd be quite interested in a project for a (low-noise?) bench PSU for testing and other applications. -JoetheArachnid Hi Joe I will send you some info about the one currently being published in Everyday Practical Electronics June 2012 issue. In Australia it is available as a kit from Altronics, but the basic parts like main PCB , front panel and DPM are available from E.P.E. at a very reasonable price for those in the U.K. etc. Regards Alex
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XTRProf
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Post by XTRProf on Jun 29, 2012 2:43:03 GMT
I will send you some info about the one currently being published in Everyday Practical Electronics June 2012 issue. In Australia it is available as a kit from Altronics, but the basic parts like main PCB , front panel and DPM are available from E.P.E. at a very reasonable price for those in the U.K. etc. Btw, that can go until what voltage and amp? I'll be interested if higher voltage and amp. Thanks.
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Post by Deleted on Jun 29, 2012 3:29:20 GMT
I will send you some info about the one currently being published in Everyday Practical Electronics June 2012 issue. In Australia it is available as a kit from Altronics, but the basic parts like main PCB , front panel and DPM are available from E.P.E. at a very reasonable price for those in the U.K. etc. Btw, that can go until what voltage and amp? I'll be interested if higher voltage and amp. Thanks. It's rated as up to +-19V at up to +- 1.6A. P.M. sent. Alex
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Post by Deleted on Jun 29, 2012 18:42:01 GMT
Just to give my first post above closure; I pulled the 3-in-1 apart last night, the amount of dismantling required to get to the vitals was incredible! I was on the lounge floor with all the panels, brackets, blah blah all around me in some sort of order, even my sons eyes popped out when he saw the extent of the disassembly. Finally managed to get to guts, the control board and UI board. Both had power coming in but nothing after any regulating stages and there were over heating signs around the main chips, all SMT of course. Googled for the boards today and £ £ Stuff that, nipped out and bought a cheapie instead, it plus inks was cheaper than just one board, no brainer really.
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XTRProf
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Post by XTRProf on Jul 2, 2012 3:06:21 GMT
So working after the cheapie nipped PCBA arrived and put in?
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Post by Deleted on Jul 2, 2012 5:22:10 GMT
Chong Chris is saying that he has written off the old printer and replaced it with a cheap model complete with inks. Alex
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XTRProf
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Post by XTRProf on Jul 3, 2012 0:46:49 GMT
Sorry fast reading misinterpretation. Thanks Alex for the clear up ...............
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