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Tim R <timothy42b@aol.com>: Jul 29 07:26PM -0700 I run the headphone jack of the PC we use for internet into a Yamaha AV amplifier and a set of stereo speakers. It's not an audiophile system but it's much better than PC speakers.   It would be really convenient to stand the amp vertically to save desk space. But it has vents top and bottom, none on the front back or sides.   Can you run these vertically? or do they need the airflow from the bottom to stay cool enough?

jurb6006@gmail.com: Jul 29 08:24PM -0700 If you are going to really push the thing, a fan would be a good idea.   I had a Pioneer SA-1270 on the floor u on its side running into 2.3 ohms, and cranked quite often. Without the fan, which was a breeze box type, it would start smelling like an overheated iron. I am surprised it survived.   If you are running into eight ohms you probably don't have to worry.   At the very worst you'll have to get one of those little muffin fans and tape it or whatever to the top, the circulation it induces should be as good as the convection the amp was designed for.   Run it a while and feel it, if it is hot get a fan.

N_Cook <diverse@tcp.co.uk>: Jul 30 09:01AM +0100 On 30/07/2017 03:26, Tim R wrote: > I run the headphone jack of the PC we use for internet into a Yamaha AV amplifier and a set of stereo speakers. It's not an audiophile system but it's much better than PC speakers.   > It would be really convenient to stand the amp vertically to save desk space. But it has vents top and bottom, none on the front back or sides.   > Can you run these vertically? or do they need the airflow from the bottom to stay cool enough?   Could you remove the top cover of the amp , cut a hole in the side that would become the new top face and cover that with a fan grille or similar mesh? A matching lower hole would not be required, assuming there will be airflow into the original air vants

Robert Roland <fake@ddress.no>: Jul 29 08:02PM +0200 >D1,4 test as short cct.   I would take those out and check outside the circuit.   If the short is at the output of the bridge rectifier, and all four diodes are good, you should measure a diode drop (0.6 V or so) across the diodes in both directions. -- RoRo

"Dave M" <dgminala@mediacombb.net>: Jul 29 01:17PM -0500 Replace the shorted recctifiers!!!! As a precaution, replace all 4 of them; they're cheap. Even in circuit, they should not test as a short corcuit.   Cheers, Dave M       T i m wrote:

tabbypurr@gmail.com: Jul 29 11:49AM -0700 On Saturday, 29 July 2017 19:03:01 UTC+1, Robert Roland wrote:   > If the short is at the output of the bridge rectifier, and all four > diodes are good, you should measure a diode drop (0.6 V or so) across > the diodes in both directions.   if you test individually: 0.6v one way only if testing at bridge input: 1.2v both ways   An easy way to find faults is to run the psu via a filament light bulb, then it's easy to probe the [dangerously live] circuit for voltages with due care. Since I don't know if you can do this safely, don't do it.     NT

T i m <news@spaced.me.uk>: Jul 29 08:29PM +0100 On Sat, 29 Jul 2017 13:17:05 -0500, "Dave M" <dgminala@mediacombb.net> wrote:   >Replace the shorted recctifiers!!!! As a precaution, replace all 4 of them; >they're cheap. Even in circuit, they should not test as a short corcuit.   <snip>   Thanks Robert / Dave,   I haven't played much with SMPS (for obvious (safety) reasons) so assumed there might be some strange 'appears short but isn't in use' type thing going on. I should have pulled those diodes before asking here. ;-(   However, I just desoldered one end of both and one appears to be dead short but the other was ok (but I've pulled them all).   Problem is, while I probably have 1,000 IN4004's, I don't have any 1N4007's and I'm guessing we need the 1000V peak reverse / DC blocking voltage (rather than just 400) and 700 over 280V RMS? ;-(   So, I can pick some of those up next week (eBay) or it looks like Maplin have 1N4007S's in stock but are they an acceptable equivalent? (Peak forward surge current, 30 not 50A)?   http://pdf1.alldatasheet.com/datasheet-pdf/view/329384/CHENG-YI/IN4004.html   http://www.mouser.com/ds/2/395/1N4001S%20SERIES_F15-1082941.pdf   Cheers, T i m   p.s. How long is a piece of string question but ... Is it 'likely' that diode just went (the charger is a good few years old now and has been used quite a bit), or is it more likely something further down the line took it out?

T i m <news@spaced.me.uk>: Jul 29 08:38PM +0100 >> diodes are good, you should measure a diode drop (0.6 V or so) across >> the diodes in both directions.   >if you test individually: 0.6v one way only   Yeah, my diode test function was showing around 520mV on the good ones.   >if testing at bridge input: 1.2v both ways   Understood.   >An easy way to find faults is to run the psu via a filament light bulb,   I did remember that earlier and was going to rig up a plug - lamp -socket jig to make it easier. I thought I'd better ask here first. ;-)   >then it's easy to probe the [dangerously live] circuit for voltages with due care.   Understood.   >Since I don't know if you can do this safely, don't do it.   Understood. Whilst I have co-designed and scratch built plenty of mains powered kit (including disco sound-to-light, sequencers and strobes) I prefer not to be playing with live kit unless it's the only way (or the kit is very well mounted and otherwise insulated / protected, not just loose on the bench etc).   Cheers, T i m

"tom" <tmiller11147@verizon.net>: Jul 29 03:54PM -0400 "T i m" <news@spaced.me.uk> wrote in message news:h9npnct8gjd7pmoh3e9m6g7sh8rvm06721@4ax.com... > that diode just went (the charger is a good few years old now and has > been used quite a bit), or is it more likely something further down > the line took it out?   It is likely that the off line switch regulator is also failed. Grab a copy of the TOP223Y datasheet to see the reference design for your supply.   Here is a source for those chips:   http://www.ebay.com/itm/5PCS-TOP223Y-Encapsulation-TO-220-Three-terminal-Off-line-PWM-Switch-/371080857393?hash=item5666248731:g:h~8AAOSwnLdWrEJR

"Dave M" <dgminala@mediacombb.net>: Jul 29 02:59PM -0500 Yes, the 1N4007 recrifiers should be good replacements. Likely to be the only problem in your unit.   As a precaution, you should check the large transistors on the board. They are likely to be high voltage MOSFETs, and should NOT be shorted or low resistance from drain to source or from gate to any other terminal. Best to take them off the board to test, since they're certain to be connected to the low resistance transformer windings, which could lead you astray.   Cheers, Dave M   T i m wrote:

"tom" <tmiller11147@verizon.net>: Jul 29 04:02PM -0400 Dave,   The "large transistors" are TOP223Y off line switching regulator ICs. Google the part number for the datasheet and reference design.   Regards       "Dave M" <dgminala@mediacombb.net> wrote in message news:1KmdnWTYV6-adOHEnZ2dnUU7-THNnZ2d@giganews.com...

T i m <news@spaced.me.uk>: Jul 29 09:14PM +0100 On Sat, 29 Jul 2017 15:54:33 -0400, "tom" <tmiller11147@verizon.net> wrote:   <snip>   >> been used quite a bit), or is it more likely something further down >> the line took it out?   >It is likely that the off line switch regulator is also failed.   There are two in this PSU so could that apply to one or both?   > Grab a copy >of the TOP223Y datasheet to see the reference design for your supply.   I have looked at this:   https://www.digchip.com/datasheets/parts/datasheet/373/TOP223Y-pdf.php   ... and see roughly how it would work but not sure if that means I should be able to test it somehow? FWIW, I have one of the little component testers but I don't know if it will know what that is or even damage it?   >Here is a source for those chips:   >http://www.ebay.com/itm/5PCS-TOP223Y-Encapsulation-TO-220-Three-terminal-Off-line-PWM-Switch-/371080857393?hash=item5666248731:g:h~8AAOSwnLdWrEJR   Thanks for that. However I am in the UK and but get them here also. ;-)   Cheers, T i m

T i m <news@spaced.me.uk>: Jul 29 09:22PM +0100 On Sat, 29 Jul 2017 16:02:34 -0400, "tom" <tmiller11147@verizon.net> wrote:   >Dave,   >The "large transistors" are TOP223Y off line switching regulator ICs. Google >the part number for the datasheet and reference design.   Would you think one of those component testers would be able to identify the PWM reg, at least with a go/no-go result?   From testing around there were no shorts around the devices but that doesn't stop them being OC or just non-functional?   Cheers, T i m

"tom" <tmiller11147@verizon.net>: Jul 29 04:23PM -0400 "T i m" <news@spaced.me.uk> wrote in message news:2nqpnct2pd9g7dna6m64vudnfotf5k1t9h@4ax.com...   > Thanks for that. However I am in the UK and but get them here also. > ;-)   > Cheers, T i m   A quick ohmmeter check across the three pins should not show a short circuit.   If it does so in circuit, you may need to remove the device to check.

"tom" <tmiller11147@verizon.net>: Jul 29 04:32PM -0400 "T i m" <news@spaced.me.uk> wrote in message news:2nqpnct2pd9g7dna6m64vudnfotf5k1t9h@4ax.com...   > Thanks for that. However I am in the UK and but get them here also. > ;-)   > Cheers, T i m   Look at fig 8 in the datasheet for how your unit works. If I read your post right, this charges LiIon batteries, right? So the outputs should be about 4.0 to 4.2 volts. There is some feedback coming from the battery that probably looks at the battery temperature for a safety shutdown.   You could probably reverse engineer the whole schematic (or half of it) to get a better view of what is going on.   BTW, the transformer on the right next to the capacitor is not a transformer. It is a common mode choke for RFI filtering.

T i m <news@spaced.me.uk>: Jul 29 09:57PM +0100 On Sat, 29 Jul 2017 16:32:22 -0400, "tom" <tmiller11147@verizon.net> wrote:   <snip>   >> should be able to test it somehow? FWIW, I have one of the little >> component testers but I don't know if it will know what that is or >> even damage it?   <snip>   >Look at fig 8 in the datasheet for how your unit works.   OK. Again, I get the rough idea but I was more into digital electronics than SMPSU etc.   >If I read your post >right, this charges LiIon batteries, right?   Sorry, no, it's a general purpose multi-cell NiCad / NiMh charger Tom.   http://www.conrad.com/medias/global/ce/2000_2999/2500/2500/2503/250363_RB_00_FB.EPS_1000.jpg http://www.ansmann.de/en/service/downloads/send/6-bedienungsanleitungen-aelterer-produkte/66-5207123-energy-16   <snip>   The PSU board feeds a fairly complex logic / output board (4 PSU outputs to the logic board) and in turn the 16 charger outputs.   >You could probably reverse engineer the whole schematic (or half of it) to >get a better view of what is going on.   Ok.   >BTW, the transformer on the right next to the capacitor is not a >transformer. It is a common mode choke for RFI filtering.   Ah, ok, thanks ... that (now) makes more sense as even with that (choke) in and D1-4 out, I've lost the short I was seeing across the mains input. ;-)   Cheers, T i m

"tom" <tmiller11147@verizon.net>: Jul 29 05:17PM -0400 "T i m" <news@spaced.me.uk> wrote in message news:respncdm39h95fhbhrnaukpaaet7f92nbb@4ax.com... > (choke) in and D1-4 out, I've lost the short I was seeing across the > mains input. ;-)   > Cheers, T i m   Ok, good. That makes more sense for why so many outputs.   Doing any measurements on this device (scope, etc) will require an isolation transformer to look at the primary (line) side. The outputs all appear to be isolated.   Hope it's just the shorted diodes.   Good luck.   Regards

tabbypurr@gmail.com: Jul 29 02:27PM -0700 On Saturday, 29 July 2017 20:59:12 UTC+1, Dave M wrote: > the low resistance transformer windings, which could lead you astray.   > Cheers, > Dave M   I've been led astray by small amounts of capacitance before     NT

T i m <news@spaced.me.uk>: Jul 29 10:38PM +0100 On Sat, 29 Jul 2017 17:17:26 -0400, "tom" <tmiller11147@verizon.net> wrote:   <snip>   >> (choke) in and D1-4 out, I've lost the short I was seeing across the >> mains input. ;-)   >Ok, good. That makes more sense for why so many outputs.   It's quite an expensive unit (I think it cost me ~100 UKP some years ago) so I'd like to get it going if I can.   >Doing any measurements on this device (scope, etc) will require an isolation >transformer to look at the primary (line) side.   Understood.   >The outputs all appear to be >isolated.   Ok.   >Hope it's just the shorted diodes.   Fingers crossed. ;-)   >Good luck.   Thanks for your help and I'll let you know how I get on.   Cheers, T i m

tabbypurr@gmail.com: Jul 29 02:45PM -0700 On Saturday, 29 July 2017 22:38:41 UTC+1, T i m wrote:   > >> Ah, ok, thanks ... that (now) makes more sense as even with that > >> (choke) in and D1-4 out, I've lost the short I was seeing across the > >> mains input. ;-)   you would, 99% of the time     > >Good luck.   > Thanks for your help and I'll let you know how I get on.   > Cheers, T i m   if it's only 1 bad diode try running it without it, on half load or less it should be ok. 2x400v diodes in series should do as replacements temporarily.     NT

T i m <news@spaced.me.uk>: Jul 29 11:17PM +0100 On Sat, 29 Jul 2017 14:45:34 -0700 (PDT), tabbypurr@gmail.com wrote:   <snip>   >if it's only 1 bad diode try running it without it, on half load or less it should be ok.   Now I've got them all out it seems to be two bad diodes but one was reading strange things so maybe died fully as I got it out?   >2x400v diodes in series should do as replacements temporarily.   Ok, I can give that a go tomorrow ... especially as I have so many 1N4004's. ;-)   Cheers, T i m

etpm@whidbey.com: Jul 29 12:10PM -0700 I apologize because have very little info on the lamp but am still seeking guidance. My son has this lamp: Larson Electronics epl-hb-150led. It is a 150 watt high bay type lamp. It has six LED modules and each module is driven by its own driver board. Besides various diodes, capacitors, inductors, and resistors each board has an 8 pin device and a power transistor. There are no other semiconductor devices. Only one of the LED modules works properly. All the others flash for a bit, then stay but don't come up to full brightness, and then shut off after several seconds. Then the sequence repeats. My son figured the LEDs were probably driven with a PWM voltage and so he measured the frequency of the power to the LEDs. The one good LED module is being driven at 150 Hz. The failing modules are being driven at various lower frequencies, depending on which module he tested. My son replaced all the electrolytic caps and this had no effect. The 8 pin device on each board has some sort of opaque coating on it that completely obscures and numbers or letters that may be printed on it. I think the problem with the boards is probably the power transistor. I think the 8 pin device is either a microcontroller or a LED driver IC that is designed to drive a power transistor. The meter my son used to measure the frequency of the pulsed DC powering the LEDs is undoubtably some cheap meter so I don't know how trustworthy it is. From what my son says the lamp is supposed to be some kind of "smart" lamp so that it is more efficient etc. and this is why I think the 8 pin device is a microcontroller or a LED driver. I think the various frequency measurements he is seeing are the result of the power transistors failing. I told him he should order some new ones and try them out, especially since, according to my son, they do have legible numbers on them. Since I'm really busy right now and don't know much about how these things work anyway I'm asking for some advice and opinions. So, is the 8 pin device probably a microcontroller? And are failing power transistors probably the problem? What can my son do to determine what the 8 pin device is? Thanks, Eric

Jeff Liebermann <jeffl@cruzio.com>: Jul 29 01:22PM -0700 >My son has this lamp: Larson Electronics >epl-hb-150led. It is a 150 watt high bay type lamp. It has six LED >modules and each module is driven by its own driver board.   Is the lamp one of these? The numbers are similar, but there are additional suffix letters that you did not provide: <http://www.larsonelectronics.com/p-70368-class-1-division-1-explosion-proof-150-watt-high-bay-led-light-fixture-paint-spray-booth-approved.aspx> <http://www.larsonelectronics.com/p-144814-ceiling-mount-explosion-proof-150w-high-bay-led-light-fixture-17500-lumens-140-beam-spread.aspx>   Only $2,200 each: <https://www.grainger.com/product/LARSON-ELECTRONICS-LLC-Explosion-Proof-Lighting-20LN23>   I don't see six LED modules, although with 12 LED's, I can how 6 modules might work and fit: <https://www.google.com/search?q=Larson+Electronics+epl-hb-150led&tbm=isch> No disassembly photos. Bummer.   Could you double check the model number?   If you only have one out of 6 modules currently functional, my guess(tm) is that you're doing something wrong in the operation of the light. It might be getting too hot, insufficient ventilation, or too much applied AC voltage. Difficult to tell from here. If you repair one or more modules by replacing blown parts with identical parts, I would give it 5 chances out of 6 of blowing up again.   What I do in situations like this is first make a schematic. Identify as many parts as possible. For parts obscured with epoxy, use some type of epoxy softener to ID the part: <https://www.dynaloy.com/products/epoxy> With the one remaining working module, use an oscilloscope to measure waveforms and voltages. Be sure to isolate the light with an AC line isolation transformer to prevent the oscilloscope case from being at AC line potential. Or, use a dual trace scope in differential input mode. After you repair a module, compare voltages and waveforms.     -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

micky <NONONOmisc07@bigfoot.com>: Jul 29 03:37PM -0400 In sci.electronics.repair, on Sun, 23 Jul 2017 13:35:47 -0400, bitrex >> news:s6d7ncdecv29j9dsl1d12it82u8e8gb6ce@4ax.com...   >> Is my 2004 original equipment CD player likely to be able to play Mp3 >> cds (in the car I just bought)?   This is a Chrysler Sebring, 2004. I don't know who actually made the radio.   >> Gareth.   >IIRC my 2002 Ford Taurus OEM CD player would play CD-Rs of mp3 files, >but not CD-RWs.   Well, I made up a CD on the PC and tried to play it and I got ERR.   I guess I could have done this in the first place, but I learned things in this thread, so it was worth it.   I finally noticed that some CDs are labeled "audio CD" and I guess that's all mine can play.       I didn't mention my previous car, a 2000 Toyota Solara with an AM/FM/6-CD-changer in one box, that I still own, which used to work, then gave Err 2, then worked again after I took it out and fiddled with it a little, then gave Err 2 again, repeat previous step, and then did nothing at all when I pressed the CD button.   But I'm selling the car and it has I think 3 CDs in it.   This time fiddling did nothing, and trying to disassemble didn't accomplish much, so I ended up taking out as many screws as possible and ripping the pieces out.   By the time I was done, the laser assembly didn't slide well on its track, so maybe that's why it finally stopped working (though earlier it was the changer that was causing trouble.) Or maybe I damaged the track or laser carriage when ripping it out, though I don't think so.   But I got the CDs out and there were *four* of them.   I don't know who made that radio either.

micky <NONONOmisc07@bigfoot.com>: Jul 29 03:37PM -0400 In sci.electronics.repair, on Mon, 24 Jul 2017 15:06:47 +1200, >playing them reliably). Back then some players started being sold as being >CDR compatible but after a while it became taken for granted and the badging >vanished.   So this accounts for my original question.

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