BASIC 400 Powered Active PA Speaker - Blows Fuses, But Why?
HTML-код
- Опубликовано: 13 сен 2024
- LER #317 I have a BASIC-400 Active Speaker to repair. The Amplifier blows the main fuse, but what is causing the fault? Wanna find out? You just gotta press PLAY!
I work in collaboration with:
The Electronics Channel (with Carlos and Detlef)
/ @theelectronicschannel
Gran Canaria Uncovered
/ @grancanariauncovered (with Detlef and Julie. Not electronics related)
Det Builds Stuff - / @detbuildsstuff (Detlef)
Retro Upgrade - / @retroupgrade (Carlos)
For All Your PCB needs: free $5 discount coupon
www.pcbway.com...
Equipment used in my videos. These are affiliate links, you pay the normal price and I make a small commission.
TEST METERS
ANENG AN8009 MULITIMETER
s.click.aliexp...
amzn.to/4da4Q7h
amzn.to/4fsjkkm
amzn.to/3yuf03q
amzn.to/4fwQOOD
www.banggood.c...
KAIWEETS HT118E MULTIMETER
s.click.aliexp...
amzn.to/3yC0ZRe
amzn.to/3SHIEcy
www.banggood.c...
VC480C+ MILLIOHM METER
s.click.aliexp...
amzn.to/46Gg1Cm
amzn.to/3YwUjyn
MESR-100 ESR METER
amzn.to/3yxQ0Zd
amzn.to/3WSr73A
s.click.aliexp...
XC6013L CAPACITOR METER
s.click.aliexp...
amzn.to/4cf2lzm
amzn.to/4dw9cp5
TM-902C TEMPERATURE METER
s.click.aliexp...
amzn.to/4fAz44L
amzn.to/4fBxD69
LCR-T4 COMPONENT ANALYZER
s.click.aliexp...
www.banggood.c...
amzn.to/3X4rOHv
amzn.to/3Agcj6h
FNB58 USB ANALYZER
s.click.aliexp...
amzn.to/3MgBFnn
amzn.to/4dyLU1H
www.banggood.c...
PCI POST ANALYZER
s.click.aliexp...
amzn.to/4dd8ihw
amzn.to/3LTpeO7
TL460S PLUS PCI_E ANALYZER
s.click.aliexp...
amzn.to/3WEsdi6
TOOLTOP ET120MC2 SCOPE
s.click.aliexp...
amzn.to/4dCaz5L
amzn.to/4dxOYLt
FNIRSI 1014D SCOPE
s.click.aliexp...
amzn.to/3AdZqK1
www.banggood.c...
NPS3010W 30V 10A PSU
s.click.aliexp...
amzn.to/4dzl2yM
T12 STATION WITH M8 9501 HANDLE
s.click.aliexp...
amzn.to/46E73W6
M8 9501 HANDLE
s.click.aliexp...
YIHUA 982 Soldering Station C210/C245
s.click.aliexp...
FNIRSI HS-02 PORTABLE SOLDERING C210/C245
s.click.aliexp...
amzn.to/3Yv7Ma5
QUICK 861DW
s.click.aliexp...
amzn.to/3WDF4B5
amzn.to/4ci7rdW
PROS'KIT SS-331H
s.click.aliexp...
INFIRAY P2 PRO IR CAMERA + MACRO LENS
s.click.aliexp...
www.banggood.c...
amzn.to/4coSRle
amzn.to/4coSV4s
TOOLTOP ET13S THERMAL CAMERA METER
s.click.aliexp...
ET13S MACRO LENS
s.click.aliexp...
OPTICAL MICROSCOPE
s.click.aliexp...
usa.banggood.c...
amzn.to/4dzBA9G
TOMLOV TM4K AF FLEX
amzn.to/3LY0YKs
tomlov.com/pro...
TL866 II+ PROGRAMMER
s.click.aliexp...
amzn.to/3SGKL05
CH341 PROGRAMMER
s.click.aliexp...
NC-559-ASM FLUX
s.click.aliexp...
DESOLDER BRAID (I use size 8045)
s.click.aliexp...
s.click.aliexp...
HX-T100 SOLDER (0.6MM)
s.click.aliexp...
ESD-11 TWEEZERS
s.click.aliexp...
If you would like to support this channel
You can send donations
www.paypal.com...
You can subscribe to Patreon
/ learnelectronicsrepair
You can click Join to become a channel member
Thank you
Richard
It might be worthwhile to check the bad secondary to ground and if grounded remove the toroid and check for rubbed through insulation around the mounting plate. Regards, David
That makes some sense - I'll have a look
That's smart indeed.
I'm sure I'm not telling you anything new, but when I have stubborn components that don't want to release from the pcb- i flip the pcb upside down and just feed a massive glob of fresh solder that covers over all the pads at once and it just falls out. Its also how I remove multi pin amplifier chips too. Thanks for sharing all your knowledge with us!
Nothing new, I do that quite a lot on video but you are right, it's a very good technique 🙂 There are always many ways to achieve the same result in soldering.
Thank you for all your videos sir I have learned a lot from viewing them .
To narrow down where the current was going to, don't forget you can read the voltage across fuses. Any fuse feeding a near short will show a meaningful drop across it. This can also help find when someone installed too large of a fuse in an attempt to keep the current flowing. In this case they got their wish haha
I was surprised that you didn't zero in on the supply section quicker as the DC fuses were not blown - but then armchair technicians are like armchair quarterbacks! I had my money one the voltage selector switch - cheap switches plus island environment, a little corrosion, a little heat, some melted plastic - pop goes the fuse. Thank you for sharing the process - always interesting no matter the outcome. Regards, David
I was shouting transformer, you know that bad feeling...Edit reading another post seems there were MOVs or caps there too, so not just bridge and reservoirs..I was skipping through and someone said he measured a short?
@@martinda7446 If there were any MOVS there then A: they were the special transparent ones and B: They changed the resistance of the secondary winding (with the transformer disconnected from the PCB)
@@martinda7446 Yes, a bad feeling indeed but that toroid looked sooooo good on the outside.
@@davidv1289 Yes it does, if it looked distressed I would have homed in on it much quicker
David, absolutely it’s easy for someone watching and then to say at the end why didn’t you look at the transformer first. I like a lot of others enjoy watching and learning from someone actually doing.
Low melt solder works great when the board is really thick or the component itself has legs or heatsinks incorporated... that way there is less chance of damaging the PCB, plastics or components near it.
Long drawn out, loved it, and learned a lot, regards. 😁
Thank you, that is the whole idea of the channel
Personally, I would have pulled the high voltage fuses before pulling the MOSFETS. I'd need some measurements to be sure, but I think it would have accomplished much the same as far as isolating the fault.
I was thinking the exact same thing and was about to type that until I saw your comment
In retrospect I totally agree with you 😉
Russell I’m not quite sure what you mean? There is only 1 fuse in the 240 and surely leaving that out is only isolating the iec input which is basically like leaving it unplugged and then what. Unless I’m missing something?
@@deangriffiths8107 We are talking about the 2 load fuses on the PCB itself.
Thanks for the reply Eric that makes sense now, I had a couple of shandy’s last night when I commented so this went over my head.
Thank you again.
I am but a mere electrician, but when looking for faults i always work by "big fault, big components first". Since the transformer was easy to unplug, it would have been the first thing on my list to cross off. BUT i seldomly have two of a kind, so comparing resistances of the winding helps a lot.
However i enjoyed the methodical hunt alot. Always learning new stuff... like where the hell do i get a lightbulb in 2022? 😀
I was planning on building uC controlled current monitor that cuts power to a device when a selected current is exceeded. Dunno how useful it would be though.
I have a digital current control power supply I used for DC stuff that's super handy. I bought a cheap voltage/current control module off of Amazon for $10 and put it on a large DC supply. It's a boost/buck converter. Gives milivolt accurate and miliamp accurate controlled output, and has auto current limit or shutoff. Goes up to 30 or 40 VDC from .001 to 20 amps or so.
For AC you'd need something smarter and more expensive but almost everything ends up converted to DC in circuit anyway so I have yet to need one.
The reason why I didn't find this fault earlier was not because I wanted to make a good investigation video but because shorted turns on the mains transformer is really uncommon, and especially so without it looking physically burnt/distressed.
@@LearnElectronicsRepair I see, this is perhaps because my contact with stuff is a bit different. I usually had to deal with either stuff that was hidden inside wall boxes with insufficient cooling, smashed components (if they don't fit, they'll find a way to make 'em fit) or with stuff in heavy industry settings where there was so much metallic dust going around that you could meassure the air with an ohms meter ;-D
@@DasIllu I think this is a likely case of too much knowledge slowing me down. I agree someone with less experience of these amplifiers would likely have found this fault quicker. But hopefully more viewers will know about it now if they ever come across it.
Regards light bulbs, I buy then from the local shops, is there a shortage of them? You can also get them (halogen ones which work just the same - in fact some of mine are halogen) from AliExpress, Amazon, Ebay etc no problem so I don't think I'll be panic buying in the near future 🙂
Can you explain you current limiting light bulb in a video? How it's wired/works?
Wonder if that would have shown up by checking AC voltage output of the transformer ?
If the transformer overheated I would expect the thermal fuse to go , so it’s strange to get a shorted winding with no obvious cause.well done !I would have struggled with this I’m sure
I need help to fix mine
The thermal fuse is usually touching windings on outer part of transformer and can sometimes be replaced. A dodgy job is to short the fuse but then you have no thermal protection!
How do I get a hold of you to show you a picture
Try searching RUclips for transformer thermal fuse , there are a number of good videos
PS it’s important that you find out why the fuse has blown !
would measuring the inductance of the transformer coils have helped?
I think one solution to removing the fets would be to use low melt solder or to acquire a large soldering iron wide enough to cover all three connections at the same time, such as a hobbyist wood burning type hi wattage iron
Yeah that could well work - there are always a number of different ways of doing this sort of job.
Measure that transformer using an insulation tester (or similar like Megger). Plus measure the primary against the secondary. The insulation tester will tell you quick if you got a shorted or open winding(s).
The transformer causes a short condition when it isn't even connected to the PCB. And the secondary winding reads low compared to a known good one. What more is there left to prove?
@@LearnElectronicsRepair Wanted to see if the short is just between the pri winding or went through the pri -sec, or shorted to the case. Doesn't matter... However using the dim bulb tester, plug in that transformer with the secondaries disconnected... see if your dim bulb light is bright or not. Should be a easy and clear verification if the primary is indeed shorted to itself.
Always start where the power goes in and follow it through (its far quicker)
Hi Mr C. Thanks for ur education. I would like more info on how to build a good isolation transformer. I had no priar education in electronic most of my info was studying thru utube and books. I would like to learn more and about oscoloscope I bought my own one caltec cs9020 analog. Please sir need more education. Thanks
A short in the Transformer, not something to think about at first. Good find - thanks for showing and uploading this video
Yeah, not the first thing that comes to mind indeed. Likely overheated somehow.
It absolutely is. And it was glaring at him. He said it pretty much...Then went on to fiddle upstream. We have those bad days.
@@martinda7446 Not a bad day really - in the end it was fixed. We can't always do things in the shortest time and I don't really think that matters either. Getting there is the most important - the journey is usually interesting 😉
Reminded me to ask a question been bugging me for months. When you mentioned using your thermal camera, it reminded me to ask if capacitors that are not working get hotter or show cooler than ones which are good? And a supplementary.
I'm always impressed by the precision of the characteristics component makers list and I wondered whether a predictable working temperature can be stated for most components? It would be a function of their wattage, composition and size? It might be quite a quick way to diagnose faults if components had a stated working heat output? Or am I being lazy and looking for a quick way of doing something that can only be done the hard way, with skill and experience?
Yeah I've been wanting to add a thermal imaging attachment for my phone for this reason. I've even considered getting the Cat branded smartphone (it comes with a Flir camera built into it from the factory) even if I just used it as an offline unit (the appeal being the rugged design and impact resistance it has.
Anyway, with something like that recording when you turn on the mains, even if brief, there should be a hotspot right?
Seems like a potential time saver for sure. I haven't been doing much of any PCB work lately so I've shelved this "need". Chasing smoke and using an infrared thermometer to guestimate the source will suffice for now.
TL;DR I agree a thermal camera would make quick work of identifying the heat source.
Hello, please make a video for the current limiting light bulb :))
Have you ever fixed a Beringer I nuk 3000 Amplifier I have an issue with mine it goes into protection won’t come on
I always learned to rule out stuff instead of random chasing faults. I would have started at the transformer, disconnect the outputs and see what happens. In this case the video was done in about 5 minutes.
It wouldn't have been a very good video though 😆
Brilliant, I love it when the Milliohm meter comes out.
I suspected a faulty transformer earlier on, but didn't know if transformers fail often.,
I would have checked the fuse in the working amp to confirm rating. Anything not sealed with a blown fuse, might have had it swapped by a DIY bloke with something random he had at hand
The fuse rating on the cover says slow blow 2.5A 😉
Good thing you had 2 to compare.
Omg, Use your phone and take the picture Rich and that expanded it to see numbers like me 😆 🤣
Same as I do...they are shrinking numbers on everything
@@shagreobe I normally just use the bench magnifier or overhead camera, but yeah your method works just as well
Very hard to find a shorted turn in a transformer unless it a short between each end of the coil. A shorted turn in the middle of the windings will not show up with a resistance test as one turn will not change the resisance much. Bit as you say a shorted turn will show up with AC as it will be a one turn secondary looking into a short circuit and draw lots of current.
Lets hope that they used an off the shelf transformer and not a custom job. The other thing that can cause the fuse to blow is if they have removed the transformer and not put it back on corectly. the mounting bolt through the middle can be seen as a shorted turn if it gets connected together at each end on the outside of the transformer.
simple test with a neon lamp and 9v battery can spot 99% of shorted trannies
Your comment on the mounting bolt acting as a short is very interesting. It would not of course produce the resistance readings I got on the bad transformer secondary, but I will definitely keep that in mind for the future 🙂
@@LearnElectronicsRepair DC tests will not show a single shorted turn E,g resistance measurements, they will show if the ends of the windings are shorted. Or a major breakdown of the windings due to overheating, but I expect you would have seen signs of internal overheating on the outside. If the transformer is scrap then unwinding it might be the way to see what has occurred to it.
@@karltest1314 Which is why i said you can't find a shorted turn with a DC resistance meter. you need an AC componnent.
Don't mix the current fault and the previous fault, the last is just the outcome of the first. A slowly overheating winding will not blow the fuse as it build up to breaking down the insulation. Once the insulation breaks the last fault appears in which now it will blow fuses in an instant. First fault was the cause the last the affect.
@@TheEmbeddedHobbyist I hear what you are saying but IMHO you can (sometimes) find this fault using a DC resistance meter when you have a known good one to compare with. I'm confident I proved that with the Fluke, then went on to confirm it with the Milliohm meter 😉
Hi Dicky, will there be a follow up video on the repair of this unit, your videos are always great 🤙🏼🇦🇺
I have to say this one is pretty much conclusively proven and finished - unless he has a replacement transformer from a scrap speaker or something like that.
@@LearnElectronicsRepair why not try and see the fault in the transformer and then try to rewind it? Oh btw, you probably know this trick, but use a cr2032 battery to test LED’s on camera if you want people to see it light up.. also use the dmm on continuity to test fuses.. just a couple of suggestions that’s all.. 🤙🏼🇦🇺
16:41 - I'm thinking primary xformer winding?
51:25 - Ah... Secondary windings. Thermal damage??
My home speakers keep blowing fues how do I find the fix
I need help to fix mine
Thanks, learned a lot again!
I seem to remember that your "current limit" lightbulb still went on with the transformer out of the circuit - wouldn't this cut across a transformer error?
Nice question...
Heya, tranformers do brake down to bad but that's what happen
Hi sir,verry nice, thanx videos repair amplifier
Typical crappy Chinese construction and cheap parts. You have my sympathies. Thanks for the great video!
The only time ive had something blowing fuses with no short , was a tv i was working on, a small blue ceramic disc capacitor on the primary of the psu had a hairline crack in it , and after i found and swapped that it stopped blowing the fuse
So it expanded from heat? Or created an arc?
@@TheDurdane im not sure why the cap failed , it was connected to one of the pins on a mosfet on the primary
What is that 'stuff" covering the inductor, that seems to have been spread across to R147, then a string across to C92 and D35?
Thermal paste?
Size of that toroidal, 2.5 seems low. I was guessing 3.15 minimum.
I've just looked at the specification for the active speaker this is from, and it says the output power is 450 W + 100W.
It's amazing how they get all that power using a 270VA toroidal transformer. It's magic, I tell you. 🔮🪄 ⚡🔊
Or they redefined Watts like the hard drive manufacturers redefined megabytes? No one seems to have an issue with that particular method of short changing us 😉
Bummer on the bad transformer. Guess it's a parts unit now. Fortunately fitting a basic AMP to the speaker is cheap and easy. Here in the US people mostly just chuck it in the bin and buy another. What a waste :) more junk for me to salvage!
Iv got abit of an issue with something im working on and wondered if any of you clever cloggs could point me in the right direction . So ive got a panasonic dvd/vcr recorder, which needs a firmware update, the update isnt available anywhere , i have the main board from the same machine which has a different fault but should have uncorrupted firmware, my question is where would this firmware be stored , i know on tvs its usually an 8 pin bios ic , am i looking for something similar here? I want to swap the chip with the firmware over to get one working machine out of the two bad main boards . Thanks for any help
I suppose what im really asking to clarify, is firmware always stored on 8 pin bios ics in most devices ? Im not a software guy whatsoever hence me being so clueless
Update: firmware was on a 50 pin chip, machine now working
Like your videos and appreciate you sharing your knowledge. Would you consider a different camera angle. Your head seems to block the view when your probing the circuit.
A good test would be to change the good amplifier transformer into the one that is not working ..that would prove the problem is the transformer. (note: I also think it is)
I fail to see how that would prove anything at all - seeing as the fault condition is present when the transformer is disconnected from the PCB. However your comment has two likes, so am I missing something important here? If for example the transformer worked when connected to the other PCB what would be the conclusion?
@@LearnElectronicsRepair Connecting a working transformer to the "faulty" system would eliminate the possibility of another component on the faulty system be the cause of other malfunctions.
@@John_Smith__ That's a fair comment - I agree with you it would prove the PCB is good or not
@@LearnElectronicsRepair I've just said that because usually "power" transformers do not go down without "collateral damage". So just from a precautionary standpoint they may have caused some further problems on the board, even if the obvious problem is indeed the Transformer.
Re LEDS you didn't notice the round and square pads.
I noticed the K markings on the PCB. I think the part about the internal structure of the red and green LEDs was quite interesting and maybe useful to some viewers.
Also, LED housings have a flat side that marks the cathode.
Probably thats the output ..but not quite sure😂..
i love your videos.
Cracker jack school of amp repair... Lol
IF IT WAS ME I WOULD UPGRADE THE MOSFETS,! higher amps and higher voltage,, plus new transformer
To achieve what? (replied before you edited your comment to mention the transformer)
@@LearnElectronicsRepair Higher tolerance margin in the FETs? Although the fuses should stop damage to those.
@@_Stin_ exactly. people make mistake of just replacing like for like, but while ur in the unit upgrade just as cheap,, i been a engineer for over 30+ yrs in ind and fix amps on a regular basis, but thats just what i would do, mosfets that are too weak put a very large strain on caps and transformer, if they dont switch fast enought they cause, ware on transformer, higher amps mosfets and power output quicker push n pull. releaving transformer having to work harder, less strain,,"also transformer doesnt have to be exact same voltage out think them transistors can handle much higher voltages, on output stage, you would need to check, on what they can handle if ur keeping original fets, but like i say i would upgrade them,
400 speaker with 270VA transformer....
You have to remember that music power is different from electrical power. its just put on the labels to sell more amps. 🙂
Yeah... That is just a model number 'coincidentally' chosen and having as main purpose to rip of customers. It is written nowhere these are Watts. And if it was written 'W' or something along it that would never mean Watts as we know it to indicate the rate of energy transfer.
@@karltest1314 And rms is just used to compare the power of AC to that of an equivalent DC power, with music the Crest factor needs to be considered as well.
@@karltest1314 Agreed - It's RMS of GTFO lol
@@Joe-by8jh where did you see me defending it, and yes i used to design audio units! But at £25K plus a unit it's not what you would call cheap junk.
I also was just pointing out that AC voltage defined as RMS is just a way of stating that a voltage of 240Vrms or 240V dc will provide the same power in to a resistive load. if you think of voltages that are not a sine wave you need to also include the crest factor to get the correct rms voltage. and thus the equ power.
So at 400W's that's just about 1/2 a horse power. or maybe we should bring Mr Bel and his friend deci to the dance party.
U are rattling the wrong bush .its not the transformer .there are 4 blue caps on the pc board .one or more are blown .did u forget u tested the board without the transformer and the short was still there
I also think it have seen high voltage and one off the MOV have shorted
Aha I was shouting transformer ar rhe beginning...But then I didn't see any MOVS or caps..
Hold on one minute!!! So the transformer
A: causes the current limiter bulb to come on full brightness when it is NOT connected to the PCB
B: the DC resistance of the secondary reads low (compared to the good one) using multimeter and Milliohm meter
Before you convince me to try your suggestion please explain how the short condition caused by the 4 blue caps on the PC board is still causing a short when the transformer secondary is not even connected to the damn board!!!!!!!!!!!!!!!!!!
@@flipjonker116 Where is this MOV? Tell me and I will check it
@@LearnElectronicsRepair Agreed. My initial inkling was transformer/power input. Very thorough check, there. Caps can't cause a short if they're out of circuit. Thermal stress degrading the insulation??
Move your head...