[0:00] there we go so so that lights up nicely
[0:04] so so we’ve had a slightly annoying epidemic of light bulb failures in the house so these

[0:12] two are definitely completely dead um this one’s exhibiting some quite interesting behaviors so

[0:19] let’s plug this in sorry about the noise and turn that on you can see I think you

[0:26] can see that it’s slightly working and a bit flickery and very very faint so not working

[0:34] particularly well um this one is the only bulb that actually works um properly so let’s plug this
[0:42] in that’s uh pretty bright so these are supposed to be I think they’re either 100 Watts equivalent

[0:52] or 150 um I’ll look that up and put it on the screen but I’ll leave this plugged in for a

[0:58] while because one thing I noticed is the the base of the bulb seems to get quite hot so I’m going

[1:03] to leave this plugged in and then we going have a look at it through our IR camera and then we’ll

[1:08] take some of these dead ones apart and um try and diagnose what’s actually happened so I’ll be back

[1:14] once this bulb’s nicely warmed up so uh while that light bulb’s nicely warming up I thought I’d take

[1:20] apart one of the broken ones um it was a bit of a mission and unpeel the uh outer can and snap

[1:28] off lots of plastic and and then um get of lots of this um weird Brown I guess kind of glue type

[1:35] stuff so but we’ve done it so this is the wire that goes to the bottom of the light bulb so that

[1:43] kind of sticks through the base and connects to the end cap and then this white wire um goes out

[1:52] to the outer can so it connects sort of somewhere probably around here um slightly annoyingly

[2:00] the actual B seems to be sealed so getting these um getting these led strips out will probably

[2:07] involve smashing the glass so I’ll do that and get those out um looking at the circuitry it’s

[2:13] more complicated than I expected so that’s kind of interesting um I suspect what’s failed is either

[2:22] this capacitor or one of these two capacitors so what I’ll do is I’ll take a photo of this and we

[2:28] can have a look at the um actual ICS that are being used I guess that’s some kind of bridge

[2:32] rectifier and this will be some kind of um possibly a switching power supply I see so

[2:39] that’s kind of interesting so I bit the bullet and um smashed the bul so I could extract the um the

[2:46] actual filaments uh only a small injury not too bad so it’s quite interesting um I’ve taken one of

[2:53] these out I was trying to power it unfortunately these need a higher voltage than my bench Supply

[2:58] can provide uh I could resurrect my high voltage driver circuit maybe I’ll do that um another time

[3:04] but anyway it’s um it’s a fairly straightforward construction so we actually have four LED

[3:12] filaments coming in and four coming out so the probably the positive attaches to one end and the

[3:18] negative to the other and then you have um four in parallel and four in parallel and then they’re

[3:24] both in series um so quite interesting yeah maybe I will try and drive this later it could be

[3:30] could be a fun project but let’s have a look at the PCB talking of pcbs we should probably mention

[3:35] PCB way so I curently have um my es32 Spectrum being manufactured with them so it’s currently at

[3:42] the silk screen stage so getting pretty exciting move on to SM assembly next so I’m looking forward

[3:48] to actually getting those boards it is the first time I’ve ordered so many boards so it’s a pretty

[3:54] nerve-wracking so this has been baking away for a while let’s have a look with the firal camera

[4:00] at what we’ve got so on the end that’s about yeah 50° 47° not as hot as I was expecting it

[4:08] feels very warm but it’s obviously not actually that hot so let me try and arrange this so you

[4:14] can see so yeah so about 45 46 on the end there um and then the actual bayonet it’s

[4:23] not that hot 29 um inside yeah around 46° um definitely is warm towards the bottom but it

[4:32] it’s not it’s not spanking the hot is it that’s uh it’s actually not that unreasonable um so
[4:39] interesting yeah well let’s look at the um PCB and then we’ll have a look at the capacitors

[4:48] and um see if they uh see if they’re broken or not but this was running for around kind

[4:52] of 40 minutes um 45 minutes um it’s warm to the touch but not boiling hot um interesting so our

[5:02] failure mode is still a bit of a mystery we can actually see almost see inside the bul to the uh

[5:08] to the filaments so the PCB is actually pretty simple we have the bridge rectifier here and

[5:14] then we have this WS 9561 IC so this is a 72 volt um LED driver and I think we’ve got a fairly kind

[5:23] of um offthe shelf um circuit layout for this so nothing particularly exciting here uh and no clues

[5:30] as to what’s wrong okay so we got the PCB here I have managed to desolder all the components

[5:36] and but let’s just check some things on the PCB so we have our fridge rectifier here so let’s

[5:42] check that I’ve got on my multimeter on diode mode so let’s see we should this the right way
[5:51] around yeah so 6 going that way and we should have 6 going this way oh yeah

[6:02] so Bridge rectifier is fine there’s a little shocky diode here let’s see what that says so

[6:10] see point five volts that seems fine as well um a bunch of resistors but I can’t think anything

[6:17] wrong with those so here’s all our components let’s check them to see if they’re right so

[6:21] we got my nice LCR meter here so let’s check these um let’s check these capacitors first

[6:29] so let’s do the inductor first since it’s already on inductance so looking at this inductor um here

[6:37] we go looks like one Milli Henry don’t if you can see that yeah one mli Henry so let’s check this
[6:46] then well looks a bang on one mli Henry so definitely not the inductor

[7:00] and let’s try this capacitor so this is a 3.3 come on focus camera 3.3 microfarad

[7:11] so let’s go on to the microfarad range and let’s see what this is
[7:17] doing three microfarads so that seems pretty reasonable as well okay

[7:30] and then we have this one which is supposed to be a 4.7 micro so let’s try that
[7:39] out four micr fads so seems reasonable as well and then finally we have this this

[7:53] little capacitor here um difficult to read because it’s covered in junk um but let’s uh

[8:00] let’s just measure it and see what it
[8:02] is so looks like that’s a 100 nanof so interesting um as far as I can tell all the components seem

[8:19] okay and the bridge rectifier is fine and this diode’s fine um I guess this chip maybe that’s

[8:26] gone faulty um it’s entirely possible I was thinking about the temperatures we measured

[8:32] it was 50° on the actual end cap um so this PCB is getting pretty hot because it’s inside

[8:39] the bayonet so I don’t know what the temperature was inside but pretty toasty um so yeah a mystery

[8:46] but these bulbs all do seem to be failing so goodness knows what’s happening so I’ve made

[8:51] myself a very Heath Robinson um power supply here it’s currently um 126 volts I mean it’s incred

[8:59] be low can’t but I do need to be a little bit careful that I don’t um EXA myself so we can

[9:03] take let’s take this filament that I chopped out earlier and see if we can get it to light up so

[9:10] let’s see I don’t know which don’t which end is positive and which one is negative so let’s try

[9:14] and there we go so so that lights up nicely so that filament’s definitely working let’s

[9:23] try um let’s try all these ones so let’s connect let’s try connecting this end to

[9:29] positive and then this end negative yeah so there those three work as well um what about

[9:37] uh about these four I don’t know which way around to actually wire this up so let’s try

[9:43] positive there negative there well nothing that’s interesting um let’s try spping that
[9:50] around positive there negative down the bottom still nothing so that’s

[9:59] kind of interesting what I’m going to do is I’m going to chop all of these

[10:02] out individually and we’ll test them all separately so let’s do that quickly
[10:08] um now it might just be that because there were four my um little crappy power supply

[10:16] couldn’t actually drive it but let’s have a look so got my four here so sure must be a

[10:23] slightly easier way of doing this um but let’s try them one at a time so plus minus other way
[10:35] around M oh well that’s interesting this one appears to be completely

[10:43] dead fascinating let’s put that to one side let’s try these other ones

[10:47] maybe maybe I’m doing something wrong here oops negative positive
[10:54] nope positive negative nothing let’s double check was working so let’s double check I’ve

[11:06] not broken something oh yeah that’s that lights up interesting and these three will light up

[11:13] without any problems these ones appear to be not lighting up at all so let’s see positive

[11:20] negative nothing and negative positive completely dead well that is interesting um so that appears

[11:35] to be dead let’s check this one negative and positive absolutely nothing flip it
[11:42] around negative yeah this one this one’s not lighting up either so well I I guess

[11:54] this must be the cause of our problem these all of these strips have died
[12:02] so what probably happened most surise is possibly one of these went open circuit

[12:11] and then all the current started fling through the other ones and then they

[12:16] slowly died as well because there was too much current flowing through so and then

[12:22] when they all died nothing worked anymore the light bulb stopped completely so well I think

[12:29] my conclusion is that um these four strips are dead now these four strips working
[12:37] nicely let’s make sure the right way around sure I’m not going mad yeah that that lights

[12:45] up no problem so yeah interesting so the the circuit’s probably fine the

[12:51] PCB is probably fine it’s actually these led strips that have been failing so yeah that’s
[13:00] that is completely dead it’s not lighting up at all interesting

[13:06] well I guess we’ve diagnosed our problem um yeah very cool