Been binge watching you channel this last week, love it :) Reminds me when i first started out doing repairs at a music shop around 86/87 time. Someone had this old Fender transistor PA mixer / amplifier that the output stage would kept failing after some use. The guy doing the audio repairs at the time just kept shot gunning all the failed silicon in hope it would cure the problem, which it didn't. Eventually i ended up looking at it with the main service guy and we found the culprit to be a diode in the output stage bias circuit going open circuit when it got hot and the bias current went though the roof taking out the output devices. Once we swapped that out, no more failures. Testing it cold though there was not perceived problem with it. Sometimes you have to think out the box a bit when fault finding :)
This is also quite a common fault with leaded diodes and I am sure its caused by bending the leads and stressing the diodes internal end connections , for this reason if I am bending the wires on a diode I always hold the diode with a pair if snipe nose pliers and then bend the wire while holding the diode in the pliers so there is no movement at all occurs near where the wire goes into the diode body .
Nice one! Thanks for sharing Michael. I can remember a similar thing happening when I was a workshop engineer in the early 80's and field engineers used change the so called stock fault 910 ohm resistor in the Bush T22/T22A chassis and the heat from the soldering iron used to temporary make the actual faulty component (a BD2xx tab type regulator transistor, same package as a TIP41) start working again for a few weeks, until it eventually failed again. The 910 ohm fed the transistor base, and only a few mm's of track between them. All those set went wrong again, and came back to the workshop. The transistor always measured faulty in circuit but removing them they measured ok after being heated from desoldering. Replacing the transistor with a new one, a long soak test and returning to customer, they never failed again.
Yes I remember the 910 ohm resistor, it fed the base of the series pass regulator transistor and got so hot it changed color, glad you liked the video and it brought back memories of better days .
@@michaeldranfield7140 , Yes loved the video, a very useful tip. I still repair the odd TV that work mates bring in from time to time. I work in electronic and electrical machine training and education now to hnd / foundation degree level. However, I cannot resist getting my hands dirty on TV now and again 🤣
Bush T22 I remember those !!! Crazy era of switch mode power supplies running all the time in standby mode. Waste of power and just asking for short lifed components !!
Always a pleasure to see you work, and (I would bet) that you worked on the old valve CRT TV's too. Thanks for your videos, because it saves the hassle of scrapping them, and I have had an extra 10 years of use from repairing a Flat Screen. The only downside to their age, is that many are power-hungry, by comparison to those which are manufactured today.
@@michaeldranfield7140 Yes, me too. a lot of B&W sets failed due to Valves failure. I think that I used to place a 68 ohm resistor in the octal base (Heater). If all the Valves lit-up, you had pinpointed the faulty Valve. But I didn't progress to learn as much as you! I am happy to watch all of your YT vids. You are most definitely saving hundreds of Tv's from going to their final resting places. Thanks for your reply. Greetings from Sydney.
sorry no , with most flat screen TV sets there is no service manual so fault finding after you have tried the basics is sometimes more good luck than knowing what your doing sadly .
Thank you Micheal i am looking to use this tip today. On an inverter board i have one sm diode witg 24 volts on one side and 5volts on the other side. It tests okay in cct.Should i change it? Thanks Michael
Great tip! They must use super-garbage parts.... I've always specified Vishay, Diodes Inc. etc. in products I've designed and never had a problem.... 20 years on still doing their job..
Dear Sir, I do have some questions: 1. What do you think could be the reason for Vertical Banding, Grey Uniformity Issues, and Dirty Screen Effect (DSE) in modern TV's Panels? 2. From Longevity point of view, are Direct-Lit Full Array LED TV's better (Like Bravia 3, in which constant Backlight is ON) or the Mini-LED Local-Dimming ones (like Bravia 7, 9 in which hundreds or thousandsof LED's turn ON and OF and show varying degrees of Brightness to produce best Contracts, darkest Blacks and Brightest Whites, etc..).? Which among them will be the TV with longer life ?? 3. I'm assuming keeping Brightness low shall increase the life of the TV. Waiting for your reply. Possibly if you could make a video, it'd be great! Thanks.
Is there any particular brand that you have found to have better quality capacitors and components? I know that more money =\=better quality. Is there a brand that you know uses better caps and components? (I figure you've opened quite a few televisions and been able to see what kinds of components they use)
Comment about LCD TVs possibly having a fault like this is something for me to explore with my 4 blink Sony problem. Michaei I have a request re your Sharp LCD recent 2 blinks repair.Thank you
All we used to do is replace the PSU in the field , when the call was booked the operator would follow a flow chart then send the panel suggested to my by box for collection the next day. sometimes they worked.
when replacing with wire ended types be careful to bend the leads while holding the diode lead out with a pair of pliers,otherwise you can end up with the same problem further down the line, an intermittent junction contact .
Hey matey - thanks so much for the video (and the others that i have watched) Just wondering - where did you learn all of this, I have 30ish faulty DC to AC inverters I would like to diagnose and fix. Some are overheating and causing screens to black out... My knowledge is basic, but is growing by watching your videos! Thanks again - James of NZ
The forward voltage drop can rise in a diode if the ESR of the device has risen. Test it at a higher current. Also...if there are high frequency spikes, it's internal junction capacitance can make the device leaky. As a footnote it is warming to see a REAL electronics engineer like me who has watched as his watched while the subject of his career passion turned into disposable junk. This is why I now work with industrial & scientific gear...
First time I came across high forward resistance diodes was back in the 1980s and these usually test OK when they have been heated by desoldering, its for this reason I think it's caused by a bad contact between the junction and the lead out and this is why now when I'm bending the leads on wire ended diodes I always hold the lead with a pair of pliers as there is no mechanical stress placed at the end of the diode.
@@michaeldranfield7140 Funny thing that...I came to a similar conclusion back in the "good old days" as well & do the same. We come from the same era when technicians were real technicians, a day when Philips service manuals were half an inch thick & cost a fiver from CPC & when the City & Guilds was a good qualification.
Interesting video. there are always 'common' type faults in every type of equipment. From tv's with no service manuals to the biggest computerised medical equipment where the service manuals stack to a height of 600mm :). I know I have worked on them all. One small observation, the diodes are a 14007 not I4007. The 1 indicated one junction device.
I have something going on like that, I'll check it out. But its reverse, TV starts up fine "cold", but then later doesn't. Sometimes switching the mains leads around makes it work again
Have you ever seen an LED LCD TV where the screen goes black after a few minutes but still has sound and backlight? Stays black when powered on for at least a month, but if left off for a few months, starts up okay then, again, goes black after a few minutes.
cant say as I have seen that before and it sounds like its going to take a bit of finding its its intermittent , a hairdryer may be a good start , see if you can bring the fault on quicker .
@@michaeldranfield7140 The fault starts reliably. The problem is finding out what is normal to compare to. It also seems strange that the issue persists for weeks even when unplugged and cold, as though a charged capacitor maintains the fault until it discharges.
@@atholmullen you could try a gentle tap around of even touching different wires and connectors with an insulated took , intermittent faults can be very time consuming to find .
Thanks for the tips! Are you using a Pace rework station? Looks a lot like what I worked with back before I retired from communications. Now I only have an ols first gen Pace desoldering station. BTW wher did you obtain the semiconductor tester? I see you also have several other testers made by the same company.
I use a Pace soldering station, this was £1600 when I bought it 20 years ago and in times gone by when I was super busy it was running 8 hours a day. I have a lot of peak testers as I know the guy who makes them, he is only 5 mins down the road on the same industrial estate as me.
@@michaeldranfield7140 How about I put this one into a playlist on my channel ? Something like 'Fault finding hints on modern electronics' ? If I stumble about more of these things I can collect more of this to help spreading this information.
Cheers Mike nice one man really good video 🤟👍 I’ve not had that yet on these, well I probably have but just board swapped it because I couldn’t find. I’ve had good luck replacing the flash roms on these when there’s no Pson signal, but the ir and buttons have triggering signals to turn the set on. Fixed a cheap nasty JVC hifi thing today with the class D fitted on to the same PCB as the SMP which I’ve never seen yet! Absolute junk this thing was, a shorted SR100 diode on the secondary was the issue 😎
@@MrReeceyburger123 I have quite a few Peak testers, more than in the video , I know Jeremy who makes them, he is only 5 mins away from me at the other end of the industrial estate , I even have his very first transistor tester that I think he designed as a uni project , well before he set up in business .
Since 2008, I've had THREE flat screen TV's. A Panasonic 1080P Plasma. A Samsung 1080P LED LCD. And currently a MORESENSE 4K ULED LED LCD. All working perfectly. No faults at all in 14 years! ...... I also have a 40 year old SONY TRINICON Colour Video Camera, and matching 38 year old SONY BETAMAX VCR! You've guessed it, at a combined age of 78 years, both still working perfectly! ...... I also have a 43 year old JVC STEREO AMPLIFIER ... but this is getting boring? 😂😂😂
Great informative clips. Congradutions. My question is if the diodes you removed still test ok can you reuse them for the same application? It feels like an installation problem more than a part problem?
His diode tester probably doesn't put much current through the diode... More current would probably have shown it still being at fault. Or like he said, heating it up temporarily "fixed" it and it would probably fail again later. They are cheap, so you may as well chuck em...
@@michaeldranfield7140 Yeah - false economy - ...and no self respecting technician would want to court reworking (and good reputation), when the same 2c component fails again.
next time - let's film the entire footage of removing and then replacing the resisters and then play the results .... the way is is filmed -- you did replaced the parts but the next scene shows the tv working -- not knowing if it was the actual bad parts as the culprit ... it just makes sense this way ... great video but needs to show facts thereafter ....
I get where your coming from but I think most people watching youtube are just looking for a quick fix and not wanting to watch an hour plus long video .
I think the real problem here is not the diodes at all. The real problem is a cold solder joint. All you would have to have done is reheat the joint with some flux and that should have fixed the problem. Diodes don't fail like that and then fix themselves.
I've seen this happen to the older through-hole 1N400X series diode, but only from many years of 24/7 use, and mild overheating. But I don't see any evidence of that on your TV board. I guess this is just a bad batch of them? Shouldn't happen.
I first came across this problem in the 1980s on a TV that had a whole load of leaded diodes like 1n4007 that were painted silver so it may have been a bad batch then But I'm pretty sure on leaded diodes it's caused by a poor junction to lead out most likely caused by stressing the junction bending the wire and for that reason I only bend diode wires while holding in a pair of pliers. But as you say heating and cooling plays a big part in the failure mechanism.
Great tip Michael, thank you.
Thankyou for that .
Been binge watching you channel this last week, love it :)
Reminds me when i first started out doing repairs at a music shop around 86/87 time.
Someone had this old Fender transistor PA mixer / amplifier that the output stage would kept failing after some use.
The guy doing the audio repairs at the time just kept shot gunning all the failed silicon in hope it would cure the problem, which it didn't.
Eventually i ended up looking at it with the main service guy and we found the culprit to be a diode in the output stage bias circuit going open circuit when it got hot and the bias current went though the roof taking out the output devices.
Once we swapped that out, no more failures. Testing it cold though there was not perceived problem with it.
Sometimes you have to think out the box a bit when fault finding :)
This is also quite a common fault with leaded diodes and I am sure its caused by bending the leads and stressing the diodes internal end connections , for this reason if I am bending the wires on a diode I always hold the diode with a pair if snipe nose pliers and then bend the wire while holding the diode in the pliers so there is no movement at all occurs near where the wire goes into the diode body .
Nice one! Thanks for sharing Michael. I can remember a similar thing happening when I was a workshop engineer in the early 80's and field engineers used change the so called stock fault 910 ohm resistor in the Bush T22/T22A chassis and the heat from the soldering iron used to temporary make the actual faulty component (a BD2xx tab type regulator transistor, same package as a TIP41) start working again for a few weeks, until it eventually failed again. The 910 ohm fed the transistor base, and only a few mm's of track between them. All those set went wrong again, and came back to the workshop. The transistor always measured faulty in circuit but removing them they measured ok after being heated from desoldering. Replacing the transistor with a new one, a long soak test and returning to customer, they never failed again.
Yes I remember the 910 ohm resistor, it fed the base of the series pass regulator transistor and got so hot it changed color, glad you liked the video and it brought back memories of better days .
@@michaeldranfield7140 , Yes loved the video, a very useful tip. I still repair the odd TV that work mates bring in from time to time. I work in electronic and electrical machine training and education now to hnd / foundation degree level. However, I cannot resist getting my hands dirty on TV now and again 🤣
Bush T22
I remember those !!!
Crazy era of switch mode power supplies running all the time in standby mode.
Waste of power and just asking for short lifed components !!
Always a pleasure to see you work, and (I would bet) that you worked on the old valve CRT TV's too. Thanks for your videos, because it saves the hassle of scrapping them, and I have had an extra 10 years of use from repairing a Flat Screen. The only downside to their age, is that many are power-hungry, by comparison to those which are manufactured today.
Of course , I started as a kid repairing valve black and white sets and selling them for £5 , a lot of money back then .
@@michaeldranfield7140 Yes, me too. a lot of B&W sets failed due to Valves failure. I think that I used to place a 68 ohm resistor in the octal base (Heater). If all the Valves lit-up, you had pinpointed the faulty Valve. But I didn't progress to learn as much as you! I am happy to watch all of your YT vids. You are most definitely saving hundreds of Tv's from going to their final resting places. Thanks for your reply. Greetings from Sydney.
Its so wierd when simple components fail. I'd be looking for something more complex. Thanks for the tip.
Finding these problems with no service manual is the big challenge.
Simple when you know how. Thank you for a great tips.
Many thanks for watching
Absolutely great Michael.
Interesting tip. Thank you for sharing your experience!
Many thanks for watching .
Would you have any reapir info for samsung un40j6300af? Thanks for the great help with your videos.
sorry no , with most flat screen TV sets there is no service manual so fault finding after you have tried the basics is sometimes more good luck than knowing what your doing sadly .
Excellent stuff Michael. Muchly appreciated :)
No problem , many thanks for watching .
Thank you Micheal i am looking to use this tip today. On an inverter board i have one sm diode witg 24 volts on one side and 5volts on the other side. It tests okay in cct.Should i change it? Thanks Michael
definitely change it if its dropping more than 0.7 volts, even if it test ok as I think the junction can go high resistance when it gets hot.
Terrific keep it up......Thank you v much indeed Sir. Great job.
Great tip! They must use super-garbage parts.... I've always specified Vishay, Diodes Inc. etc. in products I've designed and never had a problem.... 20 years on still doing their job..
Everything seems to come from China now, no matter what brand it is unfortunately.
Great tip thanks Michael
Dear Sir, I do have some questions:
1. What do you think could be the reason for Vertical Banding, Grey Uniformity Issues, and Dirty Screen Effect (DSE) in modern TV's Panels?
2. From Longevity point of view, are Direct-Lit Full Array LED TV's better (Like Bravia 3, in which constant Backlight is ON) or the Mini-LED Local-Dimming ones (like Bravia 7, 9 in which hundreds or thousandsof LED's turn ON and OF and show varying degrees of Brightness to produce best Contracts, darkest Blacks and Brightest Whites, etc..).? Which among them will be the TV with longer life ??
3. I'm assuming keeping Brightness low shall increase the life of the TV.
Waiting for your reply. Possibly if you could make a video, it'd be great! Thanks.
Is there any particular brand that you have found to have better quality capacitors and components?
I know that more money =\=better quality.
Is there a brand that you know uses better caps and components? (I figure you've opened quite a few televisions and been able to see what kinds of components they use)
Thanks so much Micheal really useful tip
Comment about LCD TVs possibly having a fault like this is something for me to explore with my 4 blink Sony problem. Michaei I have a request re your Sharp LCD recent 2 blinks repair.Thank you
Please mentioning the value of ac voltage sources so we be not confused specially during power factor measurements. Thanks
All we used to do is replace the PSU in the field , when the call was booked the operator would follow a flow chart then send the panel suggested to my by box for collection the next day. sometimes they worked.
Thats the problem with most new sets now, no component level fault finding , just board replacement .
I tend to replace such diodes with the conventional wire ended version. Overall I find them more reliable.
when replacing with wire ended types be careful to bend the leads while holding the diode lead out with a pair of pliers,otherwise you can end up with the same problem further down the line, an intermittent junction contact .
Hey matey - thanks so much for the video (and the others that i have watched) Just wondering - where did you learn all of this, I have 30ish faulty DC to AC inverters I would like to diagnose and fix. Some are overheating and causing screens to black out... My knowledge is basic, but is growing by watching your videos! Thanks again - James of NZ
The forward voltage drop can rise in a diode if the ESR of the device has risen. Test it at a higher current. Also...if there are high frequency spikes, it's internal junction capacitance can make the device leaky.
As a footnote it is warming to see a REAL electronics engineer like me who has watched as his watched while the subject of his career passion turned into disposable junk. This is why I now work with industrial & scientific gear...
First time I came across high forward resistance diodes was back in the 1980s and these usually test OK when they have been heated by desoldering, its for this reason I think it's caused by a bad contact between the junction and the lead out and this is why now when I'm bending the leads on wire ended diodes I always hold the lead with a pair of pliers as there is no mechanical stress placed at the end of the diode.
@@michaeldranfield7140 Funny thing that...I came to a similar conclusion back in the "good old days" as well & do the same. We come from the same era when technicians were real technicians, a day when Philips service manuals were half an inch thick & cost a fiver from CPC & when the City & Guilds was a good qualification.
great videos i know a little bit fixed a few tvs but learning new things everyday thank you
Thank you for watching.
Interesting video. there are always 'common' type faults in every type of equipment. From tv's with no service manuals to the biggest computerised medical equipment where the service manuals stack to a height of 600mm :). I know I have worked on them all. One small observation, the diodes are a 14007 not I4007. The 1 indicated one junction device.
Just habit I have always referred to these diodes as IN4007.
Fantastic thank you very much indeed
No problem , thankyou for watching .
I have something going on like that, I'll check it out. But its reverse, TV starts up fine "cold", but then later doesn't. Sometimes switching the mains leads around makes it work again
A tin of freezer and hairdryer is what you need
Hi engineer i would would like to see 2wires of you meter i only see red ones
The diodes are added to the voltage regulator to reduce the power dissipaton of the regulator by a factor of 2 !
of course but they could have just fed the input to the regulator from a lower voltage source in the first place .
Have you ever seen an LED LCD TV where the screen goes black after a few minutes but still has sound and backlight? Stays black when powered on for at least a month, but if left off for a few months, starts up okay then, again, goes black after a few minutes.
cant say as I have seen that before and it sounds like its going to take a bit of finding its its intermittent , a hairdryer may be a good start , see if you can bring the fault on quicker .
@@michaeldranfield7140 The fault starts reliably. The problem is finding out what is normal to compare to.
It also seems strange that the issue persists for weeks even when unplugged and cold, as though a charged capacitor maintains the fault until it discharges.
@@atholmullen you could try a gentle tap around of even touching different wires and connectors with an insulated took , intermittent faults can be very time consuming to find .
Good tip. Thanks !
many thanks for watching .
Great tips as always 👍
Many thanks for watching .
Who needs a service manual when Michael is on the case 🙂
Plenty of things I have had to scrap due to no parts, no circuit ETC , this set is only one of the lucky ones !
Thanks for the tips!
Are you using a Pace rework station? Looks a lot like what I worked with back before I retired from communications. Now I only have an ols first gen Pace desoldering station.
BTW wher did you obtain the semiconductor tester? I see you also have several other testers made by the same company.
I use a Pace soldering station, this was £1600 when I bought it 20 years ago and in times gone by when I was super busy it was running 8 hours a day.
I have a lot of peak testers as I know the guy who makes them, he is only 5 mins down the road on the same industrial estate as me.
Have a look for Peak electronic design, Buxton, Derbyshire on the Internet.
Nice tip thanks
Many thanks for watching .
Niiiice... Thanks for the Tip Mike.
Thank you for watching.
Thanks for that hint - I hope this helps many people to get their TV going again.
Many thanks for watching .
@@michaeldranfield7140 How about I put this one into a playlist on my channel ? Something like 'Fault finding hints on modern electronics' ? If I stumble about more of these things I can collect more of this to help spreading this information.
@@ollisTubes of course you can , no problem .
Cheers Mike nice one man really good video 🤟👍 I’ve not had that yet on these, well I probably have but just board swapped it because I couldn’t find. I’ve had good luck replacing the flash roms on these when there’s no Pson signal, but the ir and buttons have triggering signals to turn the set on. Fixed a cheap nasty JVC hifi thing today with the class D fitted on to the same PCB as the SMP which I’ve never seen yet! Absolute junk this thing was, a shorted SR100 diode on the secondary was the issue 😎
Mind if I ask how come you have two atlas ESR meters I’ve had a ESR70 for a while. Atlas are a brilliant company very good ethnics.
Yes its a very common fault, surprising enough though its much more common with the DVD player mechanism where there are 3 diodes in series.
@@MrReeceyburger123 I have quite a few Peak testers, more than in the video , I know Jeremy who makes them, he is only 5 mins away from me at the other end of the industrial estate , I even have his very first transistor tester that I think he designed as a uni project , well before he set up in business .
@@michaeldranfield7140 ahh excellent information, I’ll keep an eye out for this. Thank you Michael.
@@michaeldranfield7140 ahh wow he’s a brilliant bloke I owe him big time, I use these at work and at home.
Great video!
Since 2008, I've had THREE flat screen TV's. A Panasonic 1080P Plasma. A Samsung 1080P LED LCD. And currently a MORESENSE 4K ULED LED LCD. All working perfectly. No faults at all in 14 years! ...... I also have a 40 year old SONY TRINICON Colour Video Camera, and matching 38 year old SONY BETAMAX VCR! You've guessed it, at a combined age of 78 years, both still working perfectly! ...... I also have a 43 year old JVC STEREO AMPLIFIER ... but this is getting boring? 😂😂😂
Old stuff was built to last and be repaired because back then it was so expensive.
@@michaeldranfield7140 True! Things now are built to a price, and are designed to fail! 👎
Great informative clips. Congradutions. My question is if the diodes you removed still test ok can you reuse them for the same application? It feels like an installation problem more than a part problem?
His diode tester probably doesn't put much current through the diode... More current would probably have shown it still being at fault.
Or like he said, heating it up temporarily "fixed" it and it would probably fail again later. They are cheap, so you may as well chuck em...
While this migh seem like a good idea I wouldn't recommend it, if it's failed once it could easily fail again.
@@michaeldranfield7140 Yeah - false economy - ...and no self respecting technician would want to court reworking (and good reputation), when the same 2c component fails again.
I have a tv which does just that. Must check that.
If they used genuine !N4007 diodes instead of crappy surface mount they would never fail but this is "progress"
At least with the leaded 1N4007 you could just unsolder one end to do an in circuit test , SMD is a right pain .
Looks like this might the problem with my LG Tv
its easy to test , just check the forward voltage drop .
weldone boss
Many thanks for watching.
For those doing this, make sure your diodes are facing the correct way as well, as they're omnidirectional
Unidirectional?? Polarized.
I’ve never heard of an omnidirectional diode. That’s not a diode’s design.
A diode that conducts both ways? Where can I find those they sound really useful
next time - let's film the entire footage of removing and then replacing the resisters and then play the results .... the way is is filmed -- you did replaced the parts but the next scene shows the tv working -- not knowing if it was the actual bad parts as the culprit ... it just makes sense this way ...
great video but needs to show facts thereafter ....
I get where your coming from but I think most people watching youtube are just looking for a quick fix and not wanting to watch an hour plus long video .
I think the real problem here is not the diodes at all. The real problem is a cold solder joint. All you would have to have done is reheat the joint with some flux and that should have fixed the problem. Diodes don't fail like that and then fix themselves.
I've seen this happen to the older through-hole 1N400X series diode, but only from many years of 24/7 use, and mild overheating. But I don't see any evidence of that on your TV board. I guess this is just a bad batch of them? Shouldn't happen.
I first came across this problem in the 1980s on a TV that had a whole load of leaded diodes like 1n4007 that were painted silver so it may have been a bad batch then
But I'm pretty sure on leaded diodes it's caused by a poor junction to lead out most likely caused by stressing the junction bending the wire and for that reason I only bend diode wires while holding in a pair of pliers. But as you say heating and cooling plays a big part in the failure mechanism.