Rank Bush Murphy Z718C Chassis vintage colour TV set from 1977 restoration. Model MC6301.
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- Опубліковано 17 лют 2023
- Filmed over several months and over 100 video clips later so there may be slight duplications and mistakes in the video , I manage to get a Rank bush murphy Z718C chassis colour TV set dating from about 1977 back into working order , I am very grateful to John Joe for supplying me with this rare set and below is a link to the Vintage Irish Radio TV youtube channel which I strongly recommend you subscribe to if like me you are into vintage electronics , I have been repairing TV sets for a big part of my life and repairing this TV transports me back 40 years to a time of very happy memories when been a TV engineer made you a good living.
And before anyone says , yes there was a big mistake in the video , I forgot this set has a mechanical 4 push button tuner and NOT a varicap which I mistakenly referred to in the video .
Below is the link to John Joe at the Vintage Irish radio and TV youtube channel.
Many thanks for watching .
Michael Dranfield. 18-2-2023.
@IrishvintageTVRadio - Наука та технологія
The TV engineers dread, multiple faults and previous tinkering by someone who didn't know what they were doing! Well done Michael, a joy to watch you work.
That's always a problem when your trying to repair something that's already been looked at, got there in the end though !
@@michaeldranfield7140 Theyre difficult to diagnose because in the early days of solid state televisions were extremely complicated internally, however the late 70s sets were the best of the lot and had the best picture too, were like tanks
Hi Michael, just to say a big thank you from an ex TV technician of that era, it brought back so many memories of a long gone time when repairing equipment was a satisfying, and profitable, career. I always enjoy your videos and this was definitely one of the best. I realise the time it takes to run this channel and very much aooreciate it, thank you and regards.
Glad you liked it , it was a good trip down memory lane for me also to a time when stuff was designed to be repaired .
I remember these, in my apprenticeship, as I recall they could be Troublesome, to be polite, these were in the rental section and worked hard, we were glad to see the back of them,
The service manual shows a single stick rectifier with 25Kv overwinding so I guess its no wonder they were un reliable, but this set was fitted with what appears to be a aftermarket 8Kv overwind and Tripler combo so giving up was not an option .
Nice one Michael-your seemingly infinite knowledge is as impressive as your gift of instruction. Thank you for your efforts and your wisdom.
Glad you liked it , I am much indebted for John Joe for supplying me with these sets , he actually gave me 4 sets but the other 3 I have not looked at yet , it was a very interesting journey for me bringing back very happy memories of the 80 s when I was repairing sets like this every day .
Michael….
You have the patience of a Saint !
Excellent diagnosis, thanks for sharing your vast amount of knowledge 👏👏👏
40 years ago I would have had this set going a lot quicker than that but im starting to forget stuff now so you have to have a lot of patience and a service manual in order to repair vintage stuff .
Absolutely fantastic! Great viewing.
Thankyou for that .
Hello Michael, I was getting worried when I saw the state of the tube socket as I thought the picture tube would have had many hours on it but what a great picture. I really enjoyed your methodical approach to sorting it out, very interesting and well done. Thank you for posting.
It was at the tube base socket I was wondering if it was game over until I remembered they were a common cause of trouble back in the 80 s and maybe still had them in stock .
Thanks for uploading, and really enjoyed this
Some intelligent diagnostics and persistent circuit tracing. Even some calculation involved. Thanks for demonstrating the professional approach to a complexed repair.
couldn't do that with a modern flat screen TV , take me back to the 80s any day .
Reminds me of a 1984 Advent 3 crt projector. Customer took it to shop after shop for an intermittent problem. Finally he got tired of messing with it. I gave him $100.00 for the project. Was a challenge to find but like you I kept after it. Repair was after all simple. Changed out the 3 CRT sockets for ceramic. Like magic all the intermittent issues went away. I have usually found many problems are simple to fix.
Good job on this one..
intermittent faults can be very time consuming to repair and on newer stuff its hardly worth the trouble but with a new LOPT fitted in this set failure was not an option .
CRT tv's from the 70s and early 80s had a certain something about them, with the corona discharge from cooking steam and the fun of many controls to produce a good picture. Today's modern look a de tooves (phone jacker) have nice definition and clarity and no lopt to fizzle and go PHUT ! like my old Sony trinitron did. Glad that you still have the opportunity to enjoy these old sets and bring it to us here to enjoy once again.
Back in the 70 s and 80 s TV s were so easy to repair, clear well laid out schematics and if you were stuck on a fault just ring up the manufactures technical department for more in-depth help, nothing like that exists now , everything is disposable and no ones bothered , how things have changed, I'm so glad I lived through the early days and repairing stuff like this brings back so many happy memories .
These sets takes me back to my younger days in TV repairs.
You can spend many hours replacing the known weak components, many failed
due to the amount of heat these sets generated.
Lopt's were a weak spot on many brands, the popular ones we kept instock knowning
that you would need one sooner rather than later.
One of my biggest problems is back in the day LOPTS were an expensive item so I very rarely kept these in stock and usually only got them to order so I don't have any new old stock ones now like I have other stuff, the reason I so wanted this set to work is it had a brand new LOPT already fitted and as long as the LOPT and scan coils are OK there's not much else that cant be fixed or modified to work .
@@michaeldranfield7140 Ahh the good old days, back then we knew the most common faults before we took the back off.
And LOPT's were a very well known weak spot, i wish i had a penny for the number of Philips 210 chassis LOPT's that i replaced
these and a few others we kept in stock, the others as you say were just too expensive to keep on the shelves just incase.
Other components like capacitors and resistors could be replaced at a much lower cost.
These days they only want us to replace complete boards, but i still try to go to component level if i can.
I found this one of your best videos. You dealt with so much and had the patience to keep going .
Did take a while but I got there in the end , I couldn't give up on this set because it had the new transformer in , the biggest worry with any vintage set is the LOPT because if that's dud your not going to find a new one .
This is just a brilliant insight into faultfinding a mixture of stockfault experience and expert detective work. Thankyou.
this is how easy it was to repair sets back in the 80 s , stock faults were an easy source of money as models continued for years , unlike today , different models coming out every few months , you never see the same set twice , take me back to the 80 s any day, so many happy memories .
Hi Michael, seeing the inside of that TV has brought some great memories back. My father used to own a TV rental company and we serviced loads of these TVs 😀
Very popular set in its day, this is one of those sets I thought I would never see again , glad you liked the video .
Hello Michael. I really enjoyed this video. It reminded me of my time working on old black and whites set in the 70s. Thank you for making all your videos. I look forward to the next.
Mike Spellman. Auckland New Zealand.
Many thanks for that , I do have more vintage TV sets to do videos on but just a bit short of time at the moment .
Superb video. Cheers for this.
Many thanks for watching
I love watching your videos. That was so much fun. It's like I went on the journey with you as you went through the schematic. And watching the TV come alive.😊
Took a lot longer than I expected as I was doing this on and off in-between making a living , there's not many schematics I don't have , finding them is the biggest problem !
Exactly
Good luck
Good application of logic, plus familiarity with the fundamental operational characteristics - not to mention having the actual circuit diagram and replacement components!
This is how easy sets were to repair back in the 80 s , not much chance of repairing a modern flat screen set to component level now , no service manual exist for most sets, no individual components , only a new board , all designed of course just to sell you a new one .
Really impressive Michael the problem solving involved here.
Looks impressive but back in the 80 s most sets were so easy to repair , its only in the 90 s when sets were more software driven they got harder to repair .
This is one of the best detailed videos you have done
Never liked these sets but now with your perfect explanation
Well worth looking out for one
Excellent as usual
Wasn't intended to be this long though ! this should have been an easy fix .
Thanks for the time taken and determination. Many would have given up. The 910 ohm resistor brought back.memories. I remember it being a weak spot on T20 and T22 chassis.
I always favoured the T20 and T22 over the Z718 back in the 80 s and also the T26 so this was an interesting journey and brought back a lot of happy memories .
@@michaeldranfield7140
One really handy thing about the T20/22 was the small rectangular PSU in the bottom of the set. It was easy to get out and send away for repair. I was never clever enough to diagnose switching power supplies.
Well done, impressive analyses and rectification of somebody else's tinkering. The burning EHT resistor confused me, especially becoming warm when the cap was disconnected. "When CPC was a really good company" made me laugh, I concur.
It was the burning resistor that gave the final fault away , back in the 80 s CPC was a major supplier for more or less every different manufacture for people who did not have direct accounts ,you could get anything you wanted from CPC , how things have changed , its more like an Argos retail outlet now .
What an head scratcher that was,some serious fault finding there,well done,great picture too.
This is always a problem when you dont know the history of something and someone else has already tried to repair , but I got there in the end .
Michael, Thank you for the great effort to make this video. You have a great skill for explaining what the various components do within the circuits and where they are in relation to the circuit diagrams. This is very helpful for us hobbyists. You have such a vast amount of knowledge and experience - thanks again for sharing it!
I am starting to forget things now though and usually need to spend quite a bit of time studying the schematic to jog my memory , its a long time since I repaired sets like this .
Great job there Mike. I served my apprenticeship at a RBM dealer and I recall that the Murphy version of these sets came with a rather courageous five year guarantee ! The RBM technical rep told us to replace the 910 ohm resistor with a 1kohm 1 watt resistor.
Watching that brought back many memories,like you I've probably not seen one since the mid 1980's.
I liked the RBM stuff , even the T26 which was Toshiba designed , I don't know what happened to RBM , I know the Bush name is still around , now owned by Argos but its nothing but just a name now .
@@michaeldranfield7140 Our field engineers used to replace the 910 ohm on these and T20, T22 etc. However, a few weeks later, after replacing, the set would fail again and they used to bring it in to the workshop for repair. In the workshop I always found it was 4VT20 the 2N5296 was faulty. The heat from their soldering irons must have temporarily got 4TV20 working again for another few weeks, until it failed again.
@@marksntl7632 I have come across this quite a few times and still do today , you find a faulty diode or transistor doing a cold check and then when you remove it it tests ok again .
That was a epic repair Michael 👍. I seem to remember those front slider controls only covered part of the range such as the sound not going completely to zero but I didnt see to many in the day so could be wrong , but I do remember those tuner units had those plastic nuts that split like the A774 mono sets did a few of them in the day . Good to see it back in working order I'm sure Jonjo will be pleased as well .
Not had the front controls out yet , got to find a speaker first and there's also a foot missing to source under the set , but yes it was a good result .
Your a pretty smart fellow!
Was, you mean , cant fault find to component level on new flatscreen sets as there is no service manual for most sets , its just whole board replacement .
@@michaeldranfield7140 - It was meant as a compliment.
I know it was a compliment, my point was I was a lot better at fixing TVs in the 80s when they were designed to be repaired, everything now is designed to fail and be as un repairable as possible.
@@michaeldranfield7140 - I find the new sets to be much simpler and quicker to fix, but, hay, that's just me.
@@tubeDude48 anything is simple to fix if you just swap the whole board but what's the fun in that .
My goodness what a marathon. I'd have given up at fault 3. Great work Michael
Very good detective work
giving up was not an option , not when you have a brand new LOPT fitted .
I remember the z718 with the line incorporated psu mni times it was the lopt with shorted turns. Thanks for the video Michael excellent
A faulty LOPT is the biggest worry with any old TV set, the fact this set had a new LOPT already fitted made giving up not an option .
Enjoyed that very much, so interesting.
Many thanks for watching .
Those tops and grass really show off the set’s colours. I’m just amazed at how you get through all these faults.
Yes the picture was even better in real life than it showed in the video , these Toshiba blackstripe CRT s were superb compared to the Mullard stuff that had a very limited life .
Yes I I failed to mention that almost no LCD can reproduce the colours a CRT produces properly.
Thanks for the video, I always enjoy them, it was great watching how you worked through the problems
It wasn't meant to be this long , I thought this would have been an easy fix !
As marathons go, you certainly just ran one. Goes to show you can't assume anything when taking over from a previous repair. As you said, back to basics with an EHT fault. Bingo. Dead trippler. As always a GREAT watch, and wonderful trip down memory lane. We didn't have the Bush range in New Zealand, but Thorn and AWA always kept us amused 😉.
Cheers
Pete'.
Apparently Rank Bush Murphy were big in Ireland back in the day , you never see sets like this in England any more so it was a real pleasure to work on another one after so many years , had this not have already had a new Tripler fitted that would be the first thing I disconnected , so I can only assume the incorrect heater winding to earthy end of the tripler must have damaged it .
Brilliant !
Many thanks for that , I need to get back to this and get it finished .
The best yet Michael, glued to the chair stuff. Thoroughly enjoyed watching it, must be one of the best repair videos on UA-cam.
Regards see you soon
Dave. 😀
Lots of people said the same , this video was never meant to be this long , I expected this to be a quick fix !
Liked the methodology, also took be back many years when I looked after Sony CCTV monitors, they used odd kick start circuits. Fault easily proved by a 12v battery across the capacitor.
Some early Hitachi sets used same start up method , I use to just bridge the cap with a resistor .
Another most excellent video Michael! Thanks for sharing! Another great trip down memory lane for me 😀I still have some of those trimming tools too, in my TV toolbox. They have proove very usefull on many makes of TV over the years 🙂
I was lucky to find that trimming tool considering how huch stuff I have!
Ojnoj covered my mum and dad's first Bush from radio rentals in 1957 which lasted 10 years till replaced by. A DS Baird monochrome. He also covered the DS TV191 that I got from the dump which gave a fantastic picture. I think that is why they chose Bush as their first non rental bought from Comet. I was a 26 inch Bush Arena with ultrasonic remote and touch varicap tuner. That had your chassis and a Toshiba tube I think Rank Toshiba had some sort of partnership in Plymouth. The Bush Arena was great it lasted over 10 years till the Tube started to fail.
I have a 26 inch rank with ultrasonic remote and teletext but never got round to looking at it yet , you are correct there was some sort of RMB/Toshiba marriage as there was a set, T24 chassis I think it was which had a Bush cabinet and badge on the front but inside it was a Toshiba set , back in the 70 s my parents only rented , we had a Thorn 1500 which looked ok until one day it went wrong and the rental guy took it away for repair and left a Bush loan set in its place and the contrast on the bush was far superior , that's when I realised how bad the Thorn was !
I have very fond memories of radio rentals , I use to climb into there industrial bin as a kid when they had closed , looking for TV boards , never found anything of any use though !
really enjoyed this , I paused it a few times and looked up different terms you used .
Many thanks for that , more stuff coming soon!
Excellent video Michael, thank you for taking the time to make it.
Many thanks for watching , I didn't expect the video to be so long !
Thanks for the journey Michael it has been very enjoyable. In the making
Thankyou for that , it was a very enjoyable journey for me too , transported back to the 80 s , happy days , now long gone sadly .
That was good! And I mean really good!! I enjoyed every minute of it.
I have, somewhere, a Bush colour telly of about the same vintage. I got it from a forum member who spent some time and effort on it. It has sound, it has picture, but there's a shed load of other problems with it. Convergence is, well, it doesn't, actually. I need to get it out and have a look at it. It's been in storage for years, so I have no idea what it can or can't do now.
It's always good to see another set brought back to life, especially when it reminds us of a different time, or people who are no longer with us.
I'll tell you now, I would probably have given up on your set a long time back. It's those quirky little bits of circuitry that would lead in to knots, especially those little "kickstart" capacitors. I would most likely have sat there looking, and wondering what they were for 🤷🤦. Just give me a bit of hot wire and some high voltage, and I'm happy! 🙆
Giving up was not an option considering this set had a brand new line transformer fitted , as long as the LOPT and the scan coils are OK there's not much that cant be repaired or modified to work , I even made a Tripler for a Decca set a year or so ago !
I am very much indebted to John Joe for giving me this set and a couple of others I have not looked at yet for the very reason you mention , I'm a great sentimentalist and repairing this invokes so many happy memories of the 80 s when I first opened a shop with my two business partners that both passed away 5 years ago .
I am really enjoying your videos. Your knowledge of circuit tracing is outstanding and a pleasure to watch. This one was quite a challenge.great job.😊
What a journey ? 👏🏻
It certainly was but I got there in the end !
Fantastic video and thank you for going into such detail explaining the faults and you have done good graphics tying in the circuit diagram. A very interesting post wekk done. Nigel Jefferies
Not many service manuals I don't have , finding them is the biggest problem ,, I have thousands , I'm so glad though I didn't throw them all away , never thought I would ever be repairing sets like these again but its been a very interesting trip down memory lane and invoked a lot of very happy memories .
Educational and helpful for me, thank you.
' have to old tv sets given to me just lately.
look after them , old TV s like this are getting very hard to find now
What a journey. Well done. Ye na yer onions bonny lad.😉
no option of giving up with a new LOTP fitted .
Nice Video
Many thanks for that , 1977 retro.
my word what a lovely picute, you are a true master of your craft your knowledge of these old teles is just awsome.
WAS a true master you mean , cant do anything like this with new flat screen sets , no service manual , no parts only spare boards,
ah memorys, my dad had the 18inch version with the stick eht rectifier in a damp drafty 1900,s built house. i could always hear the corona discharge entering the room. i was to young to know what to do other than ipa and a hair dryer.i never realised that its not so different to the a823a design wise but then i didnt realise it was so old. it was striking how vibrant the colour was .the only faults that he had was the e/w diode shorting as you say. most reliable set we had back then. he got a philips g11 after that --constant problems and a horrible dull pale picture too
John Joe gave me a 18 inch set also but there was some parts missing out of it so I don't know if restoration will be viable or not , according to the service manual this 22 inch set should have had a stick rectifier so I can only assume the lopt/tripler combo was an aftermarket replacement part , but yes , this wouldn't have been as good if it didn't have the Toshiba blackstripe tube fitted .
Excellent video, loved every minute of it. My parents had a Bush that was very similar to this and my dad had worked on it a few times. I remember the boards looking as they do here so I'm guessing it was the same chassis. But it had a 6 channel tuner and the volume, brightness, contrast and colour controls were knobs rather than sliders. It developed a fault in the mid 90s with a hissing sound and we moved house shortly after so it never made the move with us.
Definitely a mission, that one. Well done for determination and persistence. I must say, for some reason, during my years in the trade I had very little to do with RVM sets. In fact, all I can remember was the A823 chassis and their 'orrible decoder. Worked on most everything else but not RBM. Given the questionable complexity of that thing, I can't say I'm too sad at having missed out on them. Looks like an opportunity to deploy as many semiconductors as possible. We'll done for batting on, if I had spotted green disease, I would have scrapped it.
I did quite a bit with these sets back in the 80 s , the very last one I ever repaired was early 2000 s , a T26 which was just a Toshiba set in a Bush cabinet, no chroma due to a missing line pulse to the decoder chip, o/c resistor , it belonged to my accountant and it was old in the 2000 s , never seen a RBM set since and didn't think I would ever again so it was a great pleasure to work on this set .
A really nice thought process, although I wouldn't want to pay the invoice!
this is the problem with repairing any vintage stuff , its a labour of love , you never get your money back but as this was my set and not a customers it didn't matter , I would just take a look in between other paying jobs .
🔊Spot on my friend, loving the longer video format. around 1991 we had a BUSH tv similar to this, to be honest even to this day it had the best picture ive ever seen on any tv, and for colour accuracy and dynamics even beating the new OLED crap, these were stellar televisions with an awesome colourful bright and stable picture. we used to play the sega master system and mega-drive on it, as long as they didnt have a mullard tube, as those went weak in about 5 years, the toshiba crt's were far superior, yes those slider controls dates these sets to the mid 70s as they didnt use them for long as they were so unreliable because of them being dust and moisture magnets. and of course nearly everyone smoked in the 70s making their lifespan even shorter. i used to use an ordinary lead pencil to revive those slider pots
I didn't intend to make a video this long , over 100 clips shot over several months in between trying to make a living ! the Toshiba blackstripe was indeed a excellent tube as you say compared to the Mullard stuff that only lasted a short time , in the 90s I was selling Samsung 14 inch portable sets fitted with a blackstripe for £179 and the picture was far above most stuff on the market , still got the master system , mega drive and mega CD player my son use to play on in the loft , it was however a bit advanced for me I grew up with an Atari 2600 but I did like the sonic the hedgehog game on megadrive .
@@michaeldranfield7140 Michael what a legend, the original sonic and mario games were unbeatable! i used to collect those nintendo game and watches years ago, i highly regret parting with them, they were epic.
The japanese crts were amazing, especially the trinitron and diamondtron stuff from mitsubishi
We need to open factories here in the uk now were out of that shitshow that was the EU dictatorship. new crt assembly plants
china are still making crts so we should!
Just been watching this again, and I'm just thinking to myself, I hope this TC-2110 doesn't put up a fight like this!
I have a fair bit to do this year, getting accomodation sorted out, getting my state pension sorted out, and hopefully getting my workshop/cabin sorted out.
Somewhere in between that lot, I want have a look at some of my old tellies and things, and settle down to a retirement where I can enjoy some of the things I thought I was losing touch with.
same here and this is why I need to start stock pilling stuff for my retirement , I couldn't imagine a life without electronics, just need to win the lottery so I can get a big house and fill it with old stuff !
@@michaeldranfield7140 Ah, the lottery. I keep buying faulty tickets - They either, don't work at all, or don't work very well! I could do with a good win, then I could buy a nice place where I could bury myself in vintage kit!
Yet another extremely interesting and exciting video. Thank you for sharing it with us and for taking the time to make the video. So many small issues that stopped the set from working. I found it fascinating to see how many individual component circuits there are in a TV like this. Please could you do a video explaining the various sub-circuits in a TV like this and how they interact with each other to make a complete television?
I have more vintage TV stuff in the pipeline but its a long time since I repaired stuff like this and I have to spend quite a bit of time studying the service manual first to jog my memory on how it all works as I have forgotten stuff myself, also back in the 80s most sets had there own common faults which you would get on all sets but once again Its all down to how much I can actually remember .
Great stuff Micheal, lovely video.
A most excellent set John Joe ,will go well in my collection and I cant thank you enough for letting me have it .
@Michael Dranfield No problem at all, couldn't of gone to a better home.
@@IrishvintageTVRadio Hi , JJ , Made a start on the white Toshiba portable yesterday and that's turning out to be another more difficult than I first thought repair !
@Michael Dranfield I thought the little Tosh was going, they were bullet proof!!
@@IrishvintageTVRadio It was , for about 2 minutes !
just setting the height and the colour went off, checked some parts then time to go home, switched it back on again in the morning and now the line and frame sync have disappeared .
what a cracking telly ! great work michael really enjoyed this one
Many thanks for that , I didn't intend the video to be that long !
Hi Michael, talk about red herrings. Well done!
Got there in the end !
Great video Michael but you had me confused because you were using at least two different circuit diagrams! One (at about 7 minutes) showed the +12v regulator powered by a +30v line, the other (at about 16 minutes) showed it powered by a +32v line. Also later on you have two different circuit diagrams of the tube - one with a 68k EHT resistor and the other with a 10k resistor in the EHT lead. Must have been from slightly different models and probably because the renovation was spread out over a long period. Must make the job harder!
there can be more than one circuit diagram for the same model as a lot of older sets production ran for a long time and many different modifications were introduced .on top of this this repair was filmed over many months so I could have been using different diagrams for very slightly different versions of the same chassis .
Very interesting video and took me back to my time repairing similar TVs in the 80's. It is frustrating when a fault clears and there is no obvious reason. I don't know if it was the possible cause or not but noticed what looked like a thin stray filiment of solder between pins 13 and 14 on the IC at 23:32. After you had tested and replaced the capacitor at 25:38 it was no longer visible. Maybe you knocked it clear when connecting your scope probe? Spend my time now in retirement restoring old valve radios and adding (removable for the purists) BT to extend their useful life as the radio stations shut down. Thought about having a go at some old TVs and then remembered my back.
who ever did this work never had this set working as there were so many things wrong , for a start the focus control is missing !
However this set will be back on youtube in the future as I have managed to find some spare parts and the correct focus control, the last part I need is a speaker , there could well have been something stuck between the IC pins as this set has had considerable work in the past .
What an interesting video Michael. I was intrigued at the beginning of the video when you stated that this Z718 had a tripler fitted as I remember the original LOPT had a huge overwinding, 25kV output and was very expensive. Like the T20, the Z718 used some novel startup circuitry and I found the servicing articles in 'Television' extremely helpful when it came to quick and profitable repair work.
This is correct, the service manual shows a single diode , I cant remember now as its such a long time ago since I last repaired one of these sets but I would assume the transformer/tripler combo with 8Kv overwind is an aftermarket modification possibly as the 25Kv overwind was a common source of trouble back in its day .
Great set i had 18" tabletop model for years much better than the old delta sets
of the time
Yes John Joe also gave me a 18 inch set with lift off plastic cabinet but there was parts missing out of it so I don't know if it will be a viable restoration or not .
New to your videos, enjoyed it very much..Leo
more vintage stuff in the pipeline soon .
It looks so familiar but as you say "it's such a long time ago" I can't remember any of the faults. Maybe one of the RGB transistors easy to find easy to fix swap two of the leads over to see if the tube was OK then change the transistor & remember to put the lead back on the right colour. Thanks.
Some Polystyrene capacitors become internally intermittent after being exposed to moisture, and recover when direct heat is applied, had a few over the years.
That would explain the fault I had then , I didn't know that and if I did once I have forgotten anyway so I am going to replace that cap now , many thanks for that .
@@michaeldranfield7140 These Polystyrene Axial Capacitors used to go faulty in thorn 3000 etc. too, even with normal use and not being stored. Sometime o/c sometime even short circuit. The heat from the soldering iron would very often make then appear ok when removed and measure ok once removed. So a good idea to change it out for a new one
@@marksntl7632 Yes I have made a mental note to replace this capacitor , got to get a speaker first then may make a part 2 video follow up, I must remember this too , just got a Thorn 3000 or 3500 set in , not sure what it is till I get the back off .
You can not beat a CRT for colour accuracy and contrast. If they made 40" HD CRT TVs I would buy one hands down.
I wouldn't want have to lift and deliver it though
@@jonathaneastwood2927 This is true but then some big flat screen sets still need a two man lift unless you have very long arms .
CRT was superb technology as you say , sadly long gone now though.
in line picture tube with dynamic passive convergence looks like the linytron sharp picture tubes
this is correct , very few convergence adjustments , its good to know that someone else remembers the Sharp Linytron sets I have one of these also on my channel but not got round to finishing it yes so no part two as yet !
just found your channel and subbed,. thanks for your passion,. nice video,.
Glad you like it , I have loads more stuff to do but just not enough hours in the day to do everything .
You should try a thermal camera to see what is getting hot. It is a fast way to identify shorts. These cameras are getting really cheap these days.
yes I can see how it would be useful but I wouldn't want to spend on something I may only use very occasionally .
@@michaeldranfield7140 I saw the other day a tiny adapter you plug into your phone to give it heat detection seems like it was very cheap. Low resolution but it was a tech guy that does your kind of work it was good enough to quickly see what got hot. Not saying you must get it but it is just the ticket for some things.
Hi Michael, nice job a true labour of love! I thought those black and white connectors had locator pins in different positions to prevent accidental insertion?
they do
They might well have , I just didn't want to take any chances , until I realised they were colour coded that is !
@@michaeldranfield7140 Nothing wrong with being safe.
Just this minute has a similar issue with a Toshiba radio cassette, both the audio head and motor power connectors are identical. Wouldn't be as impressive as getting the TV connections wrong, but not sure the tape head would be too fond of 9v DC.
@@adamdavies163 in the end it turned out the two connectors were different colours, but in the past I have managed to get connectors mixed up on other stuff .
This Murphy TV is the first one I remember my parents owning, so if they bought it in 1977 I would have been around 4, and this is the first time I've seen one for something like 35 years. So many thanks for uploading this as I've been trying to work out for years what model it was and now I know. One thing I remember is they had this set when Channel 4 launched in 1982 and we were already using the IBA2 button for the VHS recorder, so the only way to watch C4 was through the VHS due to the lack of channel buttons on the TV.
Were those convergence controls on the back of the set supposed to be adjusted by the user? As I remember my dad at least once adjusting something on the set in that area but don't remember him taking the back off, so I'm guessing there must have been holes to access those controls.
Nice my video has been able to bring back treasured memories for you, The convergence controls are not suppose to be adjusted by the user but Rank included a special tool clipped to the chassis for adjustment so if the tool was still present and had not been kept by the previous service engineer like I use to do then they could be adjusted by the user .
chassis looks like a t22a at first! i had one for quite a few years in the early 90s, it was a chuckout i resurrected , had no colour fault,
i have a spare t22a power board lurking around somewhere...
hmm, i think the t22a used same 910 ohm resistor.... my t22a had problems with the 12v supply
i also had another t something chassis model with power board similar to that z718, but its lopt didnt have a tripler just a big long diode, it generated the 25kv or so directly, like shown in the diagram....also had an early TI teletext board , with ultrasonic remote, maybe one of the first teletext models?
The back of the set also looks like a T20/ T22 , in fact I thought it was a T20 at first .
@@andygozzo72 Yes you are correct , the same 12 volt regulator circuit was used in a few different models
so best guess at the eht series resistor burning up is the tripler sending unrectified eht to the anode cap and the aquadag cap saying no thanks ! if thats right its really wierd you still had 2kv of suposed dc showing on the eht meter? i assume ac on top of a dc bias of 2kv?
AC to the CRT is what you would have thought but I had a 2Kv DC reading that doesn't make much sense , at first I just assumed the EHT lead was screened like some sets use for additional smoothing and was leaking to ground and as the tripler was new and appeared to be part of the lopt modification I never even gave a thought to it been faulty, I wonder if it was damaged by connecting the heater winding to the earthy end of the tripler ?
haha,that tripler was used in a microvitec cub monitor
I think the green ones I have were used in Grundig sets , I remember Microvitec, I had shares in them , they they went bust .
@@michaeldranfield7140 probably both and some other sets,but i can tell you for sure that part is in cubs,if you look at the service manual the part is mentioned,its a common failure even now,i think the person who started microvitec used to be with thorn?
tv horizontal oscillator frequency i think was 15625
correct 15.625Khz
@@michaeldranfield7140 heaps of repairs here in Australia valve preamp amps radios
Was I seeing things? You seemed to have a different schematic every time you put it on camera? e.g. 30V then 32V on the intermediate supply and 68K to 10K on the anode resistor.
Not seeing things , this video was made over several months with over 100 video clips so yes there were many mistakes , did you spot the mistake where I looked at the schematic and said I wont be able to power the set up with the line panel removed because there would be no supply to the varicap tuner ? I then realised I was looking at the wrong model as my set had a mechanical tuner fitted .
ive had that with polystyrene caps ,the soldering iron heat brings em back, (had that with noisy /dead to92 ,s too) wouldnt trust it now
yes , someone else said exactly the same thing , I am going to replace that cap now .
Very interesting diagnosis - thanks Michael. Just out of interest, what does an anti-breathing circuit do?
Connected to the earthy end of the EHT tripler and automatically reduces the beam current in order to keep the size of the picture constant regardless of EHT and power supply variations which can occur when a scene transitions from light to dark .
@@michaeldranfield7140 Many thanks for that! I've noticed that effect on some sets.
So is this set where murphy's law comes from ? 😁
must be , got there in the end though !
I havent seen the previous video, can you elaborate about leaving the flyback to dry out ? I only ask because i found a tv in a back garden last week, looked like it had been there a long while, i got it running , but the day after the picture started going funny, i couldnt get the picture to focus on the flyback, now i have no image apart from a black screen, asif the tv is on ac input, i cant find anything wrong apart from the flyback smells of burning. Im wondering if the lineoutput/flyback has died ? Theres still high voltage but maybe theres not enough and some windings have burnt out maybe due to the damp? Any advice welcome , ive sourced a replacement flyback
because the overwinding of the transformer is working at such a high voltage any moisture in the winding will have catastrophic results and that is a mistake I made on another vintage TV I burnt out the transformer by powering the set up, what I should have done is removed the board or even just the transformer and left it in a warm place for a few months before powering up and this is more likely what has happened to your set .
However saying that in your case I would have a good look at the focus pin on the CRT base socket because any moisture or corrosion here will have the exact effect you mention .
@@michaeldranfield7140 thanks for your reply , i had cleaned the focus wire because it was oxidised on the end , its all clean and making contact but it didnt solve the issue , im waiting on a lineoutput being delivered from ebay. Really hope i can get this tv going again, my dad who used to fix tvs back in the 90s mentioned it could be the crt itself thats died . But the picture was brilliant one day and then poor, then non existant the next day so im not sure . Thanks again
This set seems like an absolute pain in the bum!
Part of the problem is you don't know what someone else has already done and things that have not been used for many years always throw up more problems they didn't have when the set was put away
that looks like Philips chassis
They are not identical! Guide pins are on opposite sides
I have no doubt you are correct , I just didn't want to make an expensive mistake , then I realised they were two different colours .
Horrendous sets - The A823 was a much better chassis and so much easier to work on