Thorn 8800 chassis vintage TV set from 1977.

hi guys and girls on youtube welcome to my channel in this little video we're going to be taking another trip down memory lane this is another tv set a vintage tv that i've acquired off a friend of mine so let's pick up the camera and turn it round so i've got it well under wraps there um i'll give you a clue it's a thorn and it's from 1977 approximately so let's just lift the cover and have a quick look and there we go it's the thorne 8800 chassis and it's a ferguson model three seven three eight and it's obviously got um ultrasonic remote control but i don't have the remote for it but there's always a possibility i might come hold of one and because my friends probably got the remote he just doesn't know where he is it's like he's a bit like me um he's touched tune and uh if we take a look around there you can see the fablon's just starting to peel off because he's actually kept in his cellar so let's turn it around and have a quick look at the back first right so that's the back view uh he's obviously very dirty because he says he's been standing at least 25 years if not even more we'll take a look there the model plate ferguson 3738 uh if we move down there that's the um camera's gonna have to focus now that's the um i think it's a two amp cut out um if we move around here there's actually a sticker on the side and it says um aerial installation by pennine aerials so that possibly has been on it since it was new now my friend says this was working when it was laid up but obviously after 25 years there's bound to be something wrong with it now and i've noticed on the top there's a little sticker there and it says on it well i don't know if you can see on the camera um let's just have a look it says on it a51 120x so that's the tube um it says that's been replaced the eht tray and the line output transformer i think it says replace i hope it doesn't say removed hmm anyway so what we'll do now is we'll just pop the camera down and we'll take the back off and have a look inside right well that's interesting i've got the back off and there's a little diagram there for setting up the convergence and also there's a layout of the panels there but more importantly there's a sticker there that tends to suggest this might have been on rental um that rumbles at some time in fact it's dated there first to the seventh 1983. now you can see it better now and it's got uh engineer's signature e shenton so somebody who was watching youtube might have worked for rumbles might you might be watching your own name on youtube um anyway let's have a quick look inside the tv i've spotted another very unusual thing um now i can't because it's such a long time it must be the the 19 mid 1980s last time i repaired one of these and they were getting a bit old-fashioned then um i don't remember these been fitted with a toshiba tube um and i did say on the sticker on the top um it tends to suggest the tube's been replaced and but if you move to the other side it does appear to carry the correct um thorn logo for the tube so i'm not really sure what's going on there um i've also checked down there the line output transformer uh you can see it has been replaced obviously with the second hand one because you can tell by the soldering and the transformers all dirty um but let's uh let's have a quick look around that's the time based panel uh focus control tube base uh that's some of the convergent settings on the delta gun and there's another convergence panel up there which i'm presuming actually swings out so we can look at it from the front um now one thing the only thing i do remember about these sets is on here um there used to be a tantalum capacitor somewhere in the middle um i think it was that one and i think it was c171 but i remember a red one and it was connected across the 25 volt rail and it used to short out the 25 volt rail but i can't remember what this actually caused but that appears to have a blue one in um let's have a look around here that's the degaussing at the top that's the power supply and um sound output which i think that's an mje 340 by memory um that's a va va va-1104 they used to have trouble um in fact i've still got one of these and stuck a brand new one i must go and look it out because um i think there's a problem with these i think they used to vibrate or make a humming noise and and thorne came up with a modification one that was all it potted in uh resin now interestingly enough there's another sticker down there and i can't get the camera in so i'm gonna have to try and pull that out let's just stop the camera and have a look right so that's the sticker out of the set and that's dated eight 1983 which is only about a month later than the date on the one in the back and it's also signed by a different engineer it could be w dunskum um and it says rumblows ordenshaw now this guy i got it from he did originally come from somewhere down manchester so i wonder if this is the next rental and they actually got rid of it because he kept going wrong too often um it certainly looks like it's been repaired um within a month now i've already climatized this set and by acclimatizing it i mean i left it in the back of the car for a few days during the heat wave um so i'm not going to warm it up with a hair dryer and we're just going to reform the cap and uh plug it straight back in right so i've just had to look through all stock from the 1980s and i think i found the part and we're looking for that interestingly enough that's an eht tray and um i think that's from my old shop i think that's probably from a thorn 8 000 8500 but the part we're interested in is this here so let's take it while there's a bit more light right so that's the part i was telling you about this dirty old bag now i've just got it out and if we look down there that's the mains input choke with the surge limiter on um now i seem to remember a technical bulletin where these were buzzing and people complaining and thorn came up with a replacement item now this appears to be the same sort of thing but it's all fully encased in epoxy resin and i think i'm sure i've seen it in ferguson feedback but that was the um that was the recommended uh replacement part to get rid of this buzzing noise and it looks like they've just taken that and filled it with filled it full of epoxy resin so right let's um let's get this set switched on see what happens right now i can't just find the service manual for the 8 800 um but in reality i can't actually remember if there was a service manual for the 8 800 i know it was based on the 8 500 and so maybe you used the um 8 500 service manual and it just had a few different modifications on i honestly can't remember it's such a long time ago but that's the service manual for the 8 000 um 500 and i've got some information here for the 800 series along with lots of technical bulletins and um what's the year on that 1976 1977. had i presume oh yeah that's the um ultrasonic remote control operation for the 8 800 now another interesting thing while we just wait for the capacitors to reform is i'm looking in the back and i'm thinking what's that two bits of card glued on there it's a bit of a mess but then when it turned to the other side of the case [Music] now it all becomes clear um this would have been where a slot meter was fitted um where you put um i don't know was it 50p or 10p i have no idea i can't remember but you put some meter in and you turn a knob and that would give you so many hours of viewing um on your tv so yeah this was almost certainly out on rental uh at one time in its life right so that's the cap reformed um just before we switch it on i've just noticed another interesting thing um the eht tray that i add that i thought was for a thorn 8 000 8 500 and it actually appears to be the correct one for this set so that's another thing i've forgotten about i thought the one i had was for the thorne 8000 but now i'm thinking before 8 000 eht tray was a lot smaller than that um anyway we're all reformed i'll just screw this back in and then um well we'll just power it up and see what happens i think the best thing to do can't do any more damage it's been standing in the cellar for the last 25 years right so just one very last thing of interest before we turn this set on um when i was a kid and i used to go to the tip on my bike and bring stuff back um a long long time ago in the 1970s and i went one day and i found lots and lots of sheets of copper clad circuit board and i brought all this back all this copper clad board it was all brand new but he'd been thrown away for some reason i brought all this back and in them days as a small boy i was always making things out of magazines like practical electronics practical wireless um and i brought all this circuit board back and i've just had a look through my archive and i pulled out some bits what i used to make things with and this is the board in question and uh that's that's a board i made for a power supply there look 1981 um now what's unusual about this board and i've still got pieces of it because it was in big sheets i used to cut up it's all marked bxl the whole lot was mark bxl um now if we turn over to this tv it appears to be the same copper clad that thorne used for making the tvs um let's just move that there let's get the light in there it's upside down of course but can you see the words bxl on the board so if i pull this into the camera we don't block the light you see there so this is without doubt the exact same circuit board i found on the tip um is what they used to make these thorn tvs with so i really don't know where it came from or who dumped it and i've not bxl is not something i've heard of um it's not a manufacturer i've heard of let's see we just turn the camera upside down no that didn't do anything does it yeah so whether it's to come for some some factory that was producing these circuit boards locally i really don't know but anyway let's stop now and let's get this set switched on see what happens right here we go it's plugged in switched onto the socket let's hit the button on the front and nothing's happened no i'm not hearing anything that's well something happened there didn't it and as you can see all smoke pouring out the back right well that didn't go too well did he um obviously needs a bit more uh further investigation this right with a bit more light now i can see what's happened and the cap across the main switch has just exploded yeah so um i'll probably just cut that out and try again right well that's the cap out and as you can see it's totally exploded um it'll only be the anti-mains modulation capacitor so it should work perfectly well without that in for the minute right so it's plugged in now it's switched on i've snipped that cap out and as you can see there's no sign of any display in there um but the crt heaters are lit so they must come from a separate transformer probably down there but i'm gonna have to do some work on this now because uh there's obviously a fault on the power supply right so i've got all the details of the power supply here in the scope day-to-day from 1978. um yeah 8800 modified power supply diagram and that's all i really need to take a look at this set so i'm going to stop the camera and come back to this uh later right well i found while the power supply is not running there's not enough voltage at the anode of the thyristor here now that dial is actually all right and i move down here um and there appears to be a dry joint there on 9.2 a plug in the socket so i'll just see if i can zoom in on the camera and show you that uh in fact when i look at this board these dry joints all over the place it really does need um a lot of work on this board um but the bit that's preventing it from coming on um can you see that dry joint then that plug-in socket um so not just that it needs um a lot of work doing on this board in fact it looks like it's already had a lot of soldering but i can see dry joints everywhere um in fact you can see by how black the board is how hot these run and i remember in this day that resistor was always getting dry jointed there in fact it's um it's been fixed but it's it's wobbling about so yeah it does require an awful lot of work uh this set right so that attended to it's still not running um now i've noticed that we don't have a 25 volt rail here to run the power supply now the problem is uh that 51 ohm resistor there the one that's the hottest on the board that's been uh soldered up it's actually open circuit um now i don't i might have a 51 ohm resistor it takes me ages to look um but i just want to get this some life on the tally and see if it's viable to repair and so taking that into account i'm just going to put 47 ohm in for the minute and uh just see what that does because i'm sure there's going to be lots and lots of other issues with this tv but that's the problem with no 25 volt rail to uh power the um the thyristor drive right okay guys and girls so i got it wrong again uh the resistor's not open circuit i've got 45 volts here um and i've got no voltage there um in fact this resistor is absolutely red-hot um so there must be a short across the um 25 volt rail which this powers now i'm thinking is that the problem i used to have um in the 1980s with this capacitor short circuit i remember it was this one and i remember it was red but i couldn't remember what fault it caused so i'm wondering if this was the problem right so there is actually a dead short across the emitter of vt 702 which is there to ground you can see there um a dead short but it's not actually coming from that capacitor um so we're gonna have to do some unplugging now see where it's actually coming from right so i've one connect i've disconnected to connect to pl4 on the signals panel and the shorts gone away so if we move to the diagram um 25 volt rail there into the signals panel the only thing that could take that rail right down to ground is that capacitor which i've already checked which is okay um but if we move across here there's another decoupling capacitor there c1400 mike now them are the only two caps that would take that rail right down to ground so i'm going to be looking at c140 next right so i've had a good look over this board i can't see c140 but i would imagine it's that one there because it's hundred mike um 16 volt um so now this board actually swings out but i can't remember how we get it out it appears to be tight in um i know he definitely swings out this way but but while i've been trying to figure out how it swings out i have just noticed something so if we come down here you can see that the board isn't actually clipped into the plastic frame properly um i think that board should be on the opposite side in fact if we go around there you can see where the board's not clipped in and i'm wondering now um if we've got short because this board is actually touching on this metal frame that should be clipped right into there so i'm gonna have to figure out see it should look like that and then if we come down it's more and more unclipped um i'm going to try and figure out because i can't remember there must be a catch somewhere to swing that out right so i've got it wrong again that is not the cap i've been looking on the board and also the prime suspect there c171 if we move over to here i thought it was that one there but that's not c171 hc173 so the c171 that there is the suspect i'm going to be taking that out now i'm trying it right so it's not that one so we've still got to continue to search for that one c140 because the short's still there with that removed right so i'll see 140 it's not that easy i've taken them both out the shorts still there but what i hadn't noticed before which i've noticed now the 25 volt rail actually goes straight into a chip there so we could have a chip down so we have to spend some more time do some more investigation but we're making progress i think slowly and with lots of mistakes right so the stupid thing is if i use the million meters to start with i could have found this in a few seconds rather than trying to make assumptions and been really clever reading the circuit diagram but it turns out and it's not actually shown on the diagram uh the part that's faulty so here we've got ic3 uh and pin nine is a 25 volt supply um now i've unplugged that chip because they're on they're in ic socket so it's not that but the shorts coming from here but on my board i've got um a tantalum capacitor connected between pin nine and ground which is not actually shown on this diagram and it is um it's that one there c203 which is dead short so let's just whip it out and then i'll put them all the caps back in right so that's the offending cap out well just clipped on it with some crocodile clips as you can see dead short so i'll remove the cap sure goes away right so that's the problem so let's just get another one in there and then we'll switch on again see what happens right so that's interesting c203 which decouples pin 9 of ic3 that's pin 9 of ic3 uh 1 micro farad 35 volt not actually shown on this diagram and this is according to the front turn it over the correct one for the 8 800 series so um the only thing i can think of is there must be uh different variations of this particular panel right well as i guess you'd expected it's still not come on there's a bit more life than it did before if i press the button and you can actually hear a rumbling noise out of the speaker and i'm not too sure if i can't smell something burning so i think i'm going to wrap this up for the day um because i've got other things to do and we'll come back to this another day right so we're back onto this job now uh while we wait for the post because i can't do anything else to the postman arrives now interestingly enough this cap here um which is it's c171 6.8 mike when i took that out first it was actually okay but since he's had power applied to it it suddenly turned very leaky that's um i've just clipped on some crocodiles there and it's actually measuring about 3k um it's turned into a resistor so i'm wondering now these tantalum capacitors um if we take a quick look the whole board is sprinkled with these i think possibly um if this set turns into be a viable repair it might be a good idea see these red ones blue ones it might be just a good idea um to swap the whole lot because obviously these caps look like they could be very unreliable or um perhaps they don't like standing for a long time and then having power reapplied to them um so let's just see if we can get this set actually to come on first and then if the tube's really good and it might be a good idea to just change the whole lot right so the new caps in i'm going to turn on here so i can stand well back and the first thing you'll notice is the channel indicators lit up on one and i can hear eht rustling that humming noise you can hear in the background that's the isolation transformer um for some reason he doesn't seem to like this set yeah well it's on um the picture's looking a bit uh i don't know if you can see that on the camera we have got snow on the screen but it's looking a little bit dark uh let's just connect this to a sky box let's turn it off and connect it to a sky box while i go and look some leads as you can see it was on right oh okay so we connected to skybox i've tuned it in uh i've tuned it into number two on this touch tuning and um the picture's looking a little bit green so um i think what we need to do now is find the um horizontal hole and just tweak that first and then i might have to test the tube before we go any further it looks very green we've got sound anyway but we did have of course all these are noisy right so that's the time based panel down into the servicing position now the horizontal hole actually turns out um to be this inductor here so we need a non-metallic uh tool and i've got this ck set of trimming tools i'm just going to give that a quick tweak and then we'll come back and definitely it was yeah it's only that we just go well there we go it's actually it's a lot better than what i thought just turn this down yeah well it obviously needs cleaning um but i'm very reluctant just to spray switch cleaner in here because if it's mounted on plastic you usually find that service hole attacks plastic but as you can see plenty of saturation oops what time and it's flaring around here a bit so um it could be that the tube's a little bit warm um but i'm struggling to turn the contrast control down because these are so noisy once each house is renovated the aim is to get it sold as quickly as possible and also we seem to be lacking in a little bit of blue content so i think what i might do is i might just test the tube first and then see where we go from there but all in all it's coming on right so as you can see by the dust it's a long time since i've used this lot [Applause] right so all we've got to do now is just find the correct base right so that's the tube a56 120x all right so here we go a56 120x base seven uh let's see if we can find that and just hope i haven't lost it right well that's a turn up for the box this tube's absolutely perfect in fact it's nearly like brand new um that's the emission on the red gun we're nearly 100 switch to the green gun that's still nearly 100 switch to the blue gun so that's absolutely perfect all the guns are well balanced um so we have the poor pitch we have an electrical fault it's nothing actually wrong with the tube and i can't see this been um rejuvenated in the past because the guy i got it off doesn't have a rejuvenator so right let's um let's switch it back on then have a play with it see what's wrong with the colors tins well as you can see still very very green and we do have massive convergence but we know that the tube is not the problem right that's looking a lot better i'll show you what it was the red green blue drive controls here very noisy so i'm just going to put a little bit of switch cleaner in them first right getting there now and just need to set up the grayscale but look at these massive convergence arrows on the blue um so we'll come to that in a few minutes right so that's looking a whole lot better now on the grey scale right so now let's take a quick look at the convergence errors but i'm not going to spend hours setting all this up because the post just come and i've got some spare parts to do some of the jobs now so that's the uh grayscale and as you can see we've got massive errors here but yeah all in all that's looking really good that's grey scale that's the color bars looking really well so far right now i don't know how well this is going to show up on the camera but the main one that seems to be out is the blue tilt because it's up there and as you move down there it's underneath so um let's have a look at this that's the one there blue tilt the second one after the inductor so that's the convergence panel i think this should lift up um so you can see it from the front but it seems to be a bit stiff that's the one there in fact if you look at the board how hot the board's got um so i might just have to um stop the camera while i adjust that right actually if i'm very careful i might be able to adjust it at the same time so if we look where the blue was there and we need to move that up see that's that's tilting down we need to move that up there and that's not bad that that's about right there wow look at that just needs a couple more tweaks and away we go right so we're still needing a bit more work but i'm going to wrap this up now because i've got other things to do so let's take one final look at the picture fantastic chess we'd love to have you in the studio thank you very much for your time and looking forward to tonight of course you'll be there with gabby and the team and what a squad that is by the way i've noticed all your instagram posts powerful squad like i said earlier you're having a little so look at that guys and girls that's the 1977. so turn it down that's the 1977 thorne 8800 chassis all right many thanks for watching my video and i'll catch you in the next one goodbye with us over on bbc2 though we're going to be bringing you some more balls and we'll be heading to the beach volleyball we'll see you there very soon bye for now [Music] you

Channel: Michael Dranfield

Views: 32,669

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Id: 5cHbzOoDdio

Length: 35min 5sec (2105 seconds)

Published: Sat Aug 06 2022