Which was the worst TV set / chassis you had to repair

[TonyDuell]

Not a TV, but a colour monitor : The DEC VR241. It seems to be a Hitachi design. The switch-mode PSU is driven from a winding on the line output transformer. There's a separate startup oscillator to get things going, but that is turned off when a capacitor on the PSU board charges up. Meaning that for the PSU to run, the line output stage must be running. And of course for the line output stage to run the PSU must be giving the right voltage. At least the drive signal is transformer-isolated on the PSU PCB so there's no live mains on the deflection board.

Oh, and there's a thick film module in the middle of the deflection PCB, the deflection control IC is on that. As is the entire vertical output stage.

No, I did not like repairing that....

[Nuvistor]

I was only in the trade for the 1960’s and 70’s, 20 years I suppose.
I can’t think of any of the sets I looked after were difficult to fix, perhaps that was due to the relatively small range I looked after.
There were some poor execution of perhaps reasonable designs. The Pye 40 chassis BW set with the IF strip shoe horned on the back of the tuner, it’s push buttons flying off but not difficult to repair.
We dealt with Pye/Ekco, RBM, ITT, Toshiba, Hitachi, cant think of others, all had there failings but straight forward, some a bit more challenging to get access to the components.

Certainly didn’t have the horror stories to deal with like some of the horror sets noted in the thread. Seems some of the worst offenders came after I left the trade.

[1955APREN]

Not the tv itself but. The TUNER UNIT used in the McMICHAEL mtv {possible mod no 284} . It had 4 push buttons 2 for BBC 1and 2 for Itv .When the button were engaged a slider with spring connects on moved across a printed circuit board to select the channels. The small firm that I worked had some of these on rental . the rest of the set was nice to work on just the odd frame stage faults.
McMICHAEL introduced a different type of tuner it had round buttons as was a bit like a bush one.When I approached boss with a view to obtaining 10 of these mod kits He went through the roof and would only order one. I still had try and repair the ones with this nightmare tuners in.

AS regards the Matsui 209r/t these set should Never have seen the light off day
How they got passed inspection no one knows
Derrick

[Heatercathodeshort]

Yes totally over the top. I used to look after just two. They were both HMV 26" consoles, I think the only version that was released and suffered from endless problems. No wonder the export order was cancelled. They probably assessed a few then gave the thumbs down.
Thick film units were completely pointless and just added to the unreliability to all that used them. J.

[MickMcmichael]

As people have said, each era has its duds. I agree with all the comments re Sharp CS and double deckers etc. All terrible things!

For me, the worst thing I remember trying to fix were some of the later model CRT sets. The worst being the Philips EM range of chassis.

They had two switch mode power supplies: one for HT and one for 5v standby. They went BANG big time. Philips released two different part kits for a fix after said bang had rattled the rafters. About 20-30 components in all including surface mounts if you re-built both supplies at the same time.

You just knew it wasn't going to work. It didn't and it often went bang again!

They also had a large digital processing board in them that often gave a picture that looked like it had been painted on the screen. Massive chips and no boards available from Philips even under warranty.

Dreadful damn things.

[Maarten]

The worst repair kits could also be those for the MSM and NSM video power supplies. They inevitably blew up again after fitting as the one diode that usually shorted wasn't included.

[slidertogrid]

Originally Posted by Richard_FM

I remember the EMO sets from a thread on hard to find / extinct sets.

Didn't they have a SECAM decoder converted to PAL? Also the transformers weren't really designed to run on 240v from what I remember.

Where any other difficult to work on sets imported during the colour boom?

I think someone mentioned the original plan with the likes of EMO were to just rent them out temporally until the supply of British made colour sets caught up with the demand.

This took longer than expected so, many ended up being rented out until things started to go wrong.

We Had them all at the place I first worked when I went into the trade. The 'colour boon' sets were 6 or 7 years old by then and some were packing up fairly regularly .. We had Emo, Finlux Peacock, Teleton hybrid, Grundig 711 with the line driver transformer that burned up! All the models of hybrid PYE from D/S to CT205 ( I quite liked them as easy to fix) Bush A823 . We also had a few Tyne sets which were OK but looked a little "home made" ISTR.
The worst sets were I think, made by Berry, a sort of CVC5 copy with a 25KV overwind on the LOPT instead of a tripler. The LOPTS failed and failed.

The main reason for keeping these sets going was that they were decontrolled and could be rented with a small deposit where as if you rented a new set you had to pay a large advanced rental.

By about 1979/80 they were disposing of all of these sets, the service manager decided the call rate was too high and we were having to stock all sorts of obscure parts. Often a set was returned to workshop because the field engineer didn't have the parts on the car.

Mechanical tuner PYE hybrids started to be disposed of the following year as MCES stopped repairing the tuners . Most were still on the original tube which was getting past it's best it was decided it wasn't worth fitting a regun as the sets days were numbered.

The firm had obtained other firms rental accounts which brought with it a fair few Thorn sets and 823s these were disposed of as soon as they came in .
I bought many and supplied friends and family. A practice that eventually got me into trouble for doing private jobs...
Happy days!

[malvision]

Decca 100 so many problems,still have the scars of head scratching 40yrs later

[Welsh Anorak]

I'm surprised no-one's mentioned the Philips G9. A reasonable development of the G8, I suppose, but let down by those two big capacitors.
And where's the Pye CT200? Not too difficult to fix - usually - but that picture!
I think the German ITT was the FT100 with the 25kV overwind on the LOPT. Like the G9, you thought you were getting a CVC8 or G8 until too late.
Not vintage, but dare I mention the 55" Samsung curve with the screw-free back? Always a gamble that the screen will survive its removal...

[Richard_FM]

I've heard the Philips G11s could be tricky to work with.

[Welsh Anorak]

Not really if they were your day to day repairs in the Eighties. Many faults, of course, but predictable in the main.
The big problem was the early smoothing capacitor that arced on the tags and wrecked the line transistor, the frame IC and could pop the tube. If you had a short BU208 and an early capacitor you'd check the CRT hadn't got a hole in the neck. The pale red ones were 'change on sight', but some early blue and green ones were suspect too. If in doubt, you always replaced with a later welded part.

[McMurdo]

......fabled Amstrad CTV2200. Not a bad looking set...

That's surely a philips K35 mounted upside down?

Anything from the dying days of widescreen 'flat' CRTs for me. Heavy to mandhandle, difficult to get on the bench, precarious CRTs swaying in the breeze under their own weight when the back was off, and you never knew if you were looking at a dry joint or a corrupt eerom.
And dont get me started on the philips painter sets. Weird faults that normally 'just can't happen'.

[Red to black]

Apart from the usual suspects already mentioned, although I did repair quite a few Sharp CS sets, the Amstrad not so much as they were a good source of A56 540X tubes .
The Charlie deck and Pana G decks were not too bad to do most of the time, I could re-build most of those in about 20 mins, just the odd one could fight with you and end up taking all day!
The later Funai decks with the soldered ribbon cables and all of the motor driver chips contained within the capstan motor were just crap no other comment really needed here.
There was an LG set (CRT) that had various incarnations of field output mod kits, most of which had various larger heatsinks to be bolted on the original, I don't think the problem ever really got solved satisfactorily, Likewise one of the Samsung 20" models that used an SMR chopper chip, again this mod kit went through various incarnations and even then still failed after about a year or so.

The Thomson sets: I liked the ICC5 you just had to know how it worked although the IMC versions were far more tricky at times, the IKC2 could be tricky in the PSU and Lopt department, the ICC7/8 were easier to repair likewise the ICC17, SM jungle chip failure aside on the ICC17 that often failed on its EW output pin when the lopt died.
The ICC9 and IDC2 sets were the least reliable and could be a PITA, more so the IDC2 because this really needed extension leads to work on the two digi modules (ITT Digi chipset here) while powered, they were both plagued by SM transistor failures all over the set BC849/BC859, I wonder if Thomson had either a dodgy batch, or dubious production methods ?

The FV30/31 and 32 could be a bit of a nightmare on earlier models but after Ferguson/Thomson modded them later versions were a lot more reliable in the PSU department. The ICC20/21 were very complex sets and could be difficult to fault find on however they were fairly reliable overall and only had a few stock faults which were fairly easy to fix once you knew their weaknesses.
I didn't like the two Akura sets with the ITT digi panel much either as it was just unreliable junk.
Then there was the various Onwa chassis (what were JVC smoking?) that even after all the mods to the psu were done still bounced back after a year down the line for similar problems, obviously just another crap design.
Most of the Vestal CRT stuff whilst being cheap and cheerful and not the most reliable were cheap and relatively easy to repair they were not bad to work on either.

The Sony AE 5/6 and 7 had a very strange line output stage which consisted of two line output transistors, one was driven as normal the other was phase advanced and retarded wrt the first and this was dynamically updated on a line by line basis to do the geometry correction, it meant the analogue signals (parabola etc.) were only available at the jungle chip output from then on and throughout the line output they were PWM so again you really needed to know how it worked to stand a chance of fixing it, coupled with elaborate and complex protection circuitry these could be very difficult to repair.

The Salora M chassis deserves a special mention too, we had some weird and wonderful faults on these, the Ipsalo circuit was quite complex and using Digital (ITT again!) could make life 'interesting'.

I think that is about it for now unless I think of any others

[AJSmith625]

With reference to Glyn's post #49, I had a G9 in the early 80s. Another freebie given to me by a mate also in the trade who I had done some work for. As I was going to keep the set myself the first thing I did was to replace the 2 troublesome electrolytics on the line OP panel, but as an experiment I decided to strap the new ones outboard on the vertical chassis strip at the back of the panel in an attempt to keep them cool and wire them into circuit keeping the wiring as short as possible. I also fitted a 0.1mfd ceramic cap across each electrolytic as I remember one of our lecturers at tech saying this was good practice when an electrolytic was being used in a high frequency application. I never had to change these again and had a good few years use from this set.

Alan.

[Hybrid tellies]

I was not a big fan of the Philips 210/300 chassis. Awkward to work on and they played up in damp houses. As most of the local stone used for local house building was rather porous there are many houses that suffered from the damp in this area.

My next pet hate was RBM's A774. Many of these suffered strange intermittent faults and the pictures were not terribly good. The A774 was a big disappointment after the excellent A640 chassis.

Of the colour sets, Pye hybrids were ok as long as they were not fitted into a poorly ventilated boxy Dynatron cabinet. Their all transistor large screen chassis looked and were a mess with those awkward vertical panels, thick film resistors and IF dry joints. They just did not work well producing poor pictures and were a nightmare to repair.

I was not a big fan of the 26" Grundig 5011's with their thyristor line output stages and those 110 degree tubes did not last long.

A few years later the Fidelity ZX3000 chassis was unleashed, with poor reliability and not so good pictures. Things got even worse when they lashed this terrible chassis into the AVS1600 and AVS2000. Both total wrecks from new.

I have repaired a few Amstrad 2200's in my time. When they worked they could give reasonable pictures but when they blew up they did it in style and it was a case of following the trail of destruction.

[Red to black]

The Fidelity ZX3000 wasn't too bad, they had predictable faults and were relatively easy to fix, I preferred them to the earlier ZX2000 chassis.
There were quite a few interim updates to the ZX3000 with different decoder chips and remote control chips ostensibly called the ZX4XXX chassis, and this was far better than the later cut down and half-assed ITT Digi (again!) ZX5000 abomination.
While the digi section albeit cut down (no digi sound processing) was reliable enough The PSU on the ZX5000 itself wasn't.

Edit: if I recall the development of the ZX5000 chassis was held back due to numerous problems with this chassis, also Fidelity changed hands around this time and had serious finance problems hence the updated ZX3000 versions aka ZX4XXX.

[Welsh Anorak]

The problem with the ZX3000 was the mods you had to do when changing the jungle IC. Not a big deal, except when fitted to an AVS as the wires were too short. Also there was no labelling on eiter side of the board making the job twice as long.
Hmm - the 5000. Bang!

[Skywave]

Originally Posted by Hybrid tellies

I was not a big fan of the Philips 210/300 chassis. Awkward to work on and they played up in damp houses.

My distant memory of those sets was that they seemed to have a voracious appetite for LOPTxs.

Al.

[Michael Maurice]

The Later LO6.1's and EM series which had the line output and E/W circuits on the live side of the mains, isolated by pulse transformers and optocouplers.

[Red to black]

Originally Posted by Michael Maurice

The Later LO6.1's and EM series which had the line output and E/W circuits on the live side of the mains, isolated by pulse transformers and optocouplers.

I think one or more of the Decca/Tatung sets (F and the G series) followed this Topology as did the Pana Z8, things seemed to be changing just at the designers whims at this point in time, especially when there was already well designed reliable sets that probably would have benefitted from more advanced and economically prudent chipset changes than this rather radical design departure.