Horizontal (line) Hold/Vertical Hold on old (pre mid seventies) TV sets

Mike 1972

Prior to the mid seventies (and later in the case of some cheap portables) there were usually a bewildering array of controls on the back of a typical TV set:
Vertical Hold (sometimes called field or frame hold)
Line Hold 405 (seperate controls on dual standard sets)
Line Hold 625 (Somtimes called Horizontal hold)
Height, Width and Linearity (not on all sets)
White Spot Limiter and Noise Limiter (more upmarket versions of 405 or dual standard sets)
Some also had the brightness and/or contrast controls on the rear but it was more usual to have them on the front.

Most of these seemed to be pretty much "set and forget" with the exception of Vertical (and to a lesser extent horizontal) hold which at least once during the course of an evenings viewing tended to go awry with the picture bending at the top or breaking up completly (horizontal hold) or black bar moving up/down the picture and the bottom getting mixed up with the top. (vertical hold) Necessitating someone (usually an adult since the back of the TV was inaccesable to us kids owing to physical but more usually parental constraints) getting up reaching/feeling their way around the back of the set (not easy as TV sets were bulky back then -even when the screens were small by modern standards) and fiddling with the appropriate control.

Thing I could never figure out is why did they put a control which required adjustment on such a regular basis on the back of the set ?

Tom Slick

Mike 1972 wrote: »

. . . Necessitating someone (usually an adult since the back of the TV was inaccesable to us kids owing to physical but more usually parental constraints) . . .Thing I could never figure out is why did they put a control which required adjustment on such a regular basis on the back of the set ?

Might have answered your own question there.

Mike 1972

Tom Slick wrote: »

Might have answered your own question there.

Perhaps but if thats what they were thinking then why didnt they all stick the brightness and contrast around the back as well ?

On the plus side I suppose it helped cut down on lazy parenting and the use of TV as an electronic babysitter

On the other hand even smaler/less dexterous/partially sighted adults struggled to find the controls at times.

Tom Slick

Mike 1972 wrote: »

Perhaps but if thats what they were thinking then why didnt they all stick the brightness and contrast around the back as well ?

I'd imagine the real reason was simply the siting of the internal components and avoidance of awkward control linkages/wiring etc.

Sam Russell

Most of those old TVs were fully valve sets and had poor design, with low gain. Also most signals were weak because of poor aerials and cables, and the sync pulses were easily lost. Put it down to poor design.

With the introduction of integrated circuits and general standardisation, the circuits that control those parts of the TV were capable of locking the weakest of signals. The dual standard sets were a marvel, not that they were so good, but that they were so bad. Full of multi-pole switches that were cheaply made and switched tuned circuits directly, which is not a good practice. I think they were called turret-tuners, or something like that. RTE should never have gone down the 405 route, but they did. Too many 405 sets in circulation and because they broadcast in 405, encourage more onto the market. No STB in those days. TVs were very expensive then.

At least with Saorview, they are going HD from the start.

Mike 1972

RTE had little choice in the matter.

The installed base of 625 capable sets in 1961 was close to zero

Politically it would have been difficult to collect a licence fee from 405 line only set owners with no prospect of them ever being able to recieve the new service without buying another (expensive in those days) TV.

A hybrid 405/625 service while making it clear that this was just a temporary arrangment was the only real solution.

Sam Russell wrote: »

At least with Saorview, they are going HD from the start.

But this opens up the whole "they ought to use DVB-T2" debate.

Tom Slick wrote: »

I'd imagine the real reason was simply the siting of the internal components and avoidance of awkward control linkages/wiring etc.

I have an old book (purchaced at a library sale) which goes into great depth about the internal working of 1960's era "dual standard" sets. They were horrifically complicated beasts (no wonder they were constantly breaking down) operating the 405/625 switch seemed to link to (at least) twenty other internal switches in various circuits inside the set. Working on such sets must have been an absolute nightmare. French 819/625 sets were probably even worse given their 819 channels used overlapping channels with sound below vision on some channels and above it on others. Maybe this is why they made the (otherwise rather strange) decision to stick with positive video modulation and AM sound on 625 in order to keep their dual standard set designers/service engineers from losing their sanity ?

Sam Russell

Mike 1972 wrote: »

I have an old book (purchaced at a library sale) which goes into great depth about the internal working of 1960's era "dual standard" sets. They were horrifically complicated beasts (no wonder they were constantly breaking down) operating the 405/625 switch seemed to link to (at least) twenty other internal switches in various circuits inside the set. Working on such sets must have been an absolute nightmare.

The technique was to give them a good whack on the top. If that did not fix things, a good whack on the side. The problem was always a poor contact on one of the many switches. Lin-ouput-transformers were a particularly weak part of the design as it was dual standard as well and was a highly stressed part. Horrific. But they took a long time to die, as the market here for 625 line sets was small and had to wait until the UK went 625 full service. One technique was to prevent the dual switch from being activated, generally by using a large screw. More horrific were the dual standard colour sets. Tuning was done using a tiny screw, for each channel. Fortunately there was only one channel for most people.

Tom Slick

Thankfully, these days with digital technology it's a lot easier (& cheaper) to turn out dual or triple standard sets (DVB-T MPEG2 & MPEG4, DVBT2, DVB-S/S2). The actual display can work with any of these and their various resolutions.

I can be fairly sure today that if I buy a DVBT2 Freeview HD TV, it will receive Freeview SD, Saorview & by end 2012 (hopefully) Freeview HD. I also have the HD sat. option in the meantime.

Sam Russell

Tom Slick wrote: »

Thankfully, these days with digital technology it's a lot easier (& cheaper) to turn out dual or triple standard sets (DVB-T MPEG2 & MPEG4, DVBT2, DVB-S/S2). The actual display can work with any of these and their various resolutions.

I can be fairly sure today that if I buy a DVBT2 Freeview HD TV, it will receive Freeview SD, Saorview & by end 2012 (hopefully) Freeview HD. I also have the HD sat. option in the meantime.

The first standards conversion kit (for 525/60 to 625/50) filled a room, now every little 2 bit TV can do it on a little chip without much of a blink. Progess, eh?

The digital technology has certainly helped, but I fear it is being used to increase quantity rather than quality. Bit rates are screwed down to allow more crap channels at the expense of picture quality. The engineers and their friends, the beancounters are in control. But hope is there and HD is coming.

watty

The 1st setbox was to add ITV Band III 405 line to Band I BBC only TVs
In 1950s

Two versions.

Belgians had Quadruple Standard TV sets

Sam Russell

watty wrote: »

The 1st setbox was to add ITV Band III 405 line to Band I BBC only TVs
In 1950s

Two versions.

Belgians had Quadruple Standard TV sets

I thought the Belgians weren't famous for anything.:D

Mike 1972

watty wrote: »

The 1st setbox was to add ITV Band III 405 line to Band I BBC only TVs In 1950s

Around the same time they had UHF convertors in the USA for VHF only TV's

By all accounts they were horrible things.

Sam Russell wrote: »

I thought the Belgians weren't famous for anything.:D

Chips, Choclate and hosting other peoples wars ?

watty

Very small cabbages due to the narrow streets in Brussels?

They aren't even sure if they want to be a Country, or if part should go to France and part to Netherlands.

Antenna

A few days ago I came across a user manual for a PYE B/W TV, it looks like its from the 1970s.
See attached. Reading the manual it had both H and V Hold controls at the back. Contrast control was also at the back.
Also notable is the separate VHF and UHF inputs.
(were these TVs assembled in Dublin (Dundrum), as the manual gives that address?)

Here's pages 1 to 5

Antenna

heres the 3 remaining pages (6,7,8) of this Pye manual

Sam Russell

The reason controls were on the back is because the pots were on the (main) circuit board, and were actually in circuit, so they had to be there, near their active components. There were not many components in a telly then, as few as possible, and the whole design was very crude by modern standards, and even perhaps by the standards of the day. TVs were very expensive relative to wages at the time, and had to be made cheaply so they could be afforded.

rlogue

Well given the modified Test Card C on show I would have put the manual as late sixties as Test Card F was used on BBC 2 from December 1967 onwards.

Sam Russell

I would have thought it was later as that is a single standard set, with transistors rather than valves.
Maybe 1973 or so.

watty

"Transistorised" didn't mean all transistor then.

rlogue wrote: »

Well given the modified Test Card C on show I would have put the manual as late sixties as Test Card F was used on BBC 2 from December 1967 onwards.

Correct. It's maybe the very first single standard. The 368 or something was concurrently available Dual Standard cousin.

B&W used transistor LOPT before Colour. Also it might have used a valve for line scan and LOPT and still be called transistorised.

BBC2 started in 1964 and RTE 625 line effectively in 1962?

This could even be 1965. However it has Brown and Blue for mains lead. I don't remember when that started (wiki has dates for fixed supply wiring which is much much later)

[Edit been suggested to me that these models used valve field and line timebase, maybe even audio. Transistor tuner and IF. ]

rlogue

BBC 2 didn't start from Divis until March 1967 so a single standard set would not have been viable until then but also bear in mind that BBC 1 and UTV did not go 625 UHF from Divis until 1970.

watty

Yes, but the same Pye chassis was used in England as well as Ireland also it is a simplified version of a concurrently sold dual standard.

Anyhow I'm told that model came in 1969 and that the Brown & blue wiring mentioned also only came in UK in 1969.

So rlogue correct, very late 1960s, with perhaps some documentation copied from earlier model, may not even have been sold in Ireland till early 1970.



Valves used (possible function):
PL504 (LOPT/Line drive) ,PY801 (boost Diode) ,DY802 (EHT?), PCF802 (video drive?), PCL805 (Field or Audio) ,PCL86 (Audio or Field)

The set used transistors and ICs


Shown with chassis hinged down

Long tube is resistor in series with all the valve heaters (also in series).
Chassis is "live" (neutral really) as only the on/off and a single rectifier is between the chassis and HT and the mains.

You can't see controls because chassis is hinged down. If you look carefully you can see SEVEN valves
(if you include V1 = CRT!)
Just the tip of one behind LOPT cage, and the EHT valve with rubber cap.