British 405-Line Television

The DOMINO 625 to 405-Line Standards Converter

Television Set Service data and Other Stuff! (Scanned from Newnes books and Original Manuals)
Documents are presented in Adobe PDF format and using Acrobat Reader 7.0 is suggested.

You can get the Free Acrobat Reader from here.. Adobe

Alternatively there is a PDF reader called "Foxit Reader" You can find it here.. Foxit Reader,

The Channel details and much more are in this document... BBC 405_Sites (100kB pdf) scans of
BBC nformation Sheets showing BBC Television Regions and Television Transmitting Stations
relating to VHF 405-Line television coverage.

Vintage TV: The Bush Model TV22  An article by Malcolm Burrell, from 'Television' 1979
(Reproduced with the authors permission)

Ultra V71 and W72 Series  Models V710/711 and W720/721 etc..

The popular Sony Dual Standard portable
Sony TV9-90UB Newnes  Complete scan from 1970-71 Newnes Book.

Sony TV9-90UB Diagram   Scan from Sony Manual, Diagram only. (Full manual to follow later)

Bush TV92 and TV93   405-Line Bush from 1960 (ish!).

Masteradio T851_T852   Masteradio 12 inch CRT TV from 1953.

GEC_BT1091B   GEC 9 inch CRT TV from 1949. (This set is very heavy)

All the manuals here will print out on A4 to the correct size if you set "Fit to Printer Margins"

A TV9-90UB running on the output (405-Line VHF Ch1) of a DOMINO converter,
at DOMINO's first showing at the NVCF May 2003, this set runs fairly well, no kinks or cogging,
just an occasional fieled roll on scene changes!, but another example is not so well behaved.

The other picture shows the MkII converter, 405 line TCC and the Sony TV9_90 "monitor"

I investigated this, (not very easy on this set as there are just to much works in there!)
The video signal at the detector (D301) was showing "sync crushing", this did not vary with signal
level, feeding external video (405 line 1V pp) direct into C504 gave good results, showing the
sync seperator was ok, as the set worked very well on 625-line I did not investigate any further.

I have another of these sets that has been "Modified" to become a video monitor, (well it had to
become a monitor as the tuner and IF stages were missing!) it works well with 1V of video fed into
C504, (you have to live with the lack of a black level though) this was used during my first converter
experiments. It now has a permenent Test Card C on the screen, even when it's off!.

Telequipment Advertisment   A Test Card for the TV factory! from 1961.

The Test Card was produced by a special CRT called a 'Monoscope'
The required image can be seen on the plate at the front of the CRT,
when scanned, the resulting image signal was picked up from the connector
in the 'hole' at the front, after amplification, blanking and sync pulses were,
added to make a composite video signal.

This example was sold on eBay, it produces a Telequipment Test Card C.
Telequipment made Oscilloscopes up until the late 1980's

BRIMISTORS (STC)  1958 booklet about Brimistors types CZ1 to CZ12
Thermistor devices used in TV sets and Radios! (noisy things with no pictures!)

Telequipment Osilloscope D1010 & D1011  Manual scanned from a Photocopy.

Bush TV22 Focus Lever Template  Make a replacment focus lever from this template. 

Informative article describing how the IBA developed a digital 625 to 405 line standards
converter, scanned from IBA TECHNICAL REVIEW no.3 dated June 1973.

A Standards Converter Using Digital Techniques  2.4MB pdf

Some of the devices used were state of the art at the time, today the interpolator with its delay lines,
multipliers and adders could be fitted into a large FPLD with some room to spare and would consume
a lot less power! (4A per multiplier module, see page 25)

The stores used were shift register devices, they did not have any read or write control, so three
line stores were needed to make sure a store was ready to be written to while one was being read.
Today’s large FIFO’s have independent input and output control making the time redistribution
a lot easier to do.
It should be noted that although the IBA developed this digital converter it was not used to replace
the analogue converters (made by PYE) that were in use, ITV carried on with these until the
closedown of the 405 line service.

Update April 2008
I found a couple of patents describing the IBA standards converter(above), By J L Baldwin, assigned to the IBA, Contains a description of the operation and some block diagrams.
Converter_1973.pdf and Converter_1977.pdf

Article describing, BBC Experimental Converter. Scanned from Wireless World May 1971.

Digital TV Line Standards Converters  Painting by numbers. 86KB pdf

The interpolator in DOMINO works in a similar way to the linear interpolator in the BBC
experimental converter.

Televison Standards Conversion  A Direct Electonic Method. 440KB pdf

Here are a few pictures of the first version that made it onto a pcb, the preceding work was done
on a prototype "bread board", the ADC, DA converters and the line delay FIFO's came from a scrap
Videocrypt decoder board (Used with analogue SKY TV).
This design does not have any line interpolation, it has the input clock locked by a PLL and the read
clock 'hard' locked by the output controller.

Shown here is the MKI on top of a matching UHF tuner (next to a DOMINO!)

No modulator yet, that will have to wait.. only video in and out for now, work on a suitable
Modulator came later, eventually a design using MC1496's with crystal oscillators was used.
The pcb in the MKI is a 100x160mm Eurocard and was made by me.

Here are some clickable pictures of the schematics for the MKI

The pictures are quite large and not as clear as they could be, but here is a .pdf of
the schematics which is better when printed. MKI Converter

There are a few things in that design that are not very good, the input and output filters for a start!
and the preset capacitors used for the oscillators are horrid, but it was a proving ground.
The converter used PIC16F84's and had several adjustments, DOMINO has just one!.

Following the MK1 there was a version with an interpolator, this needed another line delay FIFO
and used a large EPROM as a lookup table for the interpolated values, at one point there were three
PIC micro's in this version of the converter!.
The results obtained from this showed that a design capable of producing a good 405-line picture
would be practical and could be built using mostly standard legged components.

DOMINO standards converter and Modulator as a pdf, A2 size drawings, Domino Diagram
To print out on A4, set "Fit to Printer Margins" (as Landscape) in the print options.

Modulator and power diagrams. (There are two versions of the modulator circuit)
Modulator V1  and the later version...   Modulator V2   both versions were made as Ch1/Ch4

Pictures of PCB's  Domino Converter Board   and the later Modulator Board...  Modulator V2
The V1 modulator board will be added later...

Design © 2006 Malcolm Everiss.