BACKGROUND INFORMATION
THE EH-1000
After years of use and then storage once the analog Teletext television system was turned off yonks ago, I have finally gotten around to placing this professional, very well built equipment onto the workshop bench ... the "operation" has begun
This equipment was fully functioning but of no possible further use in our digital television (with no teletext broadcasts) era so now I have extracted components and modules "of interest" which can be used to restore another EH-1000 or think of this board as a "component farm" a place where some difficult (or impossible) spare parts may lurk ...
This twin board module "talks" to other modules in the EH-1000 via special "click fit" ribbon connectors (these will be offered separately) and there is no soldering required to fit this board into another EH-1000
One board is "passive", the mechanical keypad, and the second board (upon which the keypad is mounted) contains a few active devices that may be of interest if this module is being considered as a "component farm"
Now it's time to take out the "scalpel" and start the op!
One of the first things to note is that although this is branded Unaohm and manufactured in Italy, the components inside have been substantially sourced from European and English component manufacturers, the likes of Siemens and Philips in particular.
Another aspect that surprised me a little is the extensive use of IC sockets for the integrated circuits on most of the PCB's, a potential source of trouble when it comes to reliability (especially since most of the sockets are double wipe but not machined) but great when the board is being used as a component farm - no fuss de-soldering useful components.
THE DONOR EQUIPMENT
UNAOHM - Teletext Video RF Analyser
Model: EH-1000
Designed & manufactured in Milano, ITALY
Circa Late 1980's (based on advertisements placed in Wireless World at the time and the date stamp on the AC transformer core)
Technology: Analog video broadcast signal analysis - specifically for examining lines of Teletext information "riding along" with the video signal
Luggable (heavy at 15kg) due to the heavy duty Aluminium outer case but more importantly, the inside welded steel frame chassis inside.
Well engineered inside, logically laid out using a number of modules which are well interconnected.
Designed for 220V 50Hz operation (because of this, we used this equipment via an AC variac many years ago)
Green emitting rectangular CRT based front panel display
Interested in the technical nitty gritty? Here is an old copy of the spec sheet
Enough of the yacker, let's "go out into the fields" and see what fruit this "component farm" could provide ...
USER CONTROL (WITH DISPLAY) MODULE
PCB type: double sided
Part #9290/9291
These PCB's are "folded" over one another and kept secure using metal standoffs. Separating the two boards is an easy undertaking, interconnection between the two boards is via a small ribbon cable.
One board has the custom keypad and two IC's associated with the keypad operation, the PHILIPS SAA3004P (Special purpose * See below) and an RCA CD4093 (Quad 2 input NAND gates with Schmitt trigger inputs) - both of these IC's are soldered to the PCB
The orange component sitting between the two chips is a 500Khz ceramic resonator for the SAA3004
The other PCB is all about the control logic and it is populated by a number of interesting components. The passives comprise WIMA block capacitors, a ceramic trimmer cap, metal film resistors and Frako electro's - all of these components are soldered to the board.
The IC's however are in sockets, here is some detail ...
Double wipe sockets: NATIONAL LM358, MOTOROLA MC14024 & MOTOROLA MCM2802 (32x32 bit serial electrically erasable PROM) - full technical data on this device can be found quite readily online.
Machine sockets: PHILIPS SAB3035 (Computer IF for digital tuning & control) & PHILIPS MAB 8461P (8 Bit Microcontroller 6K bytes ROM 128 bytes RAM & 8 bit LED driver) - again, I found it was not difficult to source technical data online about these two special devices.
Please keep in mind that the EH-1000 (and thus this board) has been and was FULLY OPERATIONAL - you can be confident these devices will perform as designed.
This module was FULLY FUNCTIONAL prior to removal from the equipment, meaning that if were looking to "bring back to life" another EH-1000, this complete module 9290/9291 could come in very useful
PCB DIMENSIONS:
125mm x 70mm x 30mm height
WEIGHT: 130g
This 9290/9291 module has now been "laid to rest" within an ESD bag, bubble-wrap and is lying on a stiff cardboard backing, everything then within a sealed clear plastic packaging, ready for a trip to another resurrect another EH-1000 or become an "organ donor" for other equipment.
