1978 Roberts RCT-262/T
Model: Roberts RCT 262/T
Original List Price : £000.00 ( to be ascertained)
Integrated Circuits: Yes
CRT: A56 510X
A fairly rare set this? Well can’t say i’ve come across one before. Aimed at the luxury end of the market during the late 70’s, this Roberts RCT-262 would have been expensive back then. I believe the previous model (261), retailed just shy of £500 which would have been a sizeable sum, probably in today’s money £2,600
The 262 was the next model on from the Roberts RCT 261 (Philips G9 chassis), employing the newer Philips G11 chassis. The G11 series all solid-state colour television chassis was designed for both colour and black & White reception on 625 Lines UHF. The 110 deflection 20AX CRT is self converging and has quick vision guns to provide a viewable picture within roughly 5 seconds of switch on.
Most of the circuitry is accommodated on five main PCB’s ( Line-scan, Power Supply, Timebase, Decoder and I.F) which are vertically mounted on two sub-chassis.
These sub-chassis are pivot mounted and can be hinged open from the main chassis frame, giving easy access to both sides of the panels. To open out the a sub chassis door you first need to release a locking catch at the top. You then slightly lift the sub frame up and pivot to swing out, there are two positions, half open and fully open. Any of the panels can be unclipped and removed to the bench for further inspection.
In addition to these five main panels there are three smaller printed panels (mains input, dynamic correction and CRT base). These smaller panels are equally easy to remove and may be withdrawn to the extent of their connection leads or unclipped for full removal to bench.
On the front two control panels are pushed and pop out, the top one being the tuner, the bottom one being the picture settings. At the rear there are two DIN sockets and a loudspeaker on/off button. The whole set combined in Teak cabinet with a single tambour door.
The CRT used in the set is a 20AX in-line system specifically a Mullard A66-510AX. EHT 25kV
First initial inspection revealed the EW correction coil on the line-scan panel, had lost its top cap and sprung away. The top was found rolling about in the bottom of the cabinet. Luckily I had a spare line-scan panel so a transplant was performed.
Replaced the PYE red smoothing as there are notorious for causing and HT spike sending EHT up through the roof. In the worst case blowing a hole in the CRT neck. This is due to the rivets on the electrolytics terminals being of poor construction, the later blue type should be fitted.
Full mains was applied and first light achieved. The resultant test card was superb with excellent colour and geometry. I was initially fooled by the lack of sound but this was quickly traced to the loudspeaker button at the rear.
This is used to switch the main speakers out when connected to an external audio source.However after about 15-20mins the picture started to turn a blue-ish cyan colour red seemed to have gone and fly-back lines became visible. The set was switched off for around 10 mins then back on again the fault had cleared. This is likely a heat fault and is where I’m at now seeking the likely candidate, freezer can at the ready.
However the fault seems to have vanished after turning off for a while then turning back on. Wondering if its heat related and a transistor is protesting.
I will investigate the decoder board which has BC148 T15 delay line driver, BC148 T5 Pulse Inhibit, The three colour output transistors T105 (B) T93 (G) & T83 (R) which are BF458’s. The two IC’s on the decoder are IC520 TBA540Q reference combination and IC530 TCA800Q Colour demodulator.
The set also developed an intermittent frame collapse, this was suspected to be know issues with the Frame IC socket. A new one was installed and the fault was still intermittent. There must be a dry joint somewhere so further investigations are required.
Hooked up an early 1970’s set top Teletext decoder. My analogue network has an Imogen that hosts 15 pages of text.
I think this set is an early G11, all the evidence points towards it being so. The original Red Pye Philips PSU cap ( 470uF) , the Frame IC socket, a known issue and the set has the ultrasonic remote board installed. The set came without the remote, however a spooky happening, a box of bits arrived from another source and it contained would you believe a Philips ultrasonic remote control handset. Next job is to try and get that working.