Ferguson Colourstar 3713 BRC 8500 Chassis restoration

[yampy187]

Hi All

I have up on the bench a pretty tatty example of a BRC 8500. Obtained from a popular auction site a few weeks back. It looks to have been a quite high hours set with a fair few replacement components.

Initial checks revealed one of the big can electrolytics (700uf 250v) to have spewed its guts out and significantly dropped in value. after tacking in a temporary replacement and checking fuses i applied power. the set sprang to life with sound and an out of focus raster of sorts.

Only one channel selector works due to the usual Thorn tuner plastic rot. I managed to tune in my pattern generator and obtained a badly focused, mis-converged crosshatch. Then the frame collapsed.

I have currently stripped the set right down to clean everything carefully and thoroughly and re glue the top of the cabinet which practically fell apart. It was all in a pretty nasty fag stained mess.


This is as far as i have got for now. More to follow  

Jan

[Geordie McBoyne]

Poor focusing: A common fault with the 8500 and 8800 series was the resistor in the EHT rectifier tray going high value. Some timebase panels employ a BF256 FET as a source follower which serves as a buffer between the field timebase sawtooth forming capacitor and driver of the output stage.
In later timebase boards the FET was replaced by a BC147 transistor.
I notice that your set has the early production signals board. In 1975 a replacement board was introduced, the type PC651.
All in all these were good reliable sets, I had loads of them out on rental. Marketed as Ferguson, Marconi and Alba. The latter was the most popular with customers.

Geordie McBoyne.

[Geoffrey]

Hi,

Your pictures take me back in time, I sold and rented out many of these sets.  Repairs in the home were commonplace then and I remember the care needed to avoid burning my fingers when removing the power board.  Finding which of the red tantalum capacitors on the IF / Video board had gone short circuit was always interesting!

Best wishes, Geoffrey.