BRC 1500 stock faults - UK Vintage Radio Repair and Restoration Discussion Forum

Hybrid tellies · 16th Feb 2004, 10:51 pm

For the less enlightened stock faults was a trade name for common or frequently occuring faults mostly on televisions.

humorist2751 · 18th Feb 2004, 12:23 am

Poor sync on BRC/Thorn 1500 series chassis was usually caused by failure of R44 (sync. separator screen feed resistor); the cure was to replace this with a component of at least 1 watt rating.

It's half Lombard Street to a china orange (as my Dad used to say) that any 1500 still extant will have had this done long ago! I guess this could well be true for many stock faults - but it's still good to know about them.

Somebody has already mentioned the no sync fault so here are a few more.
Weak video with lots of streaking: R40, R41 video output stage load resisters gone high or o/c. Both can be changed out using 1 x 3.3k and 1x 3.9k 1w resisters. Same symptoms can also be caused by electrolytic cap C37 (64uf) which feed video to base of video output transistor.
For poor frame linearity and frame jitter change out R101 & R102 both 18k 1w resisters. These are fitted across the primary winding of frame output transformer.
Frame cramp on bottom of picture with poor frame hold. C89 (1uf) dried out. This capacitor smooths the boost line feed to the frame oscillator.

16th Feb 2004, 10:51 pm	#1
Hybrid tellies Nonode Join Date: Jan 2004 Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area. Posts: 2,965	BRC 1500 stock faults For the less enlightened stock faults was a trade name for common or frequently occuring faults mostly on televisions. __________________ Simon BVWS member

18th Feb 2004, 12:23 am	#2
humorist2751 Pentode Join Date: Nov 2003 Location: Chelmsford, Essex, UK. Posts: 121	BRC 1500 stock faults Poor sync on BRC/Thorn 1500 series chassis was usually caused by failure of R44 (sync. separator screen feed resistor); the cure was to replace this with a component of at least 1 watt rating. It's half Lombard Street to a china orange (as my Dad used to say) that any 1500 still extant will have had this done long ago! I guess this could well be true for many stock faults - but it's still good to know about them. Somebody has already mentioned the no sync fault so here are a few more. Weak video with lots of streaking: R40, R41 video output stage load resisters gone high or o/c. Both can be changed out using 1 x 3.3k and 1x 3.9k 1w resisters. Same symptoms can also be caused by electrolytic cap C37 (64uf) which feed video to base of video output transistor. For poor frame linearity and frame jitter change out R101 & R102 both 18k 1w resisters. These are fitted across the primary winding of frame output transformer. Frame cramp on bottom of picture with poor frame hold. C89 (1uf) dried out. This capacitor smooths the boost line feed to the frame oscillator. __________________ Regards David F. Symes