Ferguson 3645 (BRC1400 chassis) raster but no sound or vision - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Focus Diode · 19th Sep 2006, 8:21 pm

The PY801 can be fitted in place of the PY81 and PY800.

Thankfully the LOPT is very reliable in these sets and is the last component to suspect in the event of line output stage trouble, which cannot be said of certain other makes.

The tripler can fail if it's the "open" variety, but diagnosis is instant through the smell they can give off!

I've had very little trouble with the line output stage. One odd 625 only fault worth mentioning is a herringbone pattern covering one half of the screen. The line output valve's Screen Grid decoupling capacitor C115 is responsible. Might be a 1uF 350V or 0.1uF in this posistion.

Also worth mentioning the width control R142 and its feed resistor R143. Respectively they are 1M and 330K. They can overheat causing a burn up. Replacing the control with a 2M2 pot and changing R143 to 680K is recommended.

Look forward to hear about the KB set.
Well done again!
Brian

tvden · 19th Sep 2006, 11:41 pm

Brian many thanks for the extra info on this set I expect I will do some more work on it re the mods, as I have got he hang of this chassis now I will look out for another 1400 with a bigger screen as this is only a 16", the KB Aristocrat set is original IE no parts have been changed, I have been useing it like this for some time but some of the components are tired and need changing, but its viewable as it is, I hope to sort it sometime over the winter but another thread needed for this

19th Sep 2006, 8:21 pm	#21
Focus Diode Octode Join Date: Jan 2006 Location: Borough of Gateshead, UK. Posts: 1,420	Re: Fergi 3645 BRC 1400 chassis help needed The PY801 can be fitted in place of the PY81 and PY800. Thankfully the LOPT is very reliable in these sets and is the last component to suspect in the event of line output stage trouble, which cannot be said of certain other makes. The tripler can fail if it's the "open" variety, but diagnosis is instant through the smell they can give off! I've had very little trouble with the line output stage. One odd 625 only fault worth mentioning is a herringbone pattern covering one half of the screen. The line output valve's Screen Grid decoupling capacitor C115 is responsible. Might be a 1uF 350V or 0.1uF in this posistion. Also worth mentioning the width control R142 and its feed resistor R143. Respectively they are 1M and 330K. They can overheat causing a burn up. Replacing the control with a 2M2 pot and changing R143 to 680K is recommended. Look forward to hear about the KB set. Well done again! Brian

19th Sep 2006, 11:41 pm	#22
tvden Retired Dormant Member Join Date: Oct 2003 Location: Halesworth, Suffolk, UK. Posts: 413	Re: Fergi 3645 BRC 1400 chassis help needed Brian many thanks for the extra info on this set I expect I will do some more work on it re the mods, as I have got he hang of this chassis now I will look out for another 1400 with a bigger screen as this is only a 16", the KB Aristocrat set is original IE no parts have been changed, I have been useing it like this for some time but some of the components are tired and need changing, but its viewable as it is, I hope to sort it sometime over the winter but another thread needed for this