Patt 743 remove lampholder

[stokey]

Can anyone give me a quick guide to disassemble a Patt 743?

 

I need to replace a lampholder but can't work out how to access the underside of the lamptray to remove the retaining screws.

 

Maybe I am being dim!

 

Thank you

[gareth]

It'a been a fair few years since I last took one apart! But I've disassembled a few of them over the years, and from what I remember you have to pretty much dismantle the focussing mechanism in order to be able to lift the spiral focussing gear out of the lantern with the lamp tray attached to it.

[Don Allen]

Before you start, make sure it does not have a fibreglass lead.

You remove the lead screw drive. There is a nut that is removed by a set of flat nose pliers as it is a slotted nut, hold the focus knob when turning the nut. The metal leadscew bearing or support is held in place with three small self tappers. If there is a spacer on the front of the lead screw, held in place with a circlip, make sure it goes back in the same place, as it stops the lampholder getting too close to the front lens. Once you have removed the lead screw you can pivot the lampholder sideways to get at the screws underneath. It is a while since I have replaced a lampholder, I may take out the other non lead screw side as well. I place all of the parts in a line as I remove them to make sure it is reassembled in the correct order, as there are also washers.

[themadhippy]

make sure it does not have a fibreglass lead.

Do you mean asbestos? whilst fiberglass aint nice stuff its not really a concern

[kitlane]

make sure it does not have a fibreglass lead.

Do you mean asbestos? whilst fiberglass aint nice stuff its not really a concern

 

I read the word 'fibreglass' but in my head it was translated into 'asbestos' because I subconsciously knew that was what was meant.

[Don Allen]

The brain thought asbestos but the fingers typed fibreglass ! Been a busy week.

[stokey]

Thanks very much everyone. I had a feeling I would need to dismantle the focus mechanism.

 

Fortunately this unit has been rewired before, so it has an up to date high temp cable.

[gareth]

On the subject of asbestos - depending on the vintage of the unit, beware of any insulating discs between the lamp holder and lamp tray. At my old venue we discovered that a whole bunch of 243s, 252s and 293s had asbestos discs in that location - the whole lot had to be stripped down and decontaminated by a specialist contractor. I've never personally encountered a 223/743 with an asbestos insulating disc - but that's not to say they don't exist.