8mm Forum: Bolex M8 lamp upgrade

»	8mm Forum » 8mm Forum » Bolex M8 lamp upgrade

UBBFriend: Email this page to someone!

Author

Topic: Bolex M8 lamp upgrade

Rob Watson
Junior
Posts: 22
From: Sheffield, UK
Registered: Apr 2005

posted May 31, 2007 08:00 AM

I'd like to upgrade the big old incandescent A1/7 lamp in my Bolex M8 to something brighter, but I'm struggling to find an appropriate replacement. I would have thought that something like the 24v 250w A1/223 would be an improvement but at 8000 lumens the light output looks to be well down on the 12500 of the old A1/7. Any suggestions?

| IP: Logged

David Pannell
Phenomenal Film Handler

Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004

posted May 31, 2007 11:05 AM

Hi Rob, and welcome to the Forum.

1. Does your Bolex have a voltage adjustment for running on 110-120 volts?

2. What is the maximum recommended lamp wattage?

If the answer to 1 is yes, and the max. lamp wattage is 750W, do as I have done with my Elmo E-80 and Ampro Futurist. Set the projector to 110/120 volts, put a 750-watt, 115-volt lamp in, and run the machine from a 1kVA transformer. I have written reams and reams about this on the Forum, and believe me, you won't credit the difference in brightness! [Big Grin]

You'll get about a 40% increase in light output.

Briefly, the reason you have to go for the lower voltage lamp, is because the filament in the 750w 115v lamp occupies the same area as the one you have, whereas a 750-watt, 230-volt lamp's filament covers a much larger area, and the condenser lens won't capture all the light. If anything, the picture will be duller than the lamp you already have.

I'm a bit biassed anyway, towards these older technology projectors, and I prefer to stay with the original basic design - but then that's just me. [Razz]

Let me know how you get on. Good luck.

Best regards,

--------------------
Dave.

Valves and celluloid - a great combination!
Early technology rules OK!

| IP: Logged

Rob Watson
Junior
Posts: 22
From: Sheffield, UK
Registered: Apr 2005

posted May 31, 2007 11:32 AM

Thanks for your reply David.

The lamp and motor in the Bolex run at 110V. The only lamp listed for it is the 500watt A1/7 (CZX in the US). The voltage drop from 240v is achieved by a massive coiled resistor which gets spectacularly hot, red hot in fact. Running the entire projector from a 1000w 110v transformer would solve that problem but would be an expensive business (in terms of buying the transformer). Also, I'd have thought cooling would be marginal with a 750watt incandescent lamp in a lamphouse designed for 500w. Thats why I was looking at a low voltage halogen alternative.

Rob

| IP: Logged

David Pannell
Phenomenal Film Handler

Posts: 1072
From: Horsham, West Sussex, UK
Registered: Nov 2004

posted May 31, 2007 03:22 PM

Yes. OK!

The scheme was only viable if the projector could accept a 750-watt lamp. Back in those days, some projectors were supplied with a 500-watt lamp, but the nameplate often stated that a 750-watt lamp could be used if desired. Clearly this is not the case with your machine - a pity.

I would certainly not recommend fitting a higher wattage lamp than the lamphouse and cooling system were designed for; and with the series dropper resistor, it is definitely out of the question.

Guess it's back to the drawing board. I'll be interested to hear how things turn out.

The question regarding a suitable transformer would not be a problem, as I have access to many such devices - but it's academic now.

Good luck.

Best regards,

--------------------
Dave.

Valves and celluloid - a great combination!
Early technology rules OK!

| IP: Logged

John Last
Expert Film Handler

Posts: 104
From: Codsall, UK
Registered: Dec 2012

posted March 20, 2013 04:37 PM

I have converted my M8 to accept the 12volt 100watt A1/231 lamp. An old 12 volt transformer from a Eumig projector can be fitted in the base of the M8. I needed to remove the old lamp base and the condenser lenses. The lamp is now secured in position with a simple aluminium plate with a hole big enough for the lamp and 2 holes to secure the plate using long scrws. The light output is better than the the 5oowatt version and the machine runs cooler.

| IP: Logged

Pasquale DAlessio
Film God