DeVere 504 hot smell

[polyglot]

Hey all,

I've got a 504 (pretty old, looks like this (https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRYHRVw8qJzbL0tW157DcKMJnsCLLtQbgR9M1tAYzp1Fqc6Y1rOLg)) that I've been using for a few years and it works great, but it has a really nasty hot smell coming from the head when turned on for more than about 20 seconds. It's a mixture of burning dust (understandable given how little use it gets) and burning plastic, which worries me. It completely stinks up the darkroom with an 8-stop (256 second) exposure!

Feeling around inside the head, I couldn't feel any of the electrical connections overheating. The fan is running fine, though annoyingly loud and whiny. It has an ELC bulb (24V 250W), which I'm pretty sure is the right type for the head. The diffuser doesn't seem to be getting hot, and the smell is definitely coming from the head - it's strongest in the fan exhaust. As far as I can tell, the only things getting really hot are the bulb (obviously) and the wires directly connected to it, presumably from conducted heat.

Are the DeVere heads known to have any common overheating faults or unreliable connections?

thanks...

[bob carnie]

Loud and whiny ,, the fan sounds like the culprit.. Odessey Sales has parts if its not an off the shelf item.

[LabRat]

I'm with Bob on the fan, but also poke around to see if wire insulation (somewhere else in the head) is maybe making contact with something hot, even a warm/hot metal panel... Run it without a cover hot, and quickly turn off and look for "magic smoke"...

Tip; when vinyl wire insulation get overheated/burns, it smells really bad, and will smoke like a NASCAR fire... (The bulb leads are usually teflon or fiberglass, so look for other wires or plastic parts that might have been dislodged...)

Steve K

[Tony Lakin]

Hey all,

I've got a 504 (pretty old, looks like this (https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRYHRVw8qJzbL0tW157DcKMJnsCLLtQbgR9M1tAYzp1Fqc6Y1rOLg)) that I've been using for a few years and it works great, but it has a really nasty hot smell coming from the head when turned on for more than about 20 seconds. It's a mixture of burning dust (understandable given how little use it gets) and burning plastic, which worries me. It completely stinks up the darkroom with an 8-stop (256 second) exposure!

Feeling around inside the head, I couldn't feel any of the electrical connections overheating. The fan is running fine, though annoyingly loud and whiny. It has an ELC bulb (24V 250W), which I'm pretty sure is the right type for the head. The diffuser doesn't seem to be getting hot, and the smell is definitely coming from the head - it's strongest in the fan exhaust. As far as I can tell, the only things getting really hot are the bulb (obviously) and the wires directly connected to it, presumably from conducted heat.

Are the DeVere heads known to have any common overheating faults or unreliable connections?

thanks...

The DV504 was made in the UK, could it be that the fan is spinning the wrong way round in your hemisphere?:D

Over 4 minutes does seem like a long time to run the lamp continuously.

[Luis-F-S]

The fans in these heads are typically computer type fans. Probably similar to an ETRI - AC Axial Cooling Fan 99 XU 2182 : 92mm x 25mm 115v, though the voltage is probably different on yours. They came both 120 & 220 v. I'd take it out and see the type, and then check on line or the Auction site to see if you can find a replacement (quickly & cheaply). The socket/leads should be an off the shelf item available from an electrical supply house. On my 5108 it's a Buhl QHV-1 GY5.3 Lamp Socket Assembly at around $4.80 each. Hope this helps.

[ic-racer]

Take it apart an see. Maybe some plastic or rubber has deteriorated and has fallen on the lamp. Otherwise consider a new socket with wires and a fresh lamp. If the unit is old, it would probably benefit.
138916

[Peter De Smidt]

They are very modular. You should be able to dismantle it enough to check it out. Make sure the vent areas are clean. Look for any kind of heat damage. Is the IR glass in place before the mixing chamber? I have a newer model color head, though, and they might not be the same in that regard.

[polyglot]

Yeah, I've had it apart and a good look through it (my initial hypothesis was a poor/ohmic electrical connection) and nothing is obviously where it shouldn't be. I've previously replaced the lamp and the only thing on it is dust that it's inhaled.

Replacing the fan is probably a good idea, if only to reduce the annoyance factor.

thanks everyone.