Beseler Dual Dichro head

[Rip77]

After using the color head once it appears that the bulb might have gone out. I am no longer getting it to light up or project the negative. I’m just wondering if this is user error or the bulb! I have heard these color heads can be very finicky and unreliable. Any help is greatly appreciated! It was working the other night but was hit and miss when turning on.

 

[mshchem]

Could just be a burned out bulb. Is the cooling fan running? These bulbs will fry quickly without adequate cooling.

 

[mshchem]

Clean up the bulb contacts with some 0000 steel wool or 400 grit sandpaper. It's usually bad connections if the bulb is ok.

 

[mshchem]

CHECK THE WHITELIGHT LEVER. IT NEEDS TO BE OFF FOR THE LAMP TO LIGHT UP FROM COLD START.

 

[Rip77]

Could just be a burned out bulb. Is the cooling fan running? These bulbs will fry quickly without adequate cooling.

the fan does appear to be running but the system does feel warm

 

[Rip77]

CHECK THE WHITELIGHT LEVER. IT NEEDS TO BE OFF FOR THE LAMP TO LIGHT UP FROM

I tried with the lever in downwards position and still no luck

 

[mshchem]

Find a multi-meter check that the bulb filament is intact. Simple continuity test, bulb out.

 

[mshchem]

I tried with the lever in downwards position and still no luck

The filters need to be engaged, ie not in white light mode. Probably just a bad bulb. A generic bulb of the correct type should be on Ebay for $20 or less.

 

[koraks]

After verifying the bulb is in order (continuity test), Inspect the bulb socket. These sockets often wear out, corrode etc. Replace if necessary.

 

[btaylor]

That’s the color head for the 23c enlarger. They don’t have the electronics that plagued the electronically controlled heads for the 4x5 Beselers. Should be a simple fix.
I was having trouble with my Dichro 45 head lighting up and was preparing for a deep dive into the electronics recently, turned out to be simply a broken filament in the bulb. It would sometimes make contact and light, sometimes not.

 

[ic-racer]

If the lamp and power supply are in good shape, may be time to replace the socket.

Omega D5500 Lamp Socket Replacement

One quirk of the D5500 voltage regulator circuit is that when the lamp socket gets oxidized and makes poor contact, the triac goes full on. This places the full 120v line voltage on the socket. Then it arks through the oxidation and fries the bulb before the regulator circuit can cut it back to...

www.photrio.com

 

[Ian C]

1. Make sure that the “White Light Lever” is in the “Expose” position. Occasionally, the lever will loosen on its pivot and the part attached to it inside the lamp house will not stay in position to close the switch that enables the lamp circuit. In this case, the spring of the switch can push the cam plate attached to the lever away allowing the spring of the switch to it’s “open” position, disabling the lamp circuit. This was problem that I had to deal with on my Dual Dichro-S head. I believe that the DGA, Dual Dichro, and Dual Dichro-S heads all have the same “White Light” lever and switch mechanisms.

2. Remove the lamp and check the contact pins for continuity. If there is no continuity, the lamp is burned out and must be replaced. The correct lamp is the 24-volt 200-watt EJL lamp.

https://www.freestylephoto.com/1000300

The DGA and Dual Dichro heads use a 24-volt power supply. The power supplies were made in two versions. The basic power supply is simply a 120-volt to 24-volt step-down transformer. These almost never give trouble.

The second power supply has a transformer with a voltage stabilizing circuit built in. The transformer is robust, but the voltage stabilizer is prone to failure with aging of the components. If the volage stabilizer goes bad, the lamp my not light. In some cases, it will cause the lamp to burn out quickly (due to voltage spikes), making the enlarger unusable.

Here’s the user’s manual for the color head. However, it has no repair information.

Beseler Dual Dichro 23 Enlarger (jollinger.com)

Your comment, “It was working the other night but was hit and miss when turning on” suggests either the white light lever not keeping the enabling switch in the closed position (point 1 above), or a bad bulb-to-socket connection as noted by others. The same symptoms might be explained by bad contact between the bulb’s pins and the conductors in the socket.

If you have the large voltage-stabilized power supply, it can cause such problems. I had the same thing happen to mine. I solved the problem by replacing this with the transformer-only power supply found on eBay. The transformer-only model almost never gives problems. If you do that, you can use an external voltage stabilizer for color work. If you do only B&W printing, then a voltage stabilizer is unnecessary.

 

[mshchem]

@Ian sums this up nicely. I can only think to add. If the Micro switch that controls the white light circuit is suspected a small spritz of WD40 may help.

The bulb pins and sockets are a weak point, clean and adjust. Again probably just boils down to a faulty bulb.

50 year old equipment.

 

[Rip77]

I’ll be sure to give it another try later but very much appreciate all of the responses!