Kodak Ektapro 9020 Lamp issues

[studio64]

My projector even with new bulbs keeps switching between the 2 lamps and finally shuts down. Service manual indicates that they need to OHM out at 1.5 or less but even new ones are around 1.8 to 2.4. Not sure how to fix this?

 

[koraks]

Ohmic resistance of the cold bulb doesn't say much. If the bulbs light up, at least for a while, and they keep doing that time after time after turning the projector on, then it's safe to assume the bulbs as such aren't the problem, provided that the correct type is installed.

IDK what kind of safety mechanisms there are present in this projector that might cause it to switch between bulbs and/or shut down. Possibly it has something to do with failure of such a circuit, causing a safety feature to engage inadvertently. Evidently, the projector is equipped with failure detection systems and it seems likely (at least to me) that the problem is related to these.

I'd start by cleaning out the machine to ensure that no dust etc. is affecting dissipation of the heat of the bulbs. Thermal problems can very well explain this kind of behavior and given the age of these machines, buildup of dust and grime seems plausible.

And welcome to Photrio!

 

[studio64]

Attached is the service manual. On 5-12 is where I started, my bulbs are at 1.6 or greater even being new.

 

[koraks]

Like I said, I wouldn't attribute much meaning to the static resistance you measure on the cold bulb. 1.6-2.5R sounds plausible. If you measure across the contacts outlined in the service manual you linked to, it's entirely likely (virtually guaranteed) that you measure a little higher than the manual says depending on contact resistance at the measurement points etc. The fact that you're reading maybe 1R on the high side doesn't say much.

Have you cleaned the machine out yet?

Your problem likely relates to this black-box functional module:

Physically, I expect it's located here:

If you can find a schematic of that part, it might be possible to come up with some hypotheses of what's going on. Might be something simple as a capacitor that's aged beyond spec.

 

[studio64]

Machine is very clean, doesn't look like it was ever used much.

 

[studio64]

I think this is the board.

 

[koraks]

It's at least part of the power supply. Without a schematic there's not much I can say about it other than that.

 

[studio64]

any ideas where I might find a schematic? I've searched.

 

[koraks]

Not really; I'm sure someone, somewhere has a set of schematics of this unit.
What I usually do in a case like this is isolate where the problem likely is, and then try to draft my own schematic based on some good photos of both sides of the PCB that I overlay and align, combined with some measurements on the PCB.

 

[Sanug]

My projector even with new bulbs keeps switching between the 2 lamps and finally shuts down. Service manual indicates that they need to OHM out at 1.5 or less but even new ones are around 1.8 to 2.4. Not sure how to fix this?

It is difficult to measure such low resistance properly. Your result look quite okay for me. You always have calculate an additional resistance at the lamp contacts and the measuring cables and plugs.

Maybe there is a problem with corroded contacts of the lamp sockets. At the first place, I would replace or clean the lamp sockets prior to troubleshooting in the electronic circuit of the projector. Second, I would check the soldering at the lamp outputs of the electronic board.

 

[perkeleellinen]

The Ektapros switch to the second bulb if the first fails, the idea is that even with a blown bulb a slide show would not be interrupted. Does the machine which back and forth between bulbs or does it switch once and then shutdown?

 

[Chan Tran]

Also on that note do the 2 LED's L1 and L2 turn on? They are to indicate lamp failure.