 Posted: Sun Jul 29, 2007 11:35 am Post subject: |
|
| Check if the transformer has no embedded thermal cutout.
The symptom you describe sounds like an thermal type of problem. Put your voltmeter on the AC low voltage side of the transformer, turn it on, then when the lamp goes out check if there is still a voltage present if not, your problem is in the transformer. if voltage is ok, your problem is between the low voltage side of the TX and the circuitery downstream to the lamp. Also check the lamp socket that the prongs make good contact because these get very hot during service. |
|
| Posted: Sat Jul 21, 2007 3:01 pm Post subject: Overhead projector help |
|
| Hello all,
I've been having a problem with an overhead projector for the last few days. It runs fine for approx. 3mins 10secs then the bulb cuts out for approx. 45secs. I tested this for about 40mins and the times never varied more than 10secs from the approximate figures I gave. I've tried with a couple of brand new bulbs and got the same problem. Unfortunately there are no manufacturers marks anywhere on the machine but I believe these projectors are quite standard items. I'm not too hot on electronics but I think I can identify the key items in this photo (transformer, fan/motor, power connections/switches): 
I had assumed there would be a thermistor in there somewhere but I can't locate it. Any help appreciated. |
|