Eumig 824 circuit diagram

[Brian Gainsford]

Hi all, I'm a new member living in Australia seeking some technical assistance please. I have just bought a Eumig 824 believing it was a working machine only to find there's no power to the lamp socket. There is a circuit diagram in the users manual but it appears to be mainly for the components on the audio circuit board and not much else. Would anyone be able to help with complete electrical diagrams of the entire machine? I have checked the lamp socket which appears to be fine. It's the 12v that's missing. I'd appreciate any help offered. Thanks, Brian

[Joseph Banfield]

I can't help with the circuit diagram but will tell you that you should start by just changing out the lamp socket to eliminate the possibility of coroded or broken contacts inside the socket. Also check the lamp with an ohm meter to check for a good filament and clean the pins too...those halogen lamps can look perfect but be open circuit, which is more common than you would think.

There is a small switch that is located to the left of the main control knob that will be visible when you remove the cover to expose it. That tiny switch is controlled by a small nylon rod that rides on the main nylon control cam. Clean those tiny contacts.

Lastly, but highly unlikely, would be the power transformer. Set your meter to measure AC volts; trace the lamp wiring back to the transformer and look for 12 volts there. If 12 volts AC is not found at the transformer you're done because that would indicate an open secondary winding. But I've never seen that in actual practice.

Also, if measuring for 12 volts at the lamp socket, the projector main control must be switched to the "forward run position with lamp" or you will only read about 2 volts AC on your meter...12 volts can not appear at the socket until the projector is running in forward and set with the lamp on. And be sure your meter is set to measure AC volts, not DC!

[Maurice Leakey]

May I also suggest checking the Dim/Bright selector switch. (To the left of the Volume/Tone controls.)

[David Strelitz]

Totally on the same page as Joseph. Turn off cut the cables to the lamp holder, turn on select full forward measure voltage on the cables. If nothing then investigate the hidden wafer switch. I don't have time to take the back off one of my 824s as I'm filming in London shortly but I can take a look at the transformer outputs on Tuesday (away tomorrow) if you don't get sorted and post a pic of the 12volt outputs.

[Brian Gainsford]

Thank you gents for your suggestions. I will investigate all the options mentioned and provide some feedback.

[Brian Gainsford]

I'm pleased to report that 12 vAC has been found and the lamp socket is in good working order. I have ordered some lamps as the one that was in a new box and appeared new was in fact dead.

On removing all the covers I have found a lot of white dust/aluminum corrosion which I have carefully started cleaning up with a vinegar/water solution. Not sure if others have experienced this or if it's a result of living in a hot and humid climate on the east coast of Australia. It appears the mechanical parts all work, with the gears and levers being well greased and in good condition. It's evident the projector has been worked on before so it may have been serviced at some point. Unfortunately the previous owner is dead so I can't check any detail with him.

There is "motorboating" noise coming from the speaker which was quite common in most audio equipment from this era. Have any of you managed to overcome this effect and if so do you have any recommendations?

Thanks again for the prompt replies to my questions. I look forward to learning from the forum and sharing my experiences as I progress with this new found hobby.

[Joseph Banfield]

Ah yes, the lamp that looks new to the naked eye but does not work. As I said, it is more common than you think.

The motorboating could be caused by a dried out electrolytic capacitor...often the large one but could be any of them. But before changing out any capacitors you may want to exercise and spray some contact cleaner on the switch on the circuit board that is activated by pushing the red button to engage the recording mode...you may have to push it as many as 20 or 30 times. Start there and see if you get anywhere. Those recording switches become oxidized after a time and cause all sorts of audio issues.

[Brian Gainsford]

Thank you Joseph, I'll look at that and try your suggestion.

[Renzo Dal Bo]

Here is the EUMIG 824 Circuit Diagram taken from the German user manual.

[Brian Gainsford]

Thank you Renzo for the cct diagram you've posted. It is the same as the one I have but I believe it only relates to the audio system. Now that I have found the the 12 vAC to the lamp I should be fine for the moment and until the lamp arrives, when I can finally test the projector and at which point I may need more help. Regards, Brian

[Erik Snel]

You can disassemble the switch on the amplifier and clean the slide and polish the contacts. 9 out ot 10 time sound will be better. keep in mind that the capacitors probably have gone bad. the giggest on the pcb is the worst of all, when this one goes bad you get a short in the amp and the fuse blows. when this happens you can test it by replacing the fuse an cut the capacitor out, when the fuse does not blow you know it was this capacitor. it would be better to replace all of them.

[Brian Gainsford]

Thank you Eric, I will investigate the items you have mentioned and see what improvements result.