Amplifier issue Eiki EX 6000 Pedestal

[Paul Repar]

So about 2 years ago, I purchased a 16mm Eiki EX 6000 xenon pedestal projector,when I purchased it, I knew before even getting back to my home the amplifier had some sort of damage,and yes I know i can get audio via the sound cell,which I have,but i want this to be fully operational,I have searched a replacement board and found one last year,only to find out it was modified and would not work,month later I found a tech in NC who would replace the damaged board from an Eiki 4000,after spending money, and he did not have a pedestal unit to test,this newly replaced board still did not output sound.
So I decided to use the limited knowledge on electronics and meter caps,check the wiring,naturally fuses,voltage from the transformer in the pedestal to the board is correct.The caps were checked,but replaced them anyway, the exciter lamp does light up,Studying as much as I can with the schematics I went through anything and almost everything my limited knowledge of electronics i could.I did meter a few resistors that seem to be bad,so I have ordered the right ones,not sure if this will do it.But if anyone else out there,knows,or can,fix,test,diagnose this issue please PM me...everything else with this 6000 works fine,just this amplifier,i currently have this amp connected to the single pedestal speaker, and furthest I have come was some pink noise/low hum from the speaker, which did not occur before.Photos are posted of the amp,anyone out there have a spare?would be great,any other knowledge from electronic techs would be helpful!

[Mark Gulbrandsen]

All you need to do is add an I to your name and open up a shop!

Getting to the amplifier

1. Never measure resistors when they are in circuit. Always unsolder one end for an accurate reading. You need to be within 10%. There are often other components in parallel with resistors that affect readings.

2. That amp has a mic input. See if that works. Try feeding a low amplitude line leve sine wave signal into it if possible, or plug in a dynamic mic if you have one. That can verify if the actual amplifier is working or not. An oscilloscope, or signal tracer is very useful for tracing the signal through the amp stage by stage.

3. Since the pickup is either a solar cell or photo diode, you need to figure out which, then you can inject a signal into that input on the amplifier. The exciter lighting up is good, but is the scanning beam illuminating the sound track? Is it bright enough and is the scanning lens aligned correctly?

4. Since you got pink noise through it somewhat, the amp may actually be ok. So take a very close look at the scanner. Is the slit lens cloudy? Can you visually see a slit of white light falling on the soundtrack? Is the exciter lamp the correct one?

Can't think of much else, except Back in the 70's I was the AV repair guy for a large school district. They had just over 600 Eiki's plus a little over 200 Kodaks. I never had an amp fail in any of the Eiki's, but I had several fail in the Kodaks.

If you can't figure it out, call Full Aperature Systems, also in Chicago. James Bond May be able to help you, or refer you to someone that can.

[Paul Repar]

As to your tip for number 1...correct I have done that and noticed 4 resistors I am not getting a reading from on my multimeter
2.The Mic and Phone output also will not give any sound, I do not own an oscilloscope, my knowledge is very basic on electronics, the amp board faces down so I am not able to test it will it is connected to the machine with power,cable lengths and where it sits cannot be done.
3.The exciter lamp illuminates at full brightness, the slit end was checked and cleaned prior to me checking into the amplifier.a seperate jack that comes from the cell itself
does output sound when plugged into my outboard pre amp mixer and receiver,the slit lens is not cloudy,the exciter is the required BRK 4V .75 which is required per the manual.

This amp did take a hit way before I bought this machine, so I knew something needed to be fixed,the board had stress cracks,but after all I have been through with trying to figure it out is replace the 4 resistors,finding another amp,which is specific to the 6000 is not east...I will try to contact Full Aperture and hope they have an answer,they are local,so it is worth a try.Thanks for some insight Mark

[Mark Gulbrandsen]

If it took a hit, then some copper traces may be cracked open or intermittent. But the exciter supply works and if necessary you may have to convert it to use an external PA amplifier and feed the output of the solar cell into a mic input of the PA amplifier assuming it has a solar cell. Should be able to tell by looking at the schematic. You'd be amazed how many theaters in Chicago ran that way until Dolby came out.

[Paul Repar]

The board that had cracked traces was replaced last year from a tech in North Carolina,he used a 4000 Eiki Xenon board NoS and the boards are virtually identical,but as stated in my original post he did not have a pedestal to test, so I took the chance,and still did not work,and yes I have used the cell to output sound and that end works, but my point to this is I really want everything on this machone to be operational,hence the reason I want to have this amp working.Thanks for your input,appreciate it!