Eiki NT2 sound problem

[Jonathan Wood]

Hi all,
Ive just got hold of an Eiki NT2 which is in great condition except for a strange issue with the sound . The amp is totally dead , no hum , hiss or exciter lamp. The fuses are both good as is the exciter lamp itself . All the connectors inside seem fine . Then after about half an hour it suddenly comes to life and it works fine . I’ve noticed what looks like a large capacitor on the side of the amp module , does anyone think this could be the problem? It seems like a power supply issue and I’m assuming this is the main cap in the rectifier . Any help or advice will be very gratefully received. Best wishes, Jon

[Brian Harrington]

Have you given everything electrical inside that has to do with sound a good cleaning with contact cleaner? Solid state unlike tubes don't need any warm up time to get going, so I'm assuming a bad capacitor would either work or not, and not start to work after warming up. I say that with very little knowledge of capacitors so you may take it with a grain of salt if you wish.

I'm from the school of thought that if something works intermittently it probably indicates a loose or bad connection somewhere. My experience with contact/electrical cleaner has been close to wizardry in what it has accomplished. Can't hurt to try, especially if you already have a can at hand. I like to eliminate simple reasons for failure first before moving on to the more complicated ones. KISS principle. Occam's razor, etc, etc, etc.

I have an SNT model but never had to poke around in the back of the machine much except for the occassional lube. (Knock on wood.)

Not sure if there are any micro switches involved in turning on the sound but I've had to fix micro-switches in Super 8 machines before. They can be flakey, and in my case the entire machine would shut off for a second then start up again in the middle of a reel! With all the moving parts in a projector, the vibrations can for a split second move contacts to a position where the contact is no longer conducting electricity -- at least that was my theory for the problem I had.

Simpler than using the contact cleaner -- work all the sound switches many times on the machine since this will self-clean contacts, but if it comes back, then contact cleaner will be necessary, since where did the dirt go when working the switches??? Though the "dirt" is actually oxide and the cleaner should "dissolve" it for lack of a better word.

[Steve Klare]

Agreed with all, and maybe I'll add that sometimes really old printed circuit boards have old, oxidized solder joints that aren't really making solid contact anymore and a lot of good can be done with a hot iron and fresh solder.

Capacitors gradually lose their capacitance with time (especially electrolytics), but they don't come and go.

[Nantawat Kittiwarakul]

First thing first, can you make that issue reappear?

Would be hard to investigate further if that's kinda once occurance.🤔 A tad easier to deal with if that happens intermittently.
The good thing about Eiki NT projector is its modular design. You can literally have the entire amplifier unit removed in 5 minutes with a help of a philips screwdriver. After that it's just a matter of blasting all volume/switch inside with a can of contact cleaner. This should more than likely to take care of the issue.

[John Burgess]

Hi Johnathan
I would try and remove the amplifier and check the 9 pin socket that connects the power etc to it. You would need to use switch cleaner on both male and female parts of it, oxidisation on this important plug could well be your issue.
Good luck John

[Jonathan Wood]

Thanks everyone for your replies and advice , I’ll get the amp out and give it a good dose of contact cleaner . I only suspected the cap as it seems like a power supply issue and it might be possible that the caps leaking and not charging properly, but it seems unlikely it would need half an hour to charge up! !