When I had the mainboard removed when I installed the extra memory, I noticed some caps by the RCA connectors that according to the FAQ shouldn't be there as this was a Mk2a, so they're probably something else, I thought. This was on my spare Empeg. Then when I did my main Empeg, I checked the caps, and they weren't there. So obviously (at least to me...) the FAQ must be wrong (sorry, Tony...) as my spare is also a Mk2a. Otherwise I guess I would have had some problems installing the extra memory... So, anyone else that have experienced this?

Stig

The title of this thread caught my attention, I taught it was going to be about how Paul had hooked up one of his empegs to a Symmetrix - though I think he would need quite the RAM & alternator upgrade.

I think I could deal with the RAM. It would be the partitioning for the scratch and metadata that would be the issue. As for power, well, that is an issue as well. I guess I would need to upgrade to an SUV or perhaps an airplane...

the FAQ must be wrong

As I recall, that FAQ entry was based on the words of Hugo himself, so please direct your accusations accordingly.

Well, he _should_ know what he's talking about, I guess, but in this case... Well, I don't know... In this picture it looks to me like there are two caps there...



Stig

Somewhere, in 2004, I managed to pin Hugo down on this, and he posted (on the BBS, or I copied it to the BBS) that on Mk2a they used the right value capacitors, so removing them is not necessary. On Mk2 units the value was far too high or something.

The Search function might find his actual words.

EDIT: ahh.. here it is:

From: altman
Received: 11/02/04 12:07 PM

I believe (hazy memory) that the value was changed on the mk2a to a lower capacitance, hence they didn't cause the rolloff problem (but did still attenuate EMI, which is what they were there for).

Hugo

-ml

Ok, thanks. You wouldn't happen to know the correct value? I have a problem with alternator whine on my main unit, which doesn't have the caps, so I could try to add the caps and see if it helps. Or I could desolder one from the spare and measure that...

Stig

Okay, I've clarified the FAQ based on what Mark just said.

Don't try replacing the caps on the Mk2 unit to solve your alternator whine problem. Just insert the 2a into the sled and see if the whine goes away. Since the 2a has the right value caps already, if the whine doesn't go away then the caps have nothing to do with it and it's more likely one of these problems.

It's not a Mk2, they're both 2a, and yes, I know about all the things that could cause it... It might also be my amp. It's an old Alpine 4x25W, running as bridged 2xSomething... It's just that it's such a PITA to try out everything in the faq to get rid of it and it's not that irritating...

Stig

Right. My point is that if you have a second empeg WITH the caps, and they're the correct ones, then try it in the sled before wasting the time to try and mess with the caps on the first empeg. Much quicker diagnostic procedure.

I know. I think I tried it once, but I can't remember the result...

Stig

Well, try it again just for kicks. But those caps should have no effect whatsoever on low frequency alternator whine.

-ml

I would be very careful to check that they are in fact caps: there are a couple of resistors in this area as well. However, I have found them on early 2As, so it could be yours is one of them. Removing them is not difficult but requires a fine iron and PATIENCE to get them off without damaging anything else. The FAQ is quite good on this topic and can be relied upon (as can the whole FAQ, to be honest, thanks to the Master of the FAQ.

As a point of note, I found that a number of customers reported that earth loop hum reduced drastically after their removal. This was the case on 5 seperate machines that I repaired and serviced (according to my notes).

Could possibly be one of the early ones, and I'm quite sure they're caps. And removing them wouldn't ba a problem at all. I have a tweezer soldering iron...

I tried my spare (with the caps) and to me it seemed to be reduced slightly with the spare...maybe...

When I get the time, I'll try to use another ground for the Empeg. Right now I'm using the car's ISO-connector.

Stig

I tried my spare (with the caps) and to me it seemed to be reduced slightly with the spare...maybe...

It not likely to be related to the capacitors then. You need to start going through the ground loop elimination steps for your amp installation.

When I get the time, I'll try to use another ground for the Empeg. Right now I'm using the car's ISO-connector.

Try attaching a thick ground wire to the screw hole on the back of the sled, and finding a proper ground point on your car's frame. Tips on the proper ground point can be found here.

Thanks, Tony. Will do...sometime... It's just such a hassle to get the sled out (and back in) along with all the cables for the second HU and GPS.

Stig

Greetings!

For the sake of "just testing", it might be possible to secure a wire temporarily to the front of the sled and run it through the passenger compartment and door to a ground in the doorframe or, worst case, the ground. While not a permanent fix, it should help show if grounding the sled will help or not. Thoughts?

Very good idea, Paul.

Of course, if it doesn't change anything, he'll still need to pull the sled out to check for loose wires and such.

I think I have tried it once before with the wire. I think I tried it from the sled to the ignition lock. And I think I checked for loose wires when I installed the GPS. That's when I installed the amp and ran the other HU through the Empeg instead of running the Empeg through the HU and using it's built-in amp. That's also when I got the alternator whine. Didn't have it before I used the external amp. When I used the amp in another install in my first car, I didn't have any alternator whine either, but it is about 10 years ago, so it could be that some caps in the amp has dried out and that's why I get the noise now... I guess I could borrow another amp and see if I have the noise with it, too. Decisions, decisions...

Anyway, thanks for the help and suggestions.

Stig

I think I tried it from the sled to the ignition lock.

The ignition lock is not a proper ground point. Please read the link I supplied.