Manley ELOP User Manual download pdf (Page 10)

TROUBLE-SHOOTING

There are a number of possible symptoms of something not quite right, some may be interfacing, others we will touch

on as well. No need to panic. We have sold hundreds of these units and barely any have ever had a problem with hum or inter-

facing to other gear. However, if you suspect a problem the following paragraphs should help.

NO POWER, NO INDICATORS, NADA - Probably something to do with AC power. Is it plugged in? Check the fuse on the

back panel. A blown fuse often looks blackened inside or the little wire inside looks broken. A very blackened fuse is a big hint

that a short occured. Try replacing the fuse with a good one of the same value and size. If it blows too then prepare to send the

unit back to the dealer or factory for repair. The fuse is a protection device and it should blow if there is a problem. If the unit

works with a new fuse, fine. Check the MAINS VOLTAGE SELECTOR if one is fitted. Some of our models are able to have

them and some don’t. It should be set correctly for your mains voltage.

LIGHTS BUT NO SOUND - First try plugging the in and out cables into some other piece of gear to verify that your wires

are OK. Next check the front panel, try BYPASS. If you have sound now it might be a good idea to turn up the output levels to

about 1 o’clock (rather than fully counterclockwise which is “minus infinity”. The XLR inputs and outputs are transformer bal-

anced and floating. “Floating” refers to a very useful feature of transformers where they can be used without a ground reference

- this prevents ground loops before they happen rather than electronically cancel them. It does require that both PIN 2 and PIN

3 be connected (but not to each other). To interface to unbalanced units you should connect PIN 3 to Ground or PIN 1. Brain-

less solution - use the 1/4” unbalanced inputs and outputs to interface to unbalanced gear.

LEVELS SEEM TO BE WRONG, NO BOTTOM - Several possible scenarios. Manley uses the professional standard of +4

dBm = Zero VU = 1.23 volts AC RMS. A lot of semi-pro gear uses the hi-fi reference of -10 dBm = Zero VU. This is a 14 dB

difference that will certainly look goofy and may tend to distort. Often there are switches on the semi-pro gear to choose the

pro reference level. We do not provide that kind of switch because of inevitable compromises in the signal path. If the loss

looks close to 6 dB and it sounds thin then one half of the signal is lost. The cause is probably wiring again. One of the two

signal carrying wires (the third is ground / shield on pin 1) is not happening. Check the cables carefully because occasionally

a cable gets modified to work with a certain unit and it seems to work but its wrong in other situations. If only one side of the

Limiter exhibits this problem, it may be a problem in the Limiter. See the next item.

ONE SIDE WORKS FINE BUT THE OTHER SIDE IS DEAD - Let’s assume this is not wiring. We are pretty sure it is the

Limiter. If it were solid state you would generally send it back for repair. Being a tube unit, you can probably find the prob-

lem and fix it in a few minutes. Not too many years ago, people could “fix” their own stuff by taking a bag of tubes down to

the corner and checking said tubes on a tube tester. These are practically extinct but no prob’. Most Manley gear is two chan-

nel, meaning you can swap tubes to determine the bad boy. Do two at a time just watching that they are the same number. Be

careful - there are some high voltages inside the chassis and tubes can get pretty warm, but if you can replace a light bulb you

should be able to cruise through this. Before you remove a tube, just take a look at them powered up. They should glow a bit

and they should be warm. If one is not, you have already found the problem. The tube’s filament (heater) is burnt out or broken

like a dead light bulb. The other big visual symptom is a tube that has turned milky white - that indicates air has gotten into the

tube, or “the vacuum leaked out”. Either way, replace the tube. Call us, or look for a tube supplier on the internet. Manley can

ship you a tested one. Back to swapping - before you pull a tube, pull the power out, let the unit sit and cool and discharge for

a minute or two, then swap, then power, then check. Gentle with those tubes, don’t bend the pins by trying to insert them not

quite right. A little rocking of them as you pull them out or put them in helps. When the problem follows the tube you found

the problem - a bad tube. No soldering, no meters, one screwdriver - easy.

HUM - Let’s assume it knows the words. Once again - several possibilities - several cures. Most likely it is a ground loop.

The two most common procedures are: try a 3 pin to 2 pin AC adapter (about a dollar at the hardware store) which is better

than messing up the power cable by bending the ground pin until it breaks off. Method two - cutting the shield on one side of

the cable (PIN 1). This is done by some studios at every female XLR to “break” all loops. You may get a loop simply from

the rack. All the other gear in the rack is “dumping” ground noise onto the rack rails. Try removing the ELOP

from the rack

so that it is not touching any metal. You may have cured a non-loop hum. Some gear radiates a magnetic field and some gear

(especially if it has transformers) might receive that hum. A little distance was all it took. A cool method of reducing all sorts of

hum and noise is to use the new 60-0-60 balanced AC power transformers available from Equi=Tech and Furman. It costs more

but works best. Hum is more likely with the unbalanced inputs and outputs because these signals are ground referenced. A

common situation is using the limiter in a way that significantly boosts the low level signals and what may have started out as a

little hum becomes nasty. Check out the gear feeding the Manley or use less limiting and make-up gain.

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Manley ELOP User Manual Page 10

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