Manley SLAM! - Manual (Page 21)

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. 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 or its resistance meas-
ures higher than 2 ohms. 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, it works. Some-
times fuses just blow for unknown reasons.
LIGHTS BUT NO SOUND - First try plugging the in and out cables into each other or some other piece of gear to
verify that your wires are OK. If not fix them or replace them. Assuming that cables passed sound - it probably is still
a wiring thing. The output XLRs are transformer balanced which require both PIN 2 and PIN 3 to be connected some-
where. When driving an unbalanced input ( inserts on some consoles) PIN 3 needs to be grounded or connected to PIN
1. Same with the unbalanced 1/4 inch jacks - if driving a balanced input you can’t ignore the negative side. It needs to
be connected to the sleeve of the phone plug. Another way to do basically the same thing is join PIN 1 and PIN 3 on the
XLR male at the destination. Easiest way - Use the balanced with balanced, unbalanced with unbalanced. That is why the
options are there.
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 12 dB difference that will certainly look goofy and may tend to distort. The SLAM! has plenty of gain available on
the INPUT control to accomodate -10 dBv and/or one can use the INSTRUMENT input. For -10dBv outputs, use the
1/4” unbalanced jack with the plug pulled out half way. 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. Sometimes on XLR transformer inputs like this unit one has to
connect PIN 3 to PIN 1 and this is easy to do on the XLR cable (it happens with some unbalanced/balanced connections).
ONE SIDE WORKS FINE BUT THE OTHER SIDE IS DEAD - Let’s assume this is not wiring. We are pretty sure
it is the SLAM. If it were solid state you would generally send it back for repair. Being a tube unit, you can probably
find the problem and fix it yourself in a few minutes. Not too many years ago, even your parents could “fix” their own
stuff by taking a bag of tubes down to the corner and checking the tubes on a tube tester - but these testers are hard to
find today. A visual inspection can usually spot a bad tube just as well. 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 we’ve joked
“the vacuum leaked out”. Either way replace the tube. Manley can ship you a tested one for a reasonable price. Before
you pull a tube, pull the power out, let the unit sit and cool and discharge for a minute or two, then swap the new tube in,
then power, then check. Gentle with those tubes, don’t bend the pins by trying to insert the tube not quite right. A little
rocking of them as you pull them out or put them in helps. If the problem follows the tube you found the problem - a bad
tube. No soldering, no meters, one screwdriver - easy. See page 20 for a diagram of tube locations.
HUM - Once again - several possibilities - several cures. Most likely it is a ground loop. Ideally each piece of gear
should have one ground connection and only one. However, the short list of grounds include the AC mains plug, the
chassis bolted to a rack with other gear, each input and each output. The two most common procedures are: try a 3 pin
to 2 pin AC adapter (about a dollar at the hardware store).This while legal in many countries can be dangerous- We went
one better; Method two - On the back panel loosen the GROUND TERMINALS and slide the small metal ground strap
to one side. This is way better than “method one” because it is safer and removes another possible source - the chassis
grounding via the rack. Method three - cutting the shield on one end of each cable. This is done by some studios at every
female XLR to “break” all ground loops. All the other gear in the rack is “dumping” ground noise onto the ground. Try
removing the SLAM! from the rack so that it is not touching any metal. You just may have cured a non-loop hum. Some
gear radiates a magnetic field and some gear (especially if it has audio transformers or inductors) might receive that hum.
A little distance was all it took. Also the remote power supply box will radiate a 60Hz magnetic field so it should be kept
6”-24” away from gear that may be sensitive.
21