Knoll Systems service information
The MA850 amplifier does not contain any user serviceable parts inside. If you suspect a problem that may require servicing, contact us at www.knollsystems.com/contact.html, or by phone at 800
Troubleshooting
If a problem is encountered with the MA850, the most expedient procedure is to locate the problem and if possible repair it before requesting service. Be sure to carefully check other system components such as controllers, CD players, volume controls, wiring, speakers, etc. that may be at fault.
Problem | Action | |
Power LED does | 1. | Check that the MA850 is plugged in. |
not light - no sound | 2. | Test the AC outlet with a lamp. |
| 3. | If remote on/off is used, check that |
|
| the trigger voltage is at 12 VDC. |
| 4. | Check MA850 power button on (in). |
Sound cuts out | 1. Verify speaker impedance is | |
|
| Changing speakers may be required. |
| 2. | Check if the MA850 feels hot. If it's |
|
| hot increase cooling - see Installation. |
Sound is distorted | 1. | Turn the volume down. |
| 2. | Check speakers for damage. |
| 3. | Check inputs for proper levels. |
|
| MA850 gain and source output level |
|
| may have to be adjusted. |
| 4. | Speakers may be less than 4 ohms. |
MA850 does | 1. | Push MA850 power switch off (out) |
not turn off | 2. | If trigger is being used, power switch |
|
| needs to be set to off (out) position |
|
| or amp is on all the time. |
| 3. | Try disconnecting trigger jack. |
Trigger does not | 1. | Measure trigger voltage with a volt |
work |
| meter. It needs to be |
|
| to work (current is about 35mA total |
|
| per amp). See page 5 for details. |
Speaker pops when | 1. | Speaker may need resistor placed |
amp turned on or off |
| across terminal. Suggest 2k0 1/4 w. |
|
| Discharges speaker internal cap. |
Installation
Installing the MA850 should be relatively easy. With a bit of planning, the MA850 will give trouble free service for years.
1.The most important consideration when installing the MA850 is cooling. The MA850 has a lot of power packed into a small chassis size. When installing it in an equipment stack, it should be the top component. It needs at least
2.Amplifiers should always be the top components in system.
3.If MA850 channels frequently shutdown due to overheating, install a fan directed up from the MA850 bottom center.
4.Never operate the MA850 on its side, as the cooling potential drops significantly when operated on the side.
5.Connect the MA850 inputs to the source component outputs with good quality, short as possible RCA jack cables. Connect each channel individually.
6.Connect the MA850 speaker outputs to speakers using good quality speaker wire. Minimum 16 gauge copper wire is recommended with 14 gauge minimum for runs over 30' (10m).
Note: Ideally the MA850 likes
7.Individually adjust the channel gains as required. Ideally, all gains are fully on (fully clockwise).
8.Make sure the speakers in each room are connected in phase with the amplifier + going to the speaker + . Out of phase speakers give unstable imaging and poor bass response.
9.Connect trigger if being used to a 12 VDC source (about 35mA) using a 3.5mm mono jack. 5 VDC triggers will not work.
