Ramsey Electronics SCA1, Руководство пользователя

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SCA1
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17
TROUBLESHOOTING GUIDE
If your SCA1 doesn't work, a thorough check of the component placement will
usually turn up the problem. Checking your work backwards through the
assembly steps is very effective in locating placement errors. If the unit appears
to operate correctly, but just doesn't seem to pick up any SCA programs,
maybe there are no FM stations in your area that are transmitting SCA signals.
Sometimes a phone call to a radio station Chief Engineer will steer you in the
right direction, but be sure to let him know you are a hobbyist and not out to
steal the SCA programming!
Lastly, interconnection to your FM receiver is probably the area where most
problems can develop, and it's also the area where we can offer the least
amount of help. In this case we can only suggest that you verify that the SCA1
does indeed operate using an audio generator as outlined in the Testing
section of your manual. The use of your SCA1 with the Ramsey FR-1 FM
broadcast receiver is the only combination that we here at the factory have any
familiarity with. Here are a few common problems along with solutions which
may help in simple troubleshooting:
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PROBLEM: Occasionally good but erratic operation.
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SOLUTION: Check very carefully for poor solder connections.
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PROBLEM: Loud AC hum or buzz.
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SOLUTION: . If you are using a 9-volt AC power adapter, the adapter
design may not be of sufficient quality for this application. Try bypass
capacitors, a different adapter, or a well designed and filtered DC power
supply.
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PROBLEM: Signals have unpleasant distortion or tune in "funny".
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SOLUTION: Signal level into the SCA1 is too high. Reduce the level by
adding a resistor in series with the cable to J1 (try values from 1K to 22K).
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PROBLEM: VCO oscillator measured at TP 1 is inoperative or wrong
frequency.
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SOLUTION: In addition to checking solder joints, be sure that R3 and C11
are the correct values. These are the frequency determining components.
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PROBLEM: Unit receives when R1 is adjusted, but drifts away or is very
noisy.
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SOLUTION: Signal level into the SCA1 is too low. Try a different point
within your FM receiver for connection of the SCA1.