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Pioneer SX-939, Some lights stopped working

MAV

MAV

Member
Hello

Suddenly he stereo lamp and the Function Indicator lamps stopped shining. The LED lights are okay I tested with 9V battery. All other lamps work properly. I have tried measuring on both sides of the stereo lamp but there seems to be no voltage (V), the same goes for the Function Indicator lamps. Anyone have an idea where to troubleshoot? /greetings Mathias Sweden

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Cycle the DIM / Bright Switch a few times. The board it's on has 2 different circuits. An AC and a DC circuit. DO NOT MIX THEM UP! Bad KARMA:no::no: Make sure you have voltage going thru it to the lamps.
 
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Pin 2 of the aws-068 bright / dim switch assembly feeds those lamps.
it is fed by pin 3 incoming DC, then goes through the two diodes and back out pin 2.
The switch shorts across the two diodes.

it is all part of that problematic bright / dim switch assembly.

WAYYY too much current through very small switch contacts.
 
Hi, I have measured AWS-068, between 2 and 3 and there it is 6.9 V AC and between pins 1 and 2 also 6.9 V AC. Pin 3 and and ground 0V DC and pin 2 and ground also 0V DC. Can you say from this measurement that there is no DC voltage and therefore the lamps (FM, AM, Phono1 ,, etc) do not work?
 
Power off. Check the diode string across Pin 2 and pin 3. Check fwd and backward, and with switch IN and OUT. (Rule out all variables).

Go back to the Power supply, power up, and check voltage of pin 2 on the power supply board (AWR-052). Should be about 7.5vdc. If AC, then check D-11 on the AWR-052 for a short.
 
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I replaced the D11 with a new 1N4004G diode then i measured pin 2 on AWR-052 (056) and there is no 7.5 V DC. The multimeter shows 0.0. It is also 0V DC on both ends of the diode D11.
Only AC voltage between pin 1 and 2 and pin1 and 3 is about 6.9 V AC.
 
Finally found the bug (puh). All components are okay but there is a break in the copper trace between the fuse and diode D11 anode. Thanks for the tips and ideas.
greetings /Mathias Sweden Gothenburg
 
I was gonna have you meter the Fuse next, in and out of the holder (continuity and power on voltages). The board will flex a little, but not as bad as a 1010. In other words don't drop it on a table, shelf or whatever. The bottom will flex, contact the P.S. board and fracture it, rendering the unit into a 40-55lb doorstop until you fix it. No getting around the flex other to be gentle with it when moving
 
The circuit board AWR-056 is so bad that i make a new one, it is no idea to fix the old one.I can give a tip that it is really great to create, copy layouts to circuit boards in Photoshop :). What you see in the pictures is a ready layout for AWR-052 (56).
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Yes, then the AWR-056 circuit board is finished with new components. The only confusion was that it says 820 ohms on the R11 in the service manual and there was 1.3 kohm on the circuit board.

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Usually go by what's on the board. But, put it back in with the 1.3k and test your voltages. If low on that output(I'm on road and don't have access to schematic), then try the 820. Use whichever gives you closest voltages to bogey values.
 
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