Hey folks,
Weird problem with this rotel. It originally had a problem where it would briefly spin backwards, and then show 'error'. I tracked the problem down to two transistors - T102 & T103 respectively. These are BC338 and BC328. I replaced them and now I have a different problem. It spins relentlessly, as soon as the unit is turned on! the motor spins at full speed backwards, and if i leave it on for long enough i start seeing smoke, though i can't figure out where from.
Anyone got any ideas? Thanks in advance.
Weird problem with this rotel. It originally had a problem where it would briefly spin backwards, and then show 'error'. I tracked the problem down to two transistors - T102 & T103 respectively. These are BC338 and BC328. I replaced them and now I have a different problem. It spins relentlessly, as soon as the unit is turned on! the motor spins at full speed backwards, and if i leave it on for long enough i start seeing smoke, though i can't figure out where from.
Anyone got any ideas? Thanks in advance.
Just checking. Did you get exact matches ? Are the terminals in correct order ?
I ask because I used an equivalent that had different terminal order.
I ask because I used an equivalent that had different terminal order.
The "spinning backwards" is a fault of the reading system, and I doubt that those transistors are the issue, but what is driving them would be of more concern.
They are likely "digital transistors", and you should test them appropriately, not as a standard transistor would be checked.
The average CD player uses a complex system of checks in order to read and play, something that if you're not familier with, you'll be forever putzing with.
Best to start with focusing on the error code displayed, then go from there.
They are likely "digital transistors", and you should test them appropriately, not as a standard transistor would be checked.
The average CD player uses a complex system of checks in order to read and play, something that if you're not familier with, you'll be forever putzing with.
Best to start with focusing on the error code displayed, then go from there.
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There's no error code displayed, it just says 'error'. The fault only started happening after i replaced those transistors though, and they were DEFINITELY fried before i replaced them. It makes me think that whatever is making the cd spin backwards at full speed fried the original transistors?
The flowcharts in the service manual for Philips CD 482 on hifiengine have also been helpful to me.
The Rotel service manual there and tech notes also contains plenty of troubleshooting information.
Check the 4MHz ceramic resonator X102. They fail quite often... U109 must have the oscillator working properly for its CPU to work, i.e. U109 pin 38 and pin 39 should have a 4MHz sinewave signal present.
... and before you say "what the hell...I do not see any relationship" or something similar along those lines, the U109 needs a good working ceramic oscillator to derive an analog reference signal for the spindle motor - pin 35.