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Seeking schematic for Rotel RB-890 power amplifier
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<blockquote data-quote="Shonver" data-source="post: 58773" data-attributes="member: 34"><p>Aah! Ludo! Thanks! You're a real treasure!</p><p></p><p>I just bought one. I opened it and found a modification that turned out to be a speaker turn-on delay of sorts. Big relay. Puts a 10R resistor in series with the speaker, then shorts it (10R resistor) out after a short delay. Delay is just an RC network feeding the relay coil. Curious. I then discovered the need for the delay. One of the channels has 150mV DC offset. I removed that board and saw that it had been repaired, complete with customary lifted tracks and bad soldering. The whole board is coverd with old flux; I've just finished cleaning it off with thinners. Hoping that will sort out the offset issue, else will have to find the offending transistor(s).</p><p></p><p>The power transistor insulators are the grey silicon impregnated type. I found that two of these are actually just normal plastic film of the same colour!</p></blockquote><p></p>
[QUOTE="Shonver, post: 58773, member: 34"] Aah! Ludo! Thanks! You're a real treasure! I just bought one. I opened it and found a modification that turned out to be a speaker turn-on delay of sorts. Big relay. Puts a 10R resistor in series with the speaker, then shorts it (10R resistor) out after a short delay. Delay is just an RC network feeding the relay coil. Curious. I then discovered the need for the delay. One of the channels has 150mV DC offset. I removed that board and saw that it had been repaired, complete with customary lifted tracks and bad soldering. The whole board is coverd with old flux; I've just finished cleaning it off with thinners. Hoping that will sort out the offset issue, else will have to find the offending transistor(s). The power transistor insulators are the grey silicon impregnated type. I found that two of these are actually just normal plastic film of the same colour! [/QUOTE]
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Seeking schematic for Rotel RB-890 power amplifier
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