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Help with replacing bias output resistor for cassette recorder
Help with replacing bias output resistor for cassette recorder
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Old 15th March 2015, 06:10 AM   #1
ferrochrome is offline ferrochrome  New Zealand
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Default Help with replacing bias output resistor for cassette recorder

Hi all,
I have a Sharp CD-C2400 that as of now produces very tinny recordings on normal bias cassettes, I'm suspecting that there is a drop in bias current and am now trying to identify which components to inspect on. Also, can the bias output resistor be identified? I'm trying to use a variable resistor instead of a fixed one so that I can control the bias manually.

Attached is the schematic of the C2400's tape deck.
Thanks in advance,

ferrochrome
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File Type: jpg cdc2400tape.jpg (207.5 KB, 31 views)
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Old 15th March 2015, 10:36 AM   #2
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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Both decks playback pre recorded OK?
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Old 15th March 2015, 10:37 AM   #3
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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Tape mute switches OK?
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Old 15th March 2015, 10:46 AM   #4
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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There is no Bias Output resistor as such. It will be a switch contact or mute transistor control I expect. The chip either works or doesn't.
Keep an open mind and be methodical, don't go in too deep, then you will fix it.
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Old 16th March 2015, 05:00 AM   #5
ferrochrome is offline ferrochrome  New Zealand
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Hi JonSnell Electronic,

the deck seems to be playing its own tape recordings that were made a half year ago properly, there are muting transistors. Does it seem possible to add bias control to the circuitry?
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