Here are some fixes for these:
Problem with HF or no HF output- replace U31 TDA 7294
No audio at all- check resistors R243,248, 288 (upper board by SMPS).
Audio not as loud as it should be, Audio weak at mic level or not much change in level from 4db to mic position/+40db max-
Open R22 (smd resistor 10 ohms)
Audio cuts out- check for a glob of yellow brown glue (similar to what mitsubishi used to use) near R3, R7, R8, R11, C6, C7 and U3. Cable from the XLR board is often glued and that glue covers a few smd resistors and small smd caps. The glue tends to break off (vibration/transport) taking one or more smd parts with them. This one will often make you decide to replace the entire board assy because you threw it across the room.
No LF drive at all- replace U28, Q11, Q12, D19 adn D23. Also check R156 and R157 for opens.
Intermittently won't turn on or won't power completely or has hiss sound then dies when powering up-
C189- 192 may be dry/open. Check those with an ESR meter if you have one, or just replace them.
C189,190- 680uf@200v ; C191,192- 220uf@200v
Problem with HF or no HF output- replace U31 TDA 7294
No audio at all- check resistors R243,248, 288 (upper board by SMPS).
Audio not as loud as it should be, Audio weak at mic level or not much change in level from 4db to mic position/+40db max-
Open R22 (smd resistor 10 ohms)
Audio cuts out- check for a glob of yellow brown glue (similar to what mitsubishi used to use) near R3, R7, R8, R11, C6, C7 and U3. Cable from the XLR board is often glued and that glue covers a few smd resistors and small smd caps. The glue tends to break off (vibration/transport) taking one or more smd parts with them. This one will often make you decide to replace the entire board assy because you threw it across the room.
No LF drive at all- replace U28, Q11, Q12, D19 adn D23. Also check R156 and R157 for opens.
Intermittently won't turn on or won't power completely or has hiss sound then dies when powering up-
C189- 192 may be dry/open. Check those with an ESR meter if you have one, or just replace them.
C189,190- 680uf@200v ; C191,192- 220uf@200v
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