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Does anyone know if the power tubes filament in this amp are in series? Not lighting up and I dont see 6.3volts anywhere on the PT output. Thanks in advance.
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The output tubes are in parallel.
The schematic can be found here: http://forum.highlyliquid.com/attach...5&d=1319883369 -
Thank you so much, a great help!Comment
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Look for the 6v wires from the power transformer. Chances are good that somewhere between them and the power tubes, a contact is burnt. Look first at the ribbon from the main board to the power tube board.Education is what you're left with after you have forgotten what you have learned.Comment
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Enzo, that ribbon connector you speak of looks to be hard soldered on both ends, guess I should pull main board and check solder connections on the underside? Funny thing, only place I come close to reading 6 volts is at the pilot lamp. Further probing is probably in order.Comment
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That was just one possibility. The 6v comes onto the main board, through a fuse, then through the ribbon to the power tube board.
There was a 5-pin connector on the wires from the power transformer to the main board. The two yellow wires on one end should be the 6v. Measure the AC voltage between them, NOT to ground. Did you check the fuse? You MUST pull the fuse from its clip and test it with a meter, you cannot measure the fuse resistance in its clip. That 5-wire connector is supposed to be cut off and the wires soldered to the pins. After a certain point they did it at the factiry, but any amp that the connector is still there, should be rewired that way.
So if you have 6v between the yellow wires, follow it across to the power tube board. SOmewhere there will be an interruption.Education is what you're left with after you have forgotten what you have learned.Comment
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Sure enough Enzo, got 6 volts between the 2 yellow on the 5 pin but not across 2 and 7 on the power tubes. That connector shows no external signs of burning, but once I got it off the second yellow (from the end) is blackened internally. I checked continuity between those 2 pins (connector off) and 2 and 7 on the tubes and connectivity was established. Tomorrow I will solder those leads directly to the main board, this will probably resolve the issue. Will update once complete. Thank you for your insight!Comment
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Bugera 333XL
Problem solved, soldered all the leads directly to the board after cutting off plastic connectors, Working great! Thank you all for your help!Comment
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