Bottlehead Forum
Bottlehead Kits => Mainline => Topic started by: mlineHK on March 24, 2022, 05:36:12 AM
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just completed all the terminal checks and all readings are good according to the manual. once I plug in the power cord to the extension cord with the switch of the socket switched off the wall socket fuse jumped. all visuals soldering are solid and I wired the transformer at 219-225v configuration after measurement. anyone can help?
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How did your power supply test go? (Page 52)
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says 223v
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o damn it, I skipped that test.
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is there a way to redo the test properly now?
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disconnecting 275 2 reds and 1 black , also disconnect 6.3v 1red and 1 black, should be able to redo the power supply test ?
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same thing, once plugged in the wall socket fuse jumps. at page 51 step.
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just disconnected the entire pt11 board out and try again the voltage test. same thing the wall socket fuse jumped.
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just found out only if te switch is flipped to power side the wall socket fuse won't jump. I have changed cable and rebuild the switch cable and what can be wrong ? can u check the photos? thanks very much.
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You have a dead short to ground at the 3 position terminal strip at the power transformer. re read those steps and correct that.
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Tks so much good catch. I will redo it today. I have used the wrong 3 terminal plate instead of the 5 cut to 3.
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tks for the time and input to answer. all good now except the kreg A side reading is 1v instead of 10-12v. b side is fine at 10v. any though?
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IA, Breg, and OB are all OK on both sides but you have 1V at KregB? Those results are not probable.
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Yes I have check twice. But I shall do it again tmr and post photo of each reading.
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It's incredibly unlikely to have 1V at a Kreg terminal and both Breg terminals reading correctly.
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Here are the readings.
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Can you just type them up into a nice list? It looks like you have at least one Breg that's 300V.
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Working fine tho. Tks.
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It's not a good idea to use an amp that doesn't pass its voltage checks. This can damage your amplifier and/or headphones.
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IA Side A [275v] 304v
IA Side B [275v] 306v
+275v DC [275v] 306v
+6.3vDC [55-65v] 59v
-6.3vDC [55-65v] 53v
BregA [220v] 304v/ Breg B [220v] 303v
-reg A [0v] 0v / reg B [0v] 0v
Kreg A [8-12v] 1.32v / Kreg B [8-12v] 1.29v
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thanks paul for having patience with me. here u go and hope we can find out and correct the problems.
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Neither of your high voltage regulators are working appropriately. Are you able to set the bias voltage for each 6C45P as directed in the manual?
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yes i was able to set both the bias to 145v.
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What are OA and OB on the center PC board?
The 1V at Kreg and 300V at Breg means the 12AU7 in the middle is sucking down nearly limitless current. The simplest way for this to happen would be a wiring error on the high current C4S boards.
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i am not sure what u mean by the OA ＆ OB on the center pc board. the OA connection of the center pc board is a white wire connected to C1. the OB is connected to A6 if thats what u mean .
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OA 1.6V / OB 1.9v on the center pc board.
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Can you unscrew each of the big C4S boards and post a photo of the bottoms of those boards?
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Here.
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I would add some solder and a lot more heat to all the solder joints on those boards except the ones where LEDs connect.
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ok thanks let me try that first and retest the V.
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hi Paul,
these r the results after re-solder every contact on all 3 boards.
IA A and B 274v
6.3 57v
-6.3 52v
275 275v
Biasing 1.45v
Breg A 273v
Breg B 216v
Kreg A 1.18v
Kreg B 10.66v
OA 1.76v
OB 2.02v
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Resoldering your connections brought one side into proper operation. I would suggest that you also resolder the center PC board and perhaps that will fix the other side.
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That's what I thot and I have done re soldering the middle board as well. I will redo again and see.
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You could also replace the 431 regulator on the side with the very low Kreg voltage.
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Thank you Paul will try to replace them.
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Thank you Paul will try to replace them.
It, you definitely don't want/need to replace the working one.
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Yes will replace the a side one.
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hi Paul,
after replacing the A side LM431ACZ , the results remain unchanged. what do u suggest I shall do next?
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Have you reflowed all of the solder joints in the amp?
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All joints on 3 boards only.
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I would go over the 12AU7 socket and associated terminal strips as well.
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ok will do thanks.