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Post by Pete aka shouldb on Apr 26, 2016 8:27:43 GMT -7
Hi guys,
Plugged in my Z28 at a gig last Sat, and there was zero sound coming out of it - not even a hum.
Checked out all leads (mains, speaker, instrument) and all were fine, and swapped them all with leads which were working at that time on my Therapy.....still nothing.
Swapped out the 1Amp slow blow (which hadn't blown, but swapped it anyway - and tested both the old and new fuses with a meter) and still nothing.
Looked inside, and all tubes glowing nominally with no smoke, smell, fizz or crackle anywhere - all was looking totally normal.....as were all the components I could see (nothing looked burnt or blown out)
......still no sound.......
Any thoughts ??
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Post by benttop (Steve) on Apr 26, 2016 8:42:51 GMT -7
If the rectifier gave up it will behave that way. Sometimes they don't short out - they just quit entirely. With no power, the tubes will all still glow because they are getting heater voltage from the mains transformer, but no B+ to run the amplifier; glowing tubes and no sound.
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Post by BritInvasion on Apr 26, 2016 8:44:06 GMT -7
If the rectifier gave up it will behave that way. Sometimes they don't short out - they just quit entirely. With no power, the tubes will all still glow because they are getting heater voltage from the mains transformer, but no B+ to run the amplifier; glowing tubes and no sound. ^^ This
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Post by Jaguarguy (Mike) on Apr 26, 2016 9:52:29 GMT -7
I agree with Steve and Frank - probably rectifier. It's happened to me a couple of times.
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Post by thatstatuemoved on Apr 26, 2016 17:41:07 GMT -7
I would bet on the recifier.
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Post by Pete aka shouldb on Apr 28, 2016 1:45:41 GMT -7
And THATS why I love this place! Will replace the rectified and see what happens Thanks chaps
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Post by Pete aka shouldb on Apr 28, 2016 1:47:31 GMT -7
If I may.......talk to me about SS rectifiers. I know a couple of the Docs amp have them. I assume they don t blow?
Pros and Cons?
Are there like for like SS rectifier replacements? Do they alter the tone much?
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Post by strat59 on Apr 28, 2016 3:36:07 GMT -7
I always carry a ss rectifier as a back up for my Maz 38's tube rectifier. It plugs in just like a tube. I don't like the feel as much but it will get you back online quick.
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Post by benttop (Steve) on Apr 28, 2016 5:21:21 GMT -7
The SS rectifiers are more reliable, but be careful about using the plug-in variety, as they can provide a bit higher voltage which may be ok or maybe not. I believe I've read here that the Doc says they are ok on a 4xEL84 amp, but not on a 2xEL84, so fine on the Maz Senior but not the Junior. I don't know what he has to say about the Z-28 though.
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Post by Pete aka shouldb on Apr 28, 2016 6:50:38 GMT -7
Okay, issue solved....it was the Rec tube indeed! Thanks Steve et al.......new Sovtek ones ordered up
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Post by Jaguarguy (Mike) on Apr 28, 2016 9:18:53 GMT -7
What a great place! Who needs a tech to sus out a problem when you got the Z-bros (and Z-sisters) waiting to help out!
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Post by zpilot on Apr 29, 2016 5:49:54 GMT -7
A lot of what a tech (myself included) does when troubleshooting is guided by past experiences. You get the benefit of a fair amount of experience here on this forum.
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