hudd
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Post by hudd on Mar 20, 2016 8:14:32 GMT -7
My Ghia is blowing fuses left and right. It was working great one day then it blew a fuse. I put 2 new 12ax7s in it, still blows fuses instantly. I put 2 new EL84s, same issue.
When I put the EL84s in it turned on but no sound would come out. It stayed on and didn't blow the fuse but when I turned it off and tried to turn it back on it blew the fuse again.
Now I'm thinking it's the rectifier tube or output transforme. Or maybe I'm way off, the app is junk and I need to replace it with a Zwreck.
If it's the rectifier tube do I need to replace just the tube or the tube and the rectifier? Any other ideas?
I have been borrowing a friends Jackson Brian 30 to use while my app is down but I miss my Ghia!!!!
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Post by headshrinker (Marc) on Mar 20, 2016 9:02:02 GMT -7
The tube is the rectifier. You just need to replace it. Make sure your connections to the speaker are good and not shorting out. If it's a head/cab arrangement try another cable. Make sure it's not a guitar cable, but a speaker cable. Another possibility is that the on/off switch has gone bad and it's intermittently shorting out and blowing the fuses. If you originally had a bad EL84, when it went, it could have taken out a resister with it. That's not uncommon. After that it will keep blowing fuses until it is replaced.
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Post by Jaguarguy (Mike) on Mar 20, 2016 9:22:55 GMT -7
What Marc said - My guess is it is the rectifier tube.
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hudd
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Post by hudd on Mar 20, 2016 9:53:43 GMT -7
If you originally had a bad EL84, when it went, it could have taken out a resister with it. That's not uncommon. After that it will keep blowing fuses until it is replaced. My Ghia is a head so I an positive that it is not a cable or speaker. I took the Ghia out of the chain and out the Jackson in its place and everything worked as it should. I'm going to order a new rectifier tube today. Any suggestions on a good one? Where is the resister located that may need replaced? Thank you for the help. This thing has been driving me nuts for a month. |
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Post by headshrinker (Marc) on Mar 20, 2016 10:08:33 GMT -7
Usually it takes out a resister that is on the tube socket for the EL84. Screen resister? Usually you can see that it is burnt with some blackish color on it. If you are not comfortable going into the insides of a tube amp, have someone who knows what they are doing look it over. Don't touch anything that you don't know what it does. The voltages that are stored in some of the caps can actually kill you, even with the amp off. If you can find NOS rectifier they are worth the extra money, as they will usually outlive a current production one by a very long time. As for current production ones, I have found, they are all pretty much a crap shoot. Lots of folks use the JJs.
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Post by Jaguarguy (Mike) on Mar 20, 2016 10:16:22 GMT -7
Here's a,good,read on rectifiers in general. www.guitaramplifierblueprinting.com/rectifiers.htmlI agree with Marc that NOS are the way to go. I like JAN or RCA labelled tubes. Though they can be twice the price of new tubes they will usually outlast the amp. New,tubes are a crap shoot. Check,with Tube Depot, Doug's Tubes or another trusted retailer to see what they have on hand. Should be able to pick a NOS in the $30 price range. |
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Post by LT on Mar 20, 2016 16:29:08 GMT -7
+1 on the rectifier. Totally fixed my Ghia's fuse issues. The amp is NOT junk....but I do recommend adding a Wreck!
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hudd
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Posts: 21
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Post by hudd on Mar 25, 2016 13:44:23 GMT -7
OK I'm getting frustrated now. I have replace every tube in the amp and I'm still blowing fuses. Also before the fuse blows no sound comes out. Any ideas.
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Post by Jaguarguy (Mike) on Mar 25, 2016 13:55:11 GMT -7
Did you follow the Doc's troubleshooting process? Sometimes you can get a new tube that is bad so if you change them all at the same time you'll never know.
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Post by John on Mar 25, 2016 14:41:41 GMT -7
OK I'm getting frustrated now. I have replace every tube in the amp and I'm still blowing fuses. Also before the fuse blows no sound comes out. Any ideas. if that's the case, I see a few possible things happening. 1) When the old rec tube went bad, it burnt other things with it on it's way out. (see resistor conversation from above..and possibly more than just the screen resistor.) You may not be able to see it. It may require a tech to figure it out. 2) New rec tube may be bad. 3) Are you using the correct fuses? slow blow? My money's on 1 or 3. Keep us posted. |
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hudd
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Posts: 21
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Post by hudd on Mar 25, 2016 14:54:40 GMT -7
Just followed the guide and apparently it's the power transformer. Any one have any idea on what that cost to replace?
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Post by KeithA on Mar 25, 2016 15:22:58 GMT -7
Just followed the guide and apparently it's the power transformer. Any one have any idea on what that cost to replace? I would call the Z shop and send it in for a once over......... |
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Post by John on Mar 25, 2016 15:26:12 GMT -7
Just followed the guide and apparently it's the power transformer. Any one have any idea on what that cost to replace? I just re-read the troubleshooting procedures from the Z website. I don't see how you deduced it was the power transformer? Granted, if you pass #1's test, it says it's NOT your power transformer. But the other tests don't say it IS your power transformer. The others don't mention the transformer at all. The Doc's transformers are known to be over engineered. There's a forum member here who's young son turned on his Ghia without a speaker connected. (VERY bad...known to cook some transformers) The amp remained on for THREE days before it was noticed. The guy plugged in a speaker...the amp worked fine. I've been on this forum for about 10 years. (OMG has it been that long?) I've read stories about all sorts of amp problems. 99% of the time, it's a tube problem. I don't recall EVER hearing about a transformer malfunctioning. The remaining 1% is usually another component that gets taken out when a tube blows. (which is one of the things I said could be happening to your amp) I'm not saying it ISN'T the power transformer, only that it's VERY likely it's something else. Did you buy the amp new? It could still be on warranty. Doctor Z himself cruises this forum. Perhaps he'll see this. He has a very good reputation for helping and making things right. If you don't have (or trust) a local tech, you can ship the amp back to the Z shop and they'll fix it up like new. (if it's not warranty work, you'll pay for this service...but you KNOW you're amp will come back in top shape.) |
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hudd
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Post by hudd on Mar 25, 2016 17:01:13 GMT -7
The reason I am assuming it's the PT is it did not pass test number 1. I took all the tubes out of the amp, Put a new fuse in, and turned it on. The amp light up like it should, I shut it off and turned it back on and the fuse blew.
Now that I think about it , maybe the it's not the PT. If it was definitely a bad PT then the fuse should have blew the first time it was on. Right?
I did pull the internals out of the head and I couldn't see any capacitors that were obviously blown. Every thing looked good.
I bought the amp used. It's a 2007 model.
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Post by Jaguarguy (Mike) on Mar 25, 2016 17:26:34 GMT -7
Here is a link to Don DePew (repair man extraordinare) at Dr. Z. I'm sure he can help you try to diagnose the problem.
repairs@drzamps.com
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hudd
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Posts: 21
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Post by hudd on Mar 25, 2016 18:25:00 GMT -7
Thanks. I just emailed him.
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hudd
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Posts: 21
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Post by hudd on Mar 29, 2016 17:56:06 GMT -7
Just an update for any one interested or any one having a similar problem in the future that might stumble soon this forum.
I have been emailing back and forth with Don from Dr z for the past few days. My amp is going back to them for repair. They are not sure exactly what the problem is yet. We tried diagnosing using the trouble shooting guns and it failed test one. I really hope it's not the pt. I will update this thread when I find out what it is.
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Post by Jaguarguy (Mike) on Mar 29, 2016 18:19:49 GMT -7
I've taken several amps to Don to fix - they come back as good as new. He's a great guy and extremely good at what he does.
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hudd
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Posts: 21
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Post by hudd on Mar 29, 2016 19:55:58 GMT -7
I'm sure it will come back as good as new.
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