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Post by steamroller on Mar 7, 2021 22:56:39 GMT -7
I am having a ball with my my new Z-Plus. I have also learned a few things about guitar amps along the way. I have a problem I have been researching for two days now, I'm not sure what my next check should be- let me run it by you.
1. I power up my Z-Plus amp, I let it warm up for 1-2 minutes, flip the standby and then my baby gives me a ROAR! For only 1/2 of a second! The roar is like the alien communication tone on "Close Encounters of a Third Kind" prior to the quaint little melody. And then everything is fine. I commence playing my guitar.
2. The volume is turned to off, on startup, but the volume for the roar is coming from somewhere.
3. The power tubes are showing a 1/8" - 1/4" section of red plate, about 2/3 of the way up on the same plate of each 6v6 tube.
4. Tapped all the tubes to listen for odd sounds,microphonics they all sounded normal and very uniform.
5. So far, the amp does this only from after an overnight cold startup. After the initial blasting, you can play to your heart's content and everything is fine. Shut the amp down 1-2 hrs. later and an additional startup will be normal.
Any help is appreciated.
-steamroller-
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Post by purpletele on Mar 8, 2021 9:01:02 GMT -7
Steamroller,
That is a symptom that I have never heard mentioned.
I would think it is a rouge tube acting up.
I am anxious to see other responses.
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Post by zpilot on Mar 8, 2021 9:13:52 GMT -7
First I suspect what you are seeing in the power tubes is not redplating but actually just the heater filaments glowing. Take a really close look at them. If they really are redplating then you need to have a tech look at it before you do anything else.
As for the roar, my first thought would be it is related to the filter caps charging. Especially since it only reoccurs after a couple of hours, which would indicate that they have discharged. Again, that would be time to see a tech. I don't have a schematic so I can't tell you where the Standby Switch is in the circuit or whether the filter caps have a bleeder resistor. A tech would be able to see that with a quick look.
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Post by daddyelmis (Greg) on Mar 8, 2021 9:16:36 GMT -7
Is this a new Z-Plus or new-to-you Z-Plus, and if the latter do you know how old the power tubes are?
Given the symptoms I’d guess power tubes or rectifier, but probably power tubes. Swap them out with a new or known good set - that would be the fastest way to find out.
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Post by steamroller on Mar 8, 2021 10:00:53 GMT -7
daddyelmis, I am the first owner, the amplifier was built 2/2000, I purchased it new from Sweetwater 7/2000. I play this amp every day for approximately 2hrs. About a month ago I replaced the rectifier, and all was well. I would say I have 500hrs. of playtime on this amplifier.
-steamroller-
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Post by Jaguarguy (Mike) on Mar 8, 2021 10:26:40 GMT -7
Has it been like this since day one or did it crop up after a while. Did it happen after you replaced the rectifier or was it that way before?
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Post by steamroller on Mar 8, 2021 13:36:21 GMT -7
Mike, this condition is new, maybe in the last 4-5 days, approximately one month after I replaced my rectifier. I played my amp every day since the rectifier replacement (Shuguang 5AR4 ), and the amp operated normally and sounded great, until this new situation.
-steamroller-
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Post by headshrinker (Marc) on Mar 8, 2021 15:19:40 GMT -7
If you still have it and if it worked when you took it out, I would put the old rectifier back in and see what happens. 500 hours in a class A amp, even with 6V6s is a lot of hours, I would try some new power tubes as well, especially if you don't have a spare set. You're going to need them sooner or later.
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Post by Jaguarguy (Mike) on Mar 8, 2021 16:16:01 GMT -7
Marc has some good ideas. Also, here is a good trouble shooting video from Doc - worth watching even if you don't want to try to resolve on your own. drzamps.com/info/faq-troubleshoot/
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Post by steamroller on Mar 8, 2021 16:35:18 GMT -7
Marc / Mike, I tried the old rectifier and it just blew the fuse just like the old tube did previously. I am going to order another set of power tubes. I will follow the video troubleshooting recommendations. I have a feeling my problem is going to be my power tubes. They just haven't blown a fuse yet. I wish my amp was just buzzing or humming or giving off a definitive power tube failure symptom. Anyway when this is resolved I will post the outcome in this thread, unless a better location is recommended. Probably be a week or so to get tubes.
-steamroller-
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Post by zpilot on Mar 8, 2021 23:06:58 GMT -7
I'm confused about the build date. 2/2000? That model has only been made for around 3 years or so.
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Post by steamroller on Mar 9, 2021 1:05:21 GMT -7
Sorry about that, 2/2020
-steamroller-
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Post by zpilot on Mar 13, 2021 2:19:04 GMT -7
Any progress on this?
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Post by steamroller on Mar 13, 2021 10:33:48 GMT -7
zpilot, thanks for inquiring. I have ordered two matched JJ6v6 tubes and they're supposed to be here today! If all goes well my amp should be up and running. Whatever the outcome is, I will post in this thread. I have kept searching every post and thread I can find, and so far, no one has described the exact symptom my amp has. I have not experimented too much, to determine if different adjustments on my am would cause a change in the tone, or elimination of the tone. Just afraid to mess up my amp! Just so you know, I am not put off by this situation at all! I understand that amps. need to be maintained. I am fortunate to have all the help provided by ztalk members in solving my problem. Though I have only one electric guitar, and "only" my Z-Plus, my fall back is my 0003 Collings-not so bad!
-steamroller-
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Post by steamroller on Mar 15, 2021 13:57:29 GMT -7
Still waiting for my tube shipment. Post Office sent my package to the wrong city! I hope it makes it my way sometime soon.
-steamroller-
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Post by premiumplus (Dave) on Mar 15, 2021 16:46:07 GMT -7
Gotta love the USPS performance the last few years...I had a shipment from 300 miles away get sent clear across the country, then back to Kansas City where it languished for a week, then back to Indiana and finally up to me in Michigan. Sheesh. No wonder they're always losing money!
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Post by steamroller on Mar 15, 2021 18:46:06 GMT -7
Now, you're scaring me!
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Post by zpilot on Mar 15, 2021 23:48:55 GMT -7
An item I ordered wound up in Puerto Rico.
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Post by nicholas on Mar 17, 2021 8:11:24 GMT -7
I power up my Z-Plus amp, I let it warm up for 1-2 minutes, flip the standby and then my baby gives me a ROAR! For only 1/2 of a second! The roar is like the alien communication tone on "Close Encounters of a Third Kind" prior to the quaint little melody. And then everything is fine- Lol. I had to google that noise. It's like an electric arc sound. Did you happen to look at the tubes when you hear the noise? I had that happen before and it was a bad power tube. I could see crazy stuff happening in the tube when it made the noise. Like bottled lightning. And like you said, the noise came out the speaker even with the amp volume off. It was crazy loud. Good luck with it. Hope your new tubes fix it.
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Post by Chilly Gibbons (Todd T.) on Mar 17, 2021 8:45:36 GMT -7
I power up my Z-Plus amp, I let it warm up for 1-2 minutes, flip the standby and then my baby gives me a ROAR! For only 1/2 of a second! The roar is like the alien communication tone on "Close Encounters of a Third Kind" prior to the quaint little melody. And then everything is fine- Lol. I had to google that noise. It's like an electric arc sound. Did you happen to look at the tubes when you hear the noise? I had that happen before and it was a bad power tube. I could see crazy stuff happening in the tube when it made the noise. Like bottled lightning. And like you said, the noise came out the speaker even with the amp volume off. It was crazy loud. Good luck with it. Hope your new tubes fix it. I've had that bottled lightning/fireworks thing in a bad EL84 as well. I could tap it and it would quit, something inside shorting that I could effect mechanically. Probably the same thing, but in your case the short is broken by what is happening inside the tube itself. As Nicholas mentioned, if you can identify the bad tube you can keep the other as a spare.
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Post by zpilot on Mar 17, 2021 11:03:47 GMT -7
The noise sounds like it could be a tube to me also but your description in item 5 indicates that it is related to a filter cap charging.
"5. So far, the amp does this only from after an overnight cold startup. After the initial blasting, you can play to your heart's content and everything is fine. Shut the amp down 1-2 hrs. later and an additional startup will be normal."
When charged it seems to work fine. It would take a while for the cap to discharge after turning the amp off. Try this. Fire the amp up (just an expression) and make sure it is working OK. Then switch it to Standby and let it sit for 15-30 seconds. Switch it off Standby and see if the noise happens again. If it does not that indicates to me that because the cap has remained charged (which would be normal) it is related to the initial charging.
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Post by steamroller on Mar 17, 2021 12:25:16 GMT -7
PROBLEM SOLVED!
My matched JJ6v6 tubes came in this morning. It was a plug and play deal! My Z-Plus is normal again! How sweet it is. Thank-you to everyone at z-talk, for your help. The power tubes were the culprit. It is amazing to me how much help I got to solve my problem. Just so you know, this forum is the only source I have for guitar amp troubleshooting. Not being part of the "electrified" scene until last year, leaves me in an ignorant state on the subject. I don't know of a local amp. technician, so I am on my own. But I am learning this stuff, bit by bit. Thank-you, Z-TALK members.
-steamroller-
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Post by steamroller on Mar 17, 2021 12:39:27 GMT -7
zpilot,
I never got a chance to try out your test, but it makes a lot of since. I had installed my tubes before I read your post. I have been kind of chicken to try too many tests on my amp. I know that the very limited information I provided, doesn't make easy to troubleshoot. Thanks! But man I hope my caps were not part of my problem!
-steamroller-
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Post by LT on Mar 17, 2021 13:33:22 GMT -7
Glad to have you on board here steamroller. There are indeed a lot of folks with a ton of knowledge here.
In addition, the Dr Z staff is excellent and provide great service. I personally wouldn't trust my Z's to a local tech unless they were authorized by Z.
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Post by nicholas on Mar 17, 2021 14:55:48 GMT -7
The noise sounds like it could be a tube to me also but your description in item 5 indicates that it is related to a filter cap charging. "5. So far, the amp does this only from after an overnight cold startup. After the initial blasting, you can play to your heart's content and everything is fine. Shut the amp down 1-2 hrs. later and an additional startup will be normal." When charged it seems to work fine. It would take a while for the cap to discharge after turning the amp off. Try this. Fire the amp up (just an expression) and make sure it is working OK. Then switch it to Standby and let it sit for 15-30 seconds. Switch it off Standby and see if the noise happens again. If it does not that indicates to me that because the cap has remained charged (which would be normal) it is related to the initial charging. Yeah, it's weird. I had a power tube do that before. The only thing I could assume is that when it got warm the metal in the tube structure expanded just enough to stop whatever was arcing inside. Even just enough heat from a slightly warm amp was enough to prevent the arc. But after an extended period of cool down, and all the warmth gone from the amp the tube internal structure contracted and something got too close would arc on start up. It's just a theory and could be wrong. But that's all I could rationalize when it happened to me. In my case it was a full amp volume arc sound even with the amp volume off. Extremely loud! So loud I dropped my guitar the first time it happened. Of all the years of tube amps and tube related problems, that's the only time I've ever had that happen. Thankfully!
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Post by purpletele on Mar 17, 2021 18:24:09 GMT -7
Even seasoned amp owners act like little puppies when their own amp starts acting up, I am included in that category.
My Z-Plus didn't like my JJ Rectifier and I couldn't figure it out. I brought it to Ben Fargen whose is a colleague, and he helped me off the cliff.
It had him going for a few hours as well. My expensive learning curve was that you need a nice NOS or Z Specified rectifier in the Z-Plus and Maz models.
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