My amp won't come off standby... please help.

[taper420]

Hi everyone,
I'm new, but hopefully you guys help out the noobs around here.

last week my amp blew a tube. at least that's what I thought. there are two lights, one for the standby and one for the power... the power one stayed on... the standby light went out (which is what happens when you put it on standby). I checked the back and sure enough, one of the tubes was out. I just got a matched quad and put them in. I put it on standby to warm em up... after about 10 minutes I switched the standby switch to on... but no green light. All the tubes are lit up in the back. It's not the fuse, because I took that out and nothing lit up, whereas with it in, it acts as if it's on standby (tubes light up, channel lights, pedal switch). So what are my possible culprits? I'm still under warranty... so if I can't figure this out tonight it's going into the shop.

amp: peavey 6505+, stock tubes we're Sovtek 6L6GC's, were replaced with Sovtek 6L6WXT+'s

[martin manning]

Might be a high-tension fuse inside the chassis that got taken out with the tube. No schematic on the web that I could find easily... do you have one?

MPM

[taper420]

there's a block diagram at the bottom of the manual
http://www.peavey.com/assets//litera...s/00575680.pdf

as far as a schematic, no I don't have one. I'll see what I can dig up.

but if it was a fuse going to one of the tubes, wouldn't that tube not power up now? They all power up just fine, but the won't switch off standby.

[taper420]

okay...this is not my amp but it's close, so maybe the relevant circuitry is the same:
http://www.schematicheaven.com/newam...ey_evh5150.pdf


i have a 6505+ which is exactly the same as a 5150 II
that schematic is for a 5150
The original 5150's (and 6505's) have one less preamp tube (than the 5150 II, and 6505+), and they don't have separate EQ for the channels... that's the only differences I'm aware of

[martin manning]

The heater circuit may be fused too, but it is evidently working. I'm referring to the high voltage supplying the tube plates, and it is not uncommon to have a fuse on that to protect the transformers if a tube shorts.

Usually these are inside to keep consumers from replacing them incorrectly or without determining what caused them to blow, which could cause more damage.

Standard cautionary statement: there can be high voltage in there even if the amp is off and unplugged. Take it to a tech if you are not familiar with the proper safety precautions.

MPM

The power supply is not shown in that schematic, so no help there. Maybe someone else on the forum will know.

[taper420]

yup, that's what I'm planning on
there's no way I'm taking this thing apart, especially when it's still under warranty

[martin manning]

Good plan!

[Enzo]

No doubt your internal high voltage fuse is blown. Usually the reason for that fuse blowing is a bad power tube. You can replace the bad power tubes, but the fuse itself won't heal, it must be replaced.

You will not void your warranty opening the amp up. Fuses are in clips so they can be changed, and you can't do that without opening up the amp. I am an authorized Peavey repair center - among others - so trust me. There are not secret seals to break or anything. No one cares if you looked inside your amp. What voids warranties is doing work to the insides - like changing resistors or soldering something.

Always work with the amp unplugged and power off for at least 10 minutes, the vovltages the amp runs on inside can KILL YOU.

Also, the warranty covers the amp for 5 years, but the tubes are only covered 90 days. SO taking an amp in for warranty service, it will not be a warranty repair if the trouble is tubes. Not after the 90 days anyway.

And even further, most companies don't warrant fuses AT ALL. So if you have fresh tubes in there, and the amp doesn;t work because the inner fuse is blown, that is not something that the warranty covers. You'd be paying the service shop to change the fuse.

[Danglin' Fury]

If it's not the fuse, you should check the 400 ohm 10 watt resistor that is in series with the standby switch. I had a 5150 that had this burned open. If it reads more than 400 ohms, it's bad. My $.02

[taper420]

okay, so....
how do you discharge capacitors?
and how can I find out what fuse I'll need before I take it apart?
maybe this can help: http://www.schematicheaven.com/newam...ey_evh5150.pdf

and if I bring it in with 4 working tubes... how will they know a bad tube blew the fuse?
and are you absolutely positive a non-user serviceable fuse is not covered under warranty? That's a pretty crappy deal.

[Enzo]

yes, it also could be that 400 ohm resistor - and that WOULD be a warranty repair.

Look on the warranty card that came with the amp or look up their stated warranty on their web site. Tubes fail all the time, and most makers waranty them for like 90 days more or less as a courtesy. SOme tube sellers warrant tubes for 6 months, consider that when buying replacements. Fuses and light bulbs are usually excluded from warranty simple because they are easily blown. Some momentary power line glitch and a fuse blows. it did its job, protected you and the amp, nothing harmed, new fuse and on you go. Is that a defect in parts or workmanship?

Here is something many consumers are confused by, they think a warranty is insurance. It is not. A warranty says a company promises - warrants - that their product will work when you get it, and will continue to work, and if any defect in the workmanship causes it not to work, the company will make it right. When a fuse blows, that is not a defect in workmanship. Likewise, many people are genuinely surprised when I tell them the warranty does not cover them breaking off half the controls on the front panel. When the PA speaker fell on the amp, that is not a factory defect.

You have a 6505+ which is a 5150-II. Schematic Heaven has the correct 5150-II drawings, so look them up instead of the ones linked above for the older model.

The high voltage fuse is F1, and is a 2 amp fast blow. Inside the amp you will see a row of 5 fuses, and F1 is the one closest to the front control panel.

use the search feature of this web site for discharging caps, we have discussed it numerous times.

If you brought it in with a new set of working tubes, and the fuse us blown, they will probably recognize that the tubes are new, so it won't be a mystery that old tubes were removed. They would replace the fuse and test the amp to see that it was working properly. And besides ther is no reason to not tell them the tubes are new anyway.

[taper420]

so looks like I have some work to do.
here's the official response from repair@peavey.com:

Sounds like you had a power tube failure and that took out F1
just because a tube is new does not mean it's good.
You can check F1 yourself, just be sure the unit is unplugged from the wall
socket first.
F1 is a 2 amp 250 volt fuse.
thanks
gene

and here was my letter to them:

amp: peavey 6505+, stock tubes we're Sovtek 6L6GC's, were replaced with Sovtek 6L6WXT+'s (after the problem)

last week my amp blew a tube. at least that's what I thought. The amp kinda just fizzled out, the standby light went out, I checked the back and sure enough, one of the tubes was out. I just got a matched quad and put them in. I put it on standby to warm em up... after about 10 minutes I switched the standby switch to on... but no green light. All the tubes are lit up in the back. It's not the fuse, because I took that out and nothing lit up, whereas with it in, it acts as if it's on standby (tubes light up, channel lights, pedal switch).

My amp was bought around Christmas of last year, so it is still under warranty. The tubes are not. But I have replaced them and they are brand new. My research has pointed to a likely culprit: the internal F1 high voltage fuse has blown. Now here's my question..... if that actually is the problem... is a non-user serviceable fuse covered under warranty? I really don't want to get killed taking apart my amp to change a fuse... but I also don't want to pay for a service center to merely change a fuse for me... especially when the thing is less than a year old and should be covered.

Please advice me on my next course of action.... thank you.

so no mention from them on discharging capacitors, using one hand, safety goggles, or any safety precautions. just unplug it and go ahead and do it. strange. my initial though is he thought I was talking about the f5 fuse which is accessible from the back. but i think i made it clear that it wasn't that fuse in my email.

[tubeswell]

Unplug the power tubes and take them to someone with a tube tester to find out if any of them are bad. Most likely one or more of them could be. However if none of them turn out to be bad, then take the amp to a Peavey service tech, and demand it be fixed under warranty (if it is still under warranty). If it is not under warranty, take it to any good tech and ask them nicely how soon they will be able to do it. I'd keep $100 handy.