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Jamie1281734176

Blues Custom 30 problems

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Hello all, I signed up to talk about my new BC30 and unfortunately the first post is going to be about problems. I got it used on craigslist and when I picked it up everything sounded good. When I took it home it wouldn't come on at all. Well, I took it too an amp tech (because yes, I'm a noob) and he said a tube was bad and the fuse was blown. A hundred dollars down the road everything seemed fine. I used it once to play at a church. Today, one week after getting fixed, I try to turn it on and again nothing is lighting up at all. The fuse and tubes look fine as far as I can tell.

 

I know this amp had problems with blowing fuses. Did that ever get resolved? Anybody have similar problems?

 

Thanks

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Jamie, welcome to the forum and sorry to hear you're having amp troubles.........

Noob or not, you did the wise thing taking it to a tech.

All that said, fuses usually blow for a reason........and the solution will be to find the reason.

Were you using the same guitar both times? how is the amp grounded(if at all)?are you using effects pedals? did the tech check the tube sockets and wiring? etc.etc.etc.

 

Heres one idea..........make a similar post in the "lounge" section, because it's viewed more often than this section by at least 10-1, and there are some really educated, experienced, helpful & friendly people that come here.

 

Good luck !!

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Hi Jamie, welcome to the forum. Sorry to hear that you're having problems already but know that you're not alone. I bought my amp used almost 2 years ago and just recently started having the same issue of the main fuse blowing. I have a very good amp tech and I'll dropping it off with him tonight cuz i'll be darned if I can figure it out.

 

There are a total of 9 fuses in this thing. The most obvious one in the big fuse holder in the back of the amp but there is also one just underneath the power plug recepticle (this is what's blowing for me).

 

Here is a thread that discusses the same issue -

 

http://forums.epiphone.com/default.aspx?g=posts&t=11127

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I know what is causing the main fuse to blow. It's a design flaw. The rectifier tube pulls too much current on startup and arcs inside causing the main fuse to blow. I've had it happen enough times. Best start procedure from cold is to switch on the standby switch first, then the main on/off switch. The rectifier will allow voltage through more gradually this way and the other tubes wont get full voltage for at least thiry seconds anyway. Other than that replace the rectifier tube with a solid state rectifier designed to fit straight into the octal base. It will bump up the voltage slighlty but will work fine. My rectifier tubes are now very dodgy because of this, they work but the slightest current increase can make them arc and blow the fuse. If you want to stick with a GZ34 rectifier get a new one and it should be better.

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With any piece of valve equipment I would always switch on into standby mode (assume it is available) rather than going straight on to avoid this very problem.

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Many older amps didn't need a standby switch because the tube rectifier takes time to warm up and allow voltage through anyway. One thing I'm looking into at the moment is fitting limiting resistors to the rectifier plates which will reduce inrush. Check out the tube data for the GZ34. http://www.mif.pg.gda.pl/homepages/frank/sheets/035/5/5AR4.pdf

Most amps don't have limiting resistors and manage fine. Something is very wrong with the design of this amp this amp. I'm wondering if it's the choke not holding back the current flow enough.

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Thanks for all the replies! So when you say standby switch to on that would be blocking the sound or not blocking the sound? Dumb question I know but I wanted to make sure I understood correctly.

 

What would a solid state rectifier do to the sound?

 

I would really like to keep this amp but I can't keep taking $100 trips to the amp tech.

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Switching the standby down to the "STANDBY" position "blocks the sound". This should be standard practice on any tube amp. When done playing switch to standby first then turn off the power. This way the switch will be in "STANDBY" when you turn it on.

 

Going to a solid state rectifier will possibly boost voltage a bit (this is NO problem for the amp).

 

A solid state rectifier will NOT affect the sound since the rectifier is ONLY concerned with the power supply.

 

Tube rectifiers DO affect the sound sometimes. This is typically referred to as "sag". This typically happens (NOT always) when the amp is turned up and the player hits a power chord or a note on the low E and/or A strings. It can also happen if the player is using a pedal that boosts or overdrives the amp. This causes a rapid power draw which is heard as a sagging sound. Some players like this sag and others do not.

 

My BC 30 still has the tube rectifier. It sags. I like it.

 

My Mesa Boogie combo has a solid state rectifier. It doesn't sag. I like it.

 

Both sound great!

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The standby switch is not needed in this amp. Why? It has a tube rectifier which has to warm up itself before it will allow voltage through to the plates on the rest of the tubes. By the time that happens the rest of the valves are sufficiently warmed up and ready for action. If you have a solid state rectifier fitted like me, use the standby switch. When I do go back to a tube rectifier I'll be fitting some current limiting resistors to the plates to slow down the inrush.

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hello folks! well this is my first post too, and unfortunately it's about problems with my bc30. and let's say i'm a hard core newbie. i bought it on "second hand", it was used by another man for less than a year, so i'm the 2nd owner.the amp worked perfectly when it came to my possesion, and it stayed that way for a month. then i tried to see how far it can go off with the volume, so i boosted it to the end. henceforth something happend. i don't know what, but its gain in volume decreased drastically. when the knob was on merely 1/4 of its volume level i blew whole sound of the band away. now i boost it to the end and i barely can hear my self when i'm 30 cm away of the amp. the tubes works fine (atleast i hope so cos they glow their beautiful blue shady light). so there is a sound but it's level is severly deacresed. help please?

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I got some new fuses on ebay and they seem to work fine. I've been leaving it on standby when I turn it on and that seems to do the trick.

 

Unfortunately now it's making fizzing or buzzing noise. I thought it might be my cable but it wasn't that. It does it slightly when I put it on standby and it does worse when I pick one of the low strings sharply. It seems to do it worse on E notes for some reason. Very strange. It doesn't affect it when I have distortion on it (drowned out I guess). It's pretty frustrating to play the clean channel at low volume.

 

I've used this thing for several shows now and it's certainly loud enough. That's been the one good thing about it. I've left it in 15 watt mode and had plenty of volume.

 

So what do you all think? Should I save up for some new speakers or what?

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So I just got my BC30 back today from repair and the problems was ...

 

 

 

... drum roll please ...

 

 

 

 

 

A bad rectifier tube!

 

 

 

Crap, just what you guys were saying. And I asked my tech about going solid state but he did not recommend it as it would put out too much voltage and start burning out tubes. I'll think I'll just play the thing now and not fork with it for a while -

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If you stick with the rectifier tube just make sure you don't use that Standby switch. Leave it switched on, you don't need it. Your amp will thank you for it. My BC30 is running a pair of EL34's with a solid state rectifier. The voltage did go up so I replaced the 250 ohm 25 watt cathode resistor with a 330 ohm alternative to lower the plate current.

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I had a similar fault but I found the standby switch to be arcing.

 

Because we have a 5AR4 rectifier in the BC30, we don't need no standby switch, the 5AR4 has a slow warm-up by design, to allow the heaters to get up before the HT (there's a problem called 'cathode poisoning' or 'sleeping sickness' caused by using standby switches - see article 'standby for the truth' by Hartley Peavey). So I bypassed the standby switch (actually I replaced it with a master volume control).

 

I had already changed the stock Chinese Electron-Tube for a Sovtek, there was a very noticeable improvement.

 

If you would go solid state rectifier check out the SoCal50 schematic (it's the grid-biased EL34 version of the BC30). The BC30 has the same power transformer and could easily be grid-biased too but I don't need it any louder, it's already louder then a Blues Deluxe (honest, we used it for a jam on Friday, I told one lad it was loud but he didn't believe and he drowned the band). We used to get solid state rectifiers fitted to an old valve base, so you could swap over, hmm, that Electron-Tube and some 1N4007 ($0.0167ea min order 1000) ...

 

A Bassman AA864 is biased at -44V (at the pot) for 6L6GC. My BC30 is 35V (stock 250R) at the cathodes and 420V on the HT. I'm running =C= 6L6GC.

What else... removed or lifted C3, C4, C5, C6. Made R15=3k2 and R23=5k6 and C16=660p (3x220p piggy-back) and C17=100n and replaced R39 with 250k master volume, ditched the speaker and fitted Greenbacks. These are all minor changes. Nice and smooth now, the stock job is very harsh. Now if I can fix the heater hum... which clot put a fan motor on it?

 

Check your standby switch, imo they're not well made, eventually mine shot is springs and contacts out the back of the switch, yes it was live too, underwhelmed.

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Lost my clean channel on BC 30. All fuses good . All tubes light. Green light comes on clean channel but not a sound. Swapped all tubes with good ones. Nothing. Channel 2 red light comes on and works seems fine. All internal external fuses check with continuity. ? Thanks for any help . 

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