Ceriatone Forum

Hi guys,

I just moved to a new house back in January, and finally got a chance to set up my amp.  Problem is, no output.  This amp was built by Ceriatone, with some mods/finish work by Henry (tenguitars) of this forum.

Here's what I'm observing:

1)  My c-lator seems to be receiving input from the preamp.  I have a Lexicon reverb unit in the c-lator, and it's got an input meter showing a signal. So, I'm reasonably sure the preamp section works.

2)  I bypassed (unplugged) the c-lator to isolate the rest of the amp - no luck.

3)  The output tubes LOOK fine.  (I realize that's hardly an adequate test.)  I did pull the inner pair, and then the outer pair, both with no luck.

4)  The speaker cabinet and speaker cable are working -- I tried them with another amp.

So, that seems to narrow things down to somewhere in the output section, possibly excluding the output tubes.  I think that leaves the OT, speaker output jack, impedance switch, other?  Could one of the 12AX7s be causing this? Because these amps are relatively complex, I thought I'd run this by you all before I start buying new output tubes or an output tranny. 

Any thoughts or ideas?

Thanks much in advance.
Tim

swap your 12ax7's to start. If that doesnt work pull the chassis and get some voltage readings, check for bad or even unsoldered connections that may have been disturbed during your move.

Todd

Thanks Todd.  (Would love to hear about that TW Express clone sometime.)

I've swapped out each 12ax7 (serially) for a new one.  Still no luck.

I can pull the chassis and get voltage readings, but it'll have to wait at least until Wednesday and possibly until Saturday.  I inherited a nice big workbench from the previous owner, so that should be relatively painless.

Is there a voltage chart somewhere on here for the OTS 100 FM?  My search turns up a bunch of folks posting voltages, but no generally accepted list of what to expect.

I'll be surprised if a connection came loose in the move, as I moved the head myself in the back seat of my car, and it's already survived shipping from Asia to Southern California to Maine.

Thanks again for your suggestions!

Have you tried running it without the c-lator?

Gregg

Gregg,

I have - see #2 in my original post.

Thanks.

ah ok, i misunderstood what ya meant.

hmm. if you inject a signal into the return side of the loop on the amp do you get anything?

Gregg

Hey Tboulette

The ceriatone website has a voltage chart that covers most of the amps in the links section. a very handy chart.

As for the TW express, I could not seem to bond with that amp. It is very raw and loud. I left it at a friends house who is in a punk band hoping he would find a use for it and although he likes it a little more than myself he prefers his JCM800. maybe turn it into a rocket or liverpull and see if I like those circuits better.

Todd

Thanks Todd.

I've never heard an Express, so no idea how it sounds. Funny how folks have very different ideas about tone.

Hi Tim,

Sent you a couple more emails.

Thanks,
Henry

Thanks as always, Henry -- I've sent replies.

For everybody else helping out (which I really appreciate, BTW): I've run a signal into the effects return without any change. One thing I've noticed is that I'll get sound fading in and then back out when I switch off the standby switch.  Not quite sure what to make of that.

EDIT: planning to pull the chassis tonight and poke around with a chopstick.  If I have enough time, I'll also take some voltage readings and post here.

Have ya checked the HT fuse?

Gregg

I haven't.  I don't know what the HT fuse does, but I figured if any fuse is shot than there shouldn't be a pretty light on the front panel....    :-[  No?

The HT fuse is the fuse on the HT (high voltage) winding of the transformer, in other words the voltage to the plates, screens, and grids of the tubes when you switch the amp off of standby to operate. It is located on the bottom of the chassis. The light on front will not glow if the mains fuse is blown, in other words, no power will go from the mains to the power transformer at all. That is the fuse on the rear of the chassis.

Gregg

OK, thanks.  I'll check it.

Might have a winner, Gregg! Looks like the HT fuse is blown. It's too late to get a new one, but I'll try to pick one up tomorrow and report back.

cool!! word of advice, get a 5 pack. the reason? something made it blow. if you replace it and it blows again, then the real troubleshooting begins, for example, starting with the tubes, if they short or red plate, it can blow the fuse... let's hope it just randomly blew :)

Gregg

Here's a question:  The layout on Nik's site calls for a 1A 250V slo-blo.  The fuse I took out is a 500mA.  Anybody know what I should be using?  :-\ (Fortunately, I just bought some of both.)

Tim,

It should be a 1 amp FAST blow fuse. The layout has this wrong, but the manual corrects it. Slow blow for the mains 3 amp with 120 v, 2 amp with 240 v; and 1 amp FAST blow for HT.

Thanks Gregg. Back to Radio Shack I guess.

Hi guys,

Picked up some 1A fast acting fuses, and replaced the old 500 mA fuse. Everything is working great! Thanks everyone for your help!

Tim

Glad to hear it!!

Gregg

Get a few. There might be an underlying reason for it having blown, then it'll be back to troubleshooting.

I agree, although, having a 500ma fuse in a spot rated for 1A maybe the cause... hopefully.

I hope that's the case. But, I do have spares.