My first build, What should I do before thuning it on?

[marcoloco961]

I'm curious, what OT does Your clone use? Could you tell me how it is hooked up? you should have one batch of four wires ( black, red, yellow gray??) and a second with only three wires. What color are the three wires from the OT secondary? And how do you have them hooked up (to which pins or components)?

[Mont]

I am using heyboer tranny's I got from rjguitars. the green and purple are connected to pins 3 ofthe out put tubes and the blue is connected to the standby switch. on the pt, browns are my heater, pins 2&7 on out put and 4-5 to 9 on preamp.two yellows to diodes. red\yell & brn\white to ground. the two gray and yell\green i cut short and put heat shrink on the ends.

[geetarpicker]

I'm not sure what happens "if" they are in backwards but are your output diodes wired with the proper polarity?

FYI my Express is darn muddy without the bright switches. Yep, the 500pf position is a tad too bright but I find the amp almost unusable without it!

It's odd that typically most (all?) clones run on the bright side compared to an original Wreck. I wonder why that is? It's not just an age thing, as I have plenty of recordings of my amp when it was new and it was never all that bright. Oooops, going off in a different direction...

Back to the amp in question...
Even with a test bulb you will probably see some filament glow if you dim the lights in the room and wait a few minutes. Heck it may even play and hiss quietly with the bulb limiter if you let the tubes warm up a while. Is your 125v pilot light a neon type? Some neon bulbs won't work at lower voltages and start to flicker off or not work at all. You might check the voltages going into the pilot light and see what you are getting there with the tubes in and the bulb limiter still in place. It's quite odd that you are seeing some normal voltage readings but no pilot light. Probably a neon one reluctant to start at like 100v or whatever it's at with the limiter. Heck while you are at it check the wiring of your power lead coming in. Make sure your neutral and ground aren't swapped. That might do weird things if they are swapped and/or your bulb limiter is perhaps missing the ground connection.

[paulster]

I'm not sure what happens "if" they are in backwards but are your output diodes wired with the proper polarity?

If they were in backwards then they'd begin conducting immediately since the plate voltage is above 3V (3x forward drop in one diode) which would then short the plate to the chassis.

I thought for a moment this could be the answer, but it wouldn't make any difference whether or not the tubes were in or not.

And even with the bulb limiter I think there would have been that classic pop sound and smell of burnt silicon as the diodes quickly expired!

I still think it has to be something related to the tube sockets as adding the tubes is causing the difference.

As an aside, can anyone in the US (or another 120V country) with a bulb limiter start their Express up on it and see how it behaves with a 75W or 100W bulb for reference? I know that mine (at 240V) was sucking gobs of current at idle because of the size of the PT and the amount of filtering.

[M Fowler]

If the pilot light is wiring in series instead of correctly off the power switch the current will be directed through the pilot light causing a drain. Not the first time that has ever happened.

I think its to do with the limiter and pilot light, both should be eliminated for a test.

[Mont]

All the diodes are correct. the pilot light is not a neon type. I made my bulb limiter using a 3foot extension cord, spliced open the hot wire(white wire) and put the bulb in series. i read 113 volts at the switch where the light is connected and i have it wired exactly the way it is shown on the express build guide layout.i noticed that on the ceriatone layout the secondary wires from the power transformer are grounded but the build guide says cut them and shrink wrap. i cut them and srink wrapped them is this correct?

[M Fowler]

Black is hot, white is neutral and green is ground.

[geetarpicker]

If you are seeing 113v at the power switch the amp should play right now even with the limiter, plus the tubes should already be glowing. It would sound a little weak (maybe not by much!) but that is plenty to get some sound. So, if the tubes are still not lighting I would look into your filament wiring or possible something is up with the power transformer. You could try completely disconnecting the bias and B+ circuits from the power transformer, and see if you can get the tubes to light. Also removing everything except the filaments might help to isolate the possible short circuit that the bulb tested seems to hint at.

[marcoloco961]

Black is hot, white is neutral and green is ground.

+1

You should be breaking the black wire not the white. This might be the issue. Wire it correctly and try it again. You probably have got yourself a little freaked out over this all. Take a deep breathe, and slow down just a little. You are probably very close to having a working amp. This stuff happens to everyone from time to time. I am confident that you will figure it out and get it working.

[marcoloco961]

All the diodes are correct. the pilot light is not a neon type. I made my bulb limiter using a 3foot extension cord, spliced open the hot wire(white wire) and put the bulb in series. i read 113 volts at the switch where the light is connected and i have it wired exactly the way it is shown on the express build guide layout.i noticed that on the ceriatone layout the secondary wires from the power transformer are grounded but the build guide says cut them and shrink wrap. i cut them and srink wrapped them is this correct?

Yes, the 5v rectifier feeds (gray wires) and the 260v feeds (yellow and green) should be cut and shrink wrapped.

It might be as simple as the bulb limiter being wired wrong. Start there.

[passfan]

My pilot light is fixed so it is not a problem. I set the bias pot at -43 v and tried it with tubes. Again no pilot light, the bulb limiter stayed bright for 15 seconds and the filaments were showing no signs of lighting up so i turned the amp off and again no charge.

This part is key here guys for those in favor of giving it a go , it won't. He loses his heaters with the tubes plugged in. It sounds like the heater feeds are on the wrong pins of the sockets. Do your sockets have numbers on the pins ? Double check you didn't become confused looking between the top to the bottom on your sockets on the pin numbers. Could be plugging the plates into ground with the tubes in ? Just a thought...pics would possibly save the day.

[paulster]

+1.

It also makes precisely no difference on the bulb limiter whether the bulb is in the hot or the cold line unless you've got a short to ground, in which case you'd already have popped the mains fuse.

It's definitely safer to have it in the hot line in that it limits the current that can be drawn off the hot connection via ground if there's a catastrophic error, but where there isn't a short to ground the behaviour will be the same with the bulb in either lead.

It should be rewired for safety, but that isn't the cause of the problems here.

Tube sockets are the place to look.

And the effort involved in head-scratching could probably have justified an entry-level digital camera by now to get some photos up for us!

[Mont]

First of all Thank You for all involved in helping me thru this. inspecting the light bulb socket i sudenly realized it was one of those 3 way sockets. I replaced it with a normal socket on the hot side and YES some sucsess. plugged in the tubes, limiter bulb went down to a small glow, pilot light light came on, and the Bottles started glowing nice and pretty. waited about 5 minutes, turned the stand by to on and got a loud whistle. volume down, all others halfway. any thoughts as to what this is?

[M Fowler]

I told you it was the damn light.

Is that sound a howl? Then reverse the OT primary wires to the power tubes.

[Mont]

LOL. Dont go to the light, Don't go tho the light........Not a howl, more like when you whislte at some really fine ass walking by.