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I tried firing it up w/the rectifier tube and did not get any glow, and the tube didn't get warm.

Arrgh. Put the rectifier tube back and tried it again, and something was making a buzzing sound every time I turned on the amp. After trying this a few times, I stopped and checked out the rectifier tube. I don't know if there is a proper orientation for the rectifier tube, but I figured that might be the problem. So I rotated it so that the space between the plugs was oriented to an empty solder lug on the tube socket. Tried again and nothing, no AC voltage even on the heater circuit. Checked it out and it looks like I blew another fuse.

Any ideas? I am feeling very dumb right now.

All of the tubes should only be able to go into the socket one way. There is a key way on the 5Y3 tube base between pins 1 and 8. Is your tube socket broken?

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

I guess it is broken ? I can pull the tube out and rotate it and pop it back in any direction. Does that mean I have to buy a new socket?

Is there a simple way to set this up with a SS diode rectifier to save some of the hassle of dealing w/replacing the tube socket? I think I have enough 4007s. Or would that necessitate a whole bunch of other changes?

It is much more likely that the tube BASE has a problem, not the SOCKET. Will you please post a photo of the base of your rectifier tube?

This video shows the spindle key on the tube base and the keyway on the tube socket which are there for proper alignment. It is critical to understand that all tubes can only be install one way. If you manage to plug them in incorrectly, you can start damaging other components in a hurry.

https://youtu.be/JOcCMqGMs1Q

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Ugh, I think you are right. I feel dumb because I've replaced many tubes so I was surprised that it went in so easily in any direction. So does this call for a new rectifier tube? Can I put together a solid state rectifier circuit on the tube socket?

No worries, that’s happened to me before too.

Recommend you replace the 5Y3. Based on your previous description, it is likely blown. It’s always best to get a build working stock before doing any mods. I don’t recommend bothering with a ss rectifier conversion.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Thanks for sticking w/me! I'll report back on this once the parts come in.

Hello, Morgan, I finally got the parts and time to work on the amp again. I removed the bad rectifier tube base (which was stuck in the socket as you predicted) and I
replaced the fuse. I powered it up and got no light. The fuse is still intact, but I don't know what is going on at the bulb.

What can I try now? Thanks for sticking with me!

Not sure how to interpret your last statement. Is the filament glowing in the new rectifier tube?

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No I reverted to step 1 and tried powering it w/o the rectifier tube. the jewel lamp power indicator did not turn on.

Measure AC voltage across the lamp base (one probe on each solder terminal). You should have about 7 volts. If you have 7 volts, the lamp probably burnt out or is faulty.

If you have 7 volts there, go ahead and plug in the rectifier and start over with testing tube operation.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

It works!!!!!!!

Thanks all--esp. Morgan--for sticking with me! Now I just need to find a replacement bulb (so I will know when I have left it on) and I'll have to build the head cab. Hope to post something not ugly soon!

Where are you? I can send a bulb.

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Hello, I spoke too soon apparently. After getting the amp to work in my previous post, I built a cabinet for it--it's horribly ugly but it's at least done. That was a major pain, and then mounting the amp in the cab turned out to be even more of a pain because there's no way to access the screws inside the chassis once it is flush against the cabinet. But I managed to get that to work. Then I plugged it in, put the tubes back in, connected it to a speaker cab and powered it up.....and then nothing.

Oddly enough, the light bulb power indicator did work (as you'll see from the thread above, it wasn't working before). The rectifier tube was glowing and warm. The 6V6 and the 12ax7 were cold and not lit up. Although it pains me to say this, looks like I'll have to pull the amp out of the head cab to troubleshoot. Any suggestions about where to look?

Thanks everyone!

You'll want to check your heater wires first. Make sure the twisted wires that go from the light to the tubes are soldered correctly and have good connections. You should have 5-6v AC across all the pins where those green wires land. Also, are you discharging the capacitors before you work on the amp?

Thank you I'll check those heater wires. If the heaters aren't working would that result in no sound coming from the amp? In general it's so weird that earlier the amp worked fine but no light came on and now I get the light but no sound from the amp.

I admit I haven't been discharging the caps because I've only kept the amp on for a short time. I was thinking I should dischatge the large cap close to the rectifier tube. Are there others that I should discharge as well? How large of a resistor should I use, and is 1/2 watt ok?

The indicator lamp runs off the heater circuit. The fact that the lamp was not working before and is suddenly working now means you have some sort of intermittent connection in the heater circuit (the green twisted wires). Go back through each solder connection on each green wire, inspect the joints, reflow the solder, make sure no stray bits of wire might be contacting something else, take another careful look at the joints on the indicator light base,


Rather than worrying about discharging every time, just measure the voltage on the large cap close to the rectifier (DC voltage, high range, red probe to the positive cap terminal, black probe to the negative terminal or a ground point). If the voltage is low there (<20 volts or so), you're fine.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Like morgan said, if you draw the caps to 0v with a shunt every time, when you power the amp on it shocks the power supply since it's empty. Using the meter tells you when it's safe and may prolong the life of the caps.

Sent from my SM-G970U using Tapatalk

OK, so I pulled out the amp from the cab and found that one of the heater wires had broken off of the connection at the lamp lugs. So, I soldered it back on and tested with power. Now the lamp did not come on, whereas when the wire was disconnected, there was light from the amp.

I went to test voltages at the lugs on the lamp with multimeter set to AC and the probe plugged in to the high current input. and I got an arc of electricity pop out (not sure if those terms are right but hoping you know what I mean) at the test point and immediately pulled back and turned everything off.

I decided at this point there is clearly something funny going on with the heater wiring--even if I can get the amp to make noise, this issue with the lamp is very suspicious. but it is hard to figure out what is going on. Turned off, all of the green heater wires at all of the test points show continuity. As I mentioned, I'm a little scared to take voltages when turned on--perhaps there is something I'm doing wrong with that?

Seems like you were measuring for current, not voltage. That essentially makes a dead short across those terminals. When you test for voltage, the meter's resistance is so high electricity won't flow through it. Can you provide a picture of your meter? Hopefully the transformer is still ok.

Sent from my SM-G970U using Tapatalk

Also, the internal resistance of the power transformer is so low that you cannot test for continuity in the heater circuit unless you disconnect the green wires coming from the PT. You should also remove all of the tubes when you do that test.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

Thank you again for sticking w/me!

@robgar91: I definitely had it set for AC voltage and the meter was registering volts. I had the positive lead in the high-current jack. Is that what you think caused the short? The power transformer should still be ok, it was a very brief event, and the fuse did not blow. Any advice you have on how to check these voltages safely would be appreciated. I am used to low voltage pedal circuits.

@morgan: I did not have the tubes in. I'm prettty sure that continuity is fine in the heater circuit. I can test again but those joints look good. Also, even if there is still a bad joint in the heater circuit, I am not sure why the lamp would be interacting w/the circuit. Is there any reason why the lamp would work when green wire was disconnected and then it would not work after the green wire was reconnected? I feel like this may be the key to understanding the problem but I defer to you on this. Is it possible that there's a defect in the lamp holder that is causing the problem?

Sorry for being so dense. I normally would use the schematic and run my way through the circuit, but here I seem to be stuck at a very simple part of the circuit and I can't figure out what I'm doing wrong.

Let's take a little step back and reset.

From what I understand, you had the amp chassis working but the bulb would not light. Then you mounted the chassis into a cabinet and the light worked but the amp made no sound, and the 5Y3 lit up but the 6V6 and the 12AX7 did not light. Is that all correct?

Also, let's get a fresh round of updated photos showing the current condition of all power transformer wire connections, a good photo of the lamp base, and a good pic of the green heater wiring.

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MasterDelayer/Reverbrador/Ampaholic/TopJacker