Help with Vibrolux Reverb

[ratgon]

Hey all and thanks for your time. I've been building a VR, and it seemed to be going well, but as I've started up the initial power-up procedure, I'm running into issues. The negative bias seems to be working fine but I can't get any voltage on the plates. At times it comes up and then it's gone. I'm rebuilding the filter lineup in the doghouse, so we'll see, but I can't see how no voltage is getting to the plates unless it's a screwed up OT. How can I check for that?

I'm open to any help at all. I'm all ears and ready to learn. If there are any oics that would be helpful I'm happy to post them for you.

Thanks again,

Mike

[glass54]

Schematics as built? Maybe a photo?

[stratomaster]

Take the tubes out and do a full voltage survey.

[pdf64]

Providing photos and a link to the schematic and layout that you've used to build the amp would be a good idea.
Here's Fender's original, but I assume youve built it from a kit 
https://el34world.com/charts/Schematics/files/Fender/Fender_Vibrolux_Reverb_AA964_schem_layout.pdf

[ratgon]

I used that exact schematic and layout - AA964. I didn't build it from a kit. I just slowly assembled all the parts. I'll send some pics as soon as I'm done rebuilding the filter caps and hooking them back up to their proper points. Thank you for your patience

[ratgon]

Thanks again for all the inout. I have photos now and voltage readings without the tubes

Voltage fro neg tap fro PT is=47.01

Negative Bias is -56.21 to 38.o1

Plate voltages are both -4.17 V

Thank you all. I'm baffked unless the OT is screwed. It a hammond 176OJ

Thanks for your time. I;ll attach th erest of the photos on the next post

[ratgon]

Thanks. Here are the last few

[AlNewman]

Do you have screen voltage at pin 4 of the power tubes?

You can test the OT by measuring resistance across the red/blue, red/brown leads when the amp is off and discharged.  Both sides should read fairly close to the same measurement.

[dogburn]

One thing I might suspect is that some part of the circuit isn't properly grounded. Another thing could be if the rectifier is not wired properly - could you have the socket rotated 180 degrees from how it should be oriented? And have you measured the high voltage secondary wires coming from the power transformer to confirm that is working?

[passaloutre]

The photos are not consistent. For example the first few show two leads connected to the ground bolt near your bias pot, but only one in later photos (and a stray crimp ring terminal that appears to be just lying there…). You say you followed the Fender layout but there are discrepancies in your own photos. I’d start by making sure your layout matches what you think it is. Print it out and use a highlighter as you check each component.

If you’re concerned about the OT, maybe check the DC resistance of each lead.

[pdf64]

Hey all and thanks for your time. I've been building a VR, and it seemed to be going well, but as I've started up the initial power-up procedure, I'm running into issues. ...

Are you using a documented start up procedure, if so it needs providing here, if not then note it down.

[pdf64]

A light bulb limiter is simple and cheap to put together, extremely beneficial for protecting new builds from wiring errors etc, yet most new builders seem they'd rather not bother with one, end up with avoidable damage.

[pdf64]

... I can't see how no voltage is getting to the plates ...

Just to note that the valve rectifier in V9 socket (GZ34 /5AR4 here) must be fitted before any high voltage HT V DC can appear.

[ratgon]

Thanks for the inuout and appologies for the photos. They do indeed show both leads properly grounded now, I;ve tested tyhe OT and it seems fine as well. I now get plate voltage but aI;m now trying to sort out biasing. Throughout this process I blew three fuses and burned out the 470 2 watt resistor twice. And it does pass signall. It seems week and theres no trem but it does pass guitar.

Thank you all in advance

[stratomaster]

You have major issues and need to take a huge step back. Stop feeding this amp components to kill, and start strategically troubleshooting. There should be no power tubes in this amp for the foreseeable future.

There's a lot of questionable soldering and collateral damage from careless iron manipulation. It would not surprise me if major sections of this amp need to be completely reworked.  But in the meantime you need a way to limit current into the amp, so a bulb limiter would be the best next move.  From there you can start finding why things are failing.

[ratgon]

Hi there. I truly appreciate the comments, and I've no doubt you're right, but could you give me at least a couple of specifics to start working on? Believe me, I have no ego involved with this. I'm just trying to learn as I go. Any and all advice, no matter how pointed, is appreciated. Truly.

Mike