Anyone ever run into this problem? Where to run?

[70sSoundQuality]

My mom recently saw a posting for a free tube amp and tube radio with record player. I raced to the chance to get it. I called the poster and he said the unit worked 100% fine. He had to disconnect a few wires and cut a few to get it out of the console, but since it worked before hand, I can see that the tubes aren't bad and the transformer isn't bad. The guy wanted to keep the console as an art piece, and just removed the guts. I just wanted to use the amp as a little "pre amp" for my bass guitar, to draw a different sound that probably wasn't designed for bass, or instruments per se.

When I got the amp home, my friend accidentally bent in one of the tubes. One of the metal poles at the bottom of the tube snapped cracking the glass and letting all the gasses escape the tube. Once I got inside the house, I still tried to plug it in to see if the other tubes would light up, but to no avail.

On the amp itself, there are four cables sticking out that were cut, which attach to the record player I have. Then there are two plastic grid plug-in ports for the radio, located on top of the amp. I get the feeling the tube amp should work as a stand alone amp, regardless of the fact that it isn't connected to the rest of the components. Im just confused since the amp was working, and now it won't draw anything. Is it because of that broken tube? Would the circuit breaker prevent the amp from turning on?

A repair guy on the phone said I should just throw it away since it would cost more to fix. I insist on making this amp work just so my parents don't feel like the drove 1.5 hours out of the way for nothing. And I hate guilt. Im just curious if anyone here has any clues, or if they have had an amp simply not turn on.

The tubes are,
-6BQ5 (2 tubes. One broke)
-12AX7 (1)
-6V6GT (2)
-5BC3 (1)

Thank you for any bit of help you can give me. I just feel like I cant let go of this amp quite yet, and repair guys on the phone tell me this would be "custom trouble shooting" that would cost me much more than having a brand name amp fixed up. By the way, the brand on this amp is Motorolla, and I was told it was from 1947 or so.

Thanks,
Best
Jhn

[toddyjoe]

In almost all cases, a 6BQ5 (known as an EL84 in Britain) is an output tube. If you have two of them, they might be running in push-pull configuration. If so, breaking one will mean you have no output. However, from the pic of the amp, I see some extra transformers on there which suggests it could be running the 6BQ5s in parallel single-ended form. You should still have some output then. Do you know whether it is push-pull or single-ended?

As you might know, tube amps are going to need a proper impedance load on the secondary of the output transformer(s). Otherwise, you may get a bad sound, a very weak sound or no sound at all. Without a load, you risk damaging tubes, resistors, capacitors, transformers, you name it. For those of us who scrounge old tube radios and record players for guitar or bass amps, the transformers are often the most valuable piece we get for little money. If you did not hook up a load when you fired the amp up, you may have fried some parts. Unfortunately, if you fried a transformer, you might give up on this project and part it out because a replacement transformer just made your project a whole lot more expensive to complete.

What kind of shape are the power supply's filter caps in? Most amps with filter caps older than ten to fifteen years may need filter caps replaced. Filter caps dry up with age and even faster when the amp is not in use. This may be a problem with your amp if it is as old as your post suggests. If the filter caps are dried up, they may be shorting the power supply rail to ground. If so, you are going to get no sound and may have blown a fuse if it has one or, even worse, damaged the power transformer. As before, if you toasted your power transformer, you may be parting the amp out rather than fixing it.

Not to sound discouraging, but bringing an old tube radio/record player back to life and converting it to a guitar amp can be a major project. You need to have some knowledge and/or experience with amp repair or amp building to even get started on the right foot. But they can be great learning tools for someone who already knows how to drain filter caps, do basic repairs and tweak some aspects of a guitar/bass amp. For a complete novice, a tube amp kit might be the better way to go because the challenging design and tweaking work is already done for you and you can save your time and money focusing on building it cleanly and correctly.

I am going through a similar circumstance with an old tube amp right now. I picked up an old Olympic tube radio recently for cheap. I had to part it out for some of the above reasons but am combining what is left with some new parts for a Matchless Clubman-type amp with 6V6-GTs and 7-pin preamp tubes. I have been playing inside tube amps and repairing them as a hobby for a few years now, but trying to turn something old and intended for a non-guitar purpose into something usuable for guitar has tested me at times during this process. I have learned three key skills so far: (1) patience; (2) persistence; and (3) swearing.

Good luck!

[70sSoundQuality]

Jesus!! thanks for that answer!!!

I found out the transformer isnt getting anything

thanks anyway!