F51 fender doesn’t turn on

[Winterjacketz]

Hi im looking for someone to help me find whats wrong
there is no light when plugged in light tested ok fuse tested ok one of the tubes has litlle broken glass inside.
can you tell me what to test?
i have tried some testing some connections with multimeter but it is blown now, so good news there is high voltage inside..
thx

[mozz]

You're not going to get advice here if you blew up a meter probing around. There are many safety rules to apply and be familiar with before you actually start troubleshooting. You can get killed.

[Chuck H]

We do not know the provenance of this amp. It (reportedly) has a tube with broken glass inside? And it doesn't come on. That's all we know right now. Encouraging you to continue based on this vague report with no reference to your skill level would be irresponsible. The image I'm getting (correct me if I'm wrong) is that you acquired this amp and it didn't work when you plugged it in and you have no electronics experience. Sorry to say, but, whatever savings you got on the price of the amp for it's condition will now be undone by the necessity of having it perused by a professional amp tech. But this is usually how it goes so don't take it too hard.

[Winterjacketz]

Thanks for the replies,
I do have basic common wense skills,
and I have ordered a more powerful multilmeter.

I was being careful when probing and using
a diagram of layout.

Are there some basic checking I could do,
that are not dangerous?
i find it strange that the on/off light doesn’t come on.

This amp was given to me so indeed I wanted
to plug it in and give it a try.

I find the fees of getting gear repaired way too high,
so I might store it, without hearing its nice tube sound.

[Chuck H]

There are threads here, available with a search, that cover safety procedures for working inside amplifiers. I'll just note here that tube amplifiers operate at hundreds of volts and large capacitors in the power supply can store charges at that voltage and deliver significant current if they discharge through you. And though it's not always likely this CAN happen even with the amplifier off and unplugged. So please look into safety procedures for working inside tube amplifiers.

A 5f1 is definitely an amp anyone would at least want make operational so it's not languishing in a closet. I guess we don't know of any particular reason the amp isn't working now or why it may have an internally broken tube. There are things that can happen to an amplifier that sits unused or maintained for long periods of time. The large capacitors I mentioned have a life span of ten to thirty years or so. Sitting unused makes this worse and there's a good chance the amp you have would need to have those replaced. Contacts in jacks and tube sockets can oxidize causing intermittent faults.

Also a safety concern would be that this amp wasn't made with a safety ground on the chassis. That would be a three pronged AC cord that requires specific, but not complicated knowledge to install properly.

It's impossible to say why the pilot lamp didn't come on. It could be anything from the power transformer to the lamp itself.

Please read up on safety procedures. You're going to have to open it up to continue.

[Winterjacketz]

Thanks for your reply,
ok I will check it out.

the power chord only has two prongs, so I guess
it is the original one.
I am in france so I am using a 220 to 110 converter to plug it in.

I have tested the lamp with 9v it works.

The person who owned it before me could have very easily fitted a 110 to 220 plastic travel adaptor and pkugged it directly into the 220 v.
and if this happened that could probably help to knpw what went wrong.

The power chord looks like it has been pulled hard where it goes inside the power supply, probably when someone catches it with their foot. The grey plastic outer layer appears damaged on the last inch.

[g1]

With the amp unplugged, connect your meter probes to the 2 prongs of the AC cord. Set meter to resistance range. Turn power switch on, what is the resistance shown on the meter?

[Mick Bailey]

Could you post some pictures of the inside of the amp? It helps to know what's original or not and to see the general condition. If the amp had been plugged into 220v this would have at least blown the fuse and possibly damaged the transformer to the extent that you would not get any voltage out of it. Having enough voltage to kill your meter suggests that this has not happened. Do any of the the valves light up? There should be an orange glow from the heaters.

[The Dude]

The first thing I'd do is pull the lamp and check it for continuity. It's a simple and easy test that does not require disassembling the amp. It could just be a bad lamp. Does the amp produce sound, or are you just going by the power indicator?

[Mick Bailey]

He already tested the lamp and it works. Could be a bad lamp holder, missing 6.3v, or maybe something else entirely.

[Chuck H]

After searching a bit on the forum I was surprised how much safety info I DIDN'T find. Which seemed odd as much as we've covered it here. It comes down to the info being hidden in threads for specific amp projects and the limitations of the search engine. So... Here's a pretty decent rundown from good guy Rob Robinette on his site.

https://robrobinette.com/Tube_Amp_Safety.htm