rock ola 430 amplifier failure???

hallo! i am David from belgium
i am in love with my R-O 430 wallmount :) but now she is letting me down :(((
amplifier code is 41710-a

it was playing very good. (but sometimes the sound cracked when i turned the volume button)
a few weeks ago it started to buzz loudly every time the record started playing, the buzz stopped when the record ended

now suddenly the music completely faded away and there was a smell like old french cheese :(((
the amplifier fuse was blown , the rectifier was destroyed
we put a new rectifier but the fuse blows again and there is no sound but the tubes are glowing
where do we have to search for the problem? outside the amplifier?
everything else seems to work well: selections write in write out turntable lights etc
please help me fix my baby!
thanks

ps, i don't know anything of electrics, but my dad is helping me, he is an oldschool electrician,

If an electronic device starts to behave different from normal, it's never a good idea to ignore it.
Vintage equipment should only be used, or even connected to the mains, after restoration! The parts are more than 50 years old and may cause expensive damage or even fire, if they fail! And some of them will fail, like you can probably still smell.

The loud hum may have been caused by defective electrolytic capacitors (large cans) after the rectifier. This overloaded the rectifier, causing it to fail. Old selenium rectifiers smell like rotten cabbage, eggs or cheese when they burn.
Now the capacitor has developed a short, resulting in a blown fuse. If you have bad luck, the transformer has been damaged too.

You should at least replace the filter capacitors in your amplifier. A modern silicon rectifier is not an ideal replacement for the old selenium one. It has a much lower voltage drop. So you should add a resistor in series with it.

If you want to read more: [w3hwj.com]

Hello kleindavidje

As you yourself have no knowledge of electronics, I would advise to give away the amplifier and have it repaired by a professional. I do not think that the knowledge of your father, who is an electrician, can be very helpful. For the repair of the amplifier are electronics knowledge and experience in working with tube amps required. Very expensive parts may be damaged if you try - without this knowledge and experience - to repair it.

Best regards - charly49

Marc schrieb:
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> Now the capacitor has developed a short, resulting
> in a blown fuse. If you have bad luck, the
> transformer has been damaged too.

omg, this is bad news

do you mean the big main transformer on the powerboard, or the small ones on the amplifier?

thanks to you both for the explanation and good advice
i will look for a professional to diagnose the amplifier

one of the symptoms was the amplifiers mute position , when there was no rekord playing on the turntable
sometimes the rekord already was playing 5 seconds before the amplifier turned on
sometimes the amplifier did not mute when the rekord was taken of the turntable

how expensive is an amplifier or transformer rebuild, just to have an idea?

The two transformers on the amplifier itself are the output transformers. If there's a third one, it is the power transformer for the high voltage supply. The filaments voltage is supplied by the main transformer.

A damaged transformer is not very likely if the correct fuse was used.
The muting problem is another problem, muting is done by a relay. However, if the volume came up slowly with distortion at the beginning, this has been caused by the rectifier.

Hello kleindavidje

I hope that the transformer has no damage. Rock-Ola transformers are rarely defective, different from eg Seeburg. If you give the amp to a professional, you should nevertheless give the power supply as well, so it can also be checked. You should also give the volume control with, because the crackling when turning indicates a faulty potentiometer. This can probably be fixed by spraying with contact cleaner.

The problem with the mute is probably not very difficult to fix. You should, however, point out the professional, because sometimes it is forgotten as the amplifier works even without muting on the bench.

It is not possible to specify the cost, without having seen the amplifier. Normally, the repair does not exceed 2 - 3 hours. It is therefore expected costs for the working hours of about 100 euros. Then there are costs for the required spare parts. These are usually in the range of 100 - 200 Euro, depending mainly on the condition of the tubes and other expensive parts.

Best regards - charly49

i am very thankfull for all your help and advice, guys!
i already phoned a hifi -shop in my town, specialised in old (tube) amplifiers who is willing to test and rebuild it for me