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Technik => Tech-Talk VOX => Thema gestartet von: bi7340aa am 26.11.2023 11:32

Titel: Vox AC30CC2 5AR4 replace
Beitrag von: bi7340aa am 26.11.2023 11:32

 Hi all!
Does any of the forum members have experience replacing the rectifier on a 5U4G?

Titel: Re: Vox AC30CC2 5AR4 replace
Beitrag von: roseblood11 am 26.11.2023 13:04

Voltages will be a bit lower.
I'd recommend to stay with the GZ34. Add rectifier diodes in series (1n4007 or better), and never use the standby switch. Leave it on or remove it completely.

Titel: Re: Vox AC30CC2 5AR4 replace
Beitrag von: Helmholtz am 26.11.2023 15:00

Not a good idea to use a 5U4G in an AC30.
Heater current of 5U4G is 3A, GZ34 is 1.9A.
So the 5V heater winding will overheat.

Titel: Re: Vox AC30CC2 5AR4 replace
Beitrag von: bi7340aa am 26.11.2023 16:10

Thanks, I know that the filament current 5U4 is 3 A.
But I don’t know what current the 5V winding is designed for...
The transformer for AC30 from Inmаdout, for example, is rated at 3A...

Titel: Re: Vox AC30CC2 5AR4 replace
Beitrag von: Helmholtz am 26.11.2023 16:31

Zitat von: bi7340aa am 26.11.2023 16:10

But I don’t know what current the 5V winding is designed for...

I don't know either, but it seems unlikely that the original Vox PT could safely handle a 60% increased current.

Another benefit of the GZ34 is its delayed heat-up, resulting in delayed ramp-up of B+.
This saves tube life.

Why don't you want to use the GZ34?

Titel: Re: Vox AC30CC2 5AR4 replace
Beitrag von: bi7340aa am 26.11.2023 17:42

My 5AR4 is dead and there is no replacement. But my friend offered help in the form of 5U4)))
I have already ordered a new 5AR4, so the issue can be considered resolved.
I thank everyone who cares! :bier:

Titel: Re: Vox AC30CC2 5AR4 replace
Beitrag von: Helmholtz am 26.11.2023 17:52

I guess you know that 5AR4 is just the american name for a GZ34?

Titel: Re: Vox AC30CC2 5AR4 replace
Beitrag von: bi7340aa am 26.11.2023 21:39

Yes, sure. Thank you :topjob: