Eico ST40 Rectifier

[mikey5967]

Hi guys,

Just wondering if any of our EICO ST40 users here have had issues with the 5AR4 rec, and could a quick power cycle (on/off/on) cause it to go?

Mick

 

[danno2000]

It shouldn't unless it was ready to fail? Is your amp all rebuilt with new filter caps?

 

[mikey5967]

Yes, completely restored.

 

[LinderK]

Tube rectifiers don’t like to be hot cycled. The new varieties especially don’t like it. It could absolutely cause the tube to go.

 

[drtool]

Quick cycle is a bad idea on all tube gear. Very hard on the tubes.

 

[mikey5967]

Yes, that makes sense. I replaced the old rec with a new JJ, ran it for an hour and it sounded fine.
I have a NOS GE on the way to replace the JJ.

 

[egellings]

Be sure that there is not too much capacitance on the 5AR4's cathode. Some recap people overdo that and the peak charging currents make life miserable for the tube.

 

[Pio1980]

Be sure that there is not too much capacitance on the 5AR4's cathode. Some recap people overdo that and the peak charging currents make life miserable for the tube.

40 uF max. Whatever floats your boat after the choke.

 

[egellings]

After the choke, C is no problem. Keep in mind though that if too much steady current is drawn though the choke and its core saturates, then you lose most of its peak current limiting benefit.

 

[billyz]

JJ 5AR4's are not reliable . Sovteks are much better, NOS are the best .

 

[Pio1980]

JJ 5AR4's are not reliable . Sovteks are much better, NOS are the best .

The enhanced yellow sheet mod will even things out. Note doubling the diodes and the jumper from 4 to 6.