Hi all,
An elderly friend of mine had a fall recently and unfortunately fell against his hifi rack - with the result that:
* the rack separated into its constituent parts, and
* all his components ended up on the floor.
I have reassembled his rack, put all his components (well, except for the TT - which is severely damaged!
) back onto the shelves and connected up all the interconnects - so he has his CDP and tuner working again.
However, I am stumped by his Cornet2 - hopefully, someone can advise me:
1. He was using a '5AS4' rectifying tube - however, the manual refers to a '5Y3'. Are these interchangeable ... or is he using the wrong tube?
2. The '5AS4' doesn't seem to have only one way it can be inserted into the tube socket - it seems to fit into the socket any way I choose?? This seems wrong to me - I would've thought that pins need to go into particular holes in the socket. Can anyone tell me which orientation the tube should go?
Thanks,
Andy
An elderly friend of mine had a fall recently and unfortunately fell against his hifi rack - with the result that:
* the rack separated into its constituent parts, and
* all his components ended up on the floor.
I have reassembled his rack, put all his components (well, except for the TT - which is severely damaged!
) back onto the shelves and connected up all the interconnects - so he has his CDP and tuner working again.However, I am stumped by his Cornet2 - hopefully, someone can advise me:
1. He was using a '5AS4' rectifying tube - however, the manual refers to a '5Y3'. Are these interchangeable ... or is he using the wrong tube?
2. The '5AS4' doesn't seem to have only one way it can be inserted into the tube socket - it seems to fit into the socket any way I choose?? This seems wrong to me - I would've thought that pins need to go into particular holes in the socket. Can anyone tell me which orientation the tube should go?
Thanks,
Andy
Hi Andy,
The 5AS4 has beefier specs than the 5y3 and draws more heater current, but it has the same pin out. If it had been working fine it should be safe to continue, main concern would be the transformer winding burning out if allowance had not been left for rectifier subs.
The valve should have a locating pin with a nib on one side on its base, like all octal valves, but these can get snapped off during rough handling, it is possible this has happened here? If so it is also possible that the plastic locating pin is still in the socket, quick examination will reveal. If the valve is otherwise undamaged you can either extract the pin and reattach with epoxy or work out the nib's orientation on the pin and align accordingly. Pin No. 8 would be to the right of the nib, pin no. 1 to the left. Likely there is no pin no. 1 anyway. This is looking at the valve base with it upended. Pin no. 8 will thus align with the hole in the socket to the LEFT of the nib when inserted.
The 5AS4 has beefier specs than the 5y3 and draws more heater current, but it has the same pin out. If it had been working fine it should be safe to continue, main concern would be the transformer winding burning out if allowance had not been left for rectifier subs.
The valve should have a locating pin with a nib on one side on its base, like all octal valves, but these can get snapped off during rough handling, it is possible this has happened here? If so it is also possible that the plastic locating pin is still in the socket, quick examination will reveal. If the valve is otherwise undamaged you can either extract the pin and reattach with epoxy or work out the nib's orientation on the pin and align accordingly. Pin No. 8 would be to the right of the nib, pin no. 1 to the left. Likely there is no pin no. 1 anyway. This is looking at the valve base with it upended. Pin no. 8 will thus align with the hole in the socket to the LEFT of the nib when inserted.
I should have made that last part clearer. Traditionally valve pins are drawn with the nib pointing straight down and seen from the bottom of the valve. Here pin 1 is to the left of the pin. When the valve is inverted to push into the socket the orientation is reversed so pin 1 will go into the hole to the right of he nib, pin 8 to the left, or into the first socket hole located anticlockwise after the nib.
Thanks very much for your input, Jazid. I will examine the tube socket and the tube again when I next go over to his place.
Andy
Cornet2 uses a Hammond 370BX transformer, rated 2 Amps on the 5V winding.
5AS4 filament demands 3 Amps at 5V. So there is a local over-heat issue. 5 Watt overload.
OTOH the 370BX high voltage is rated 58mA and the Cornet2 doesn't suck over 15mA. 10W underload.
And Hammond is very conservative.
I would not expect transformer trouble any time soon. In home use the 370 may give 50,000 hour life and with this wrong tube it may be 45,000 hours... either way may be "a lifetime".
The stock 5Y3 is more than enough for much bigger amps (small LOUD guitar amps), and you might wonder if the original bottle is around the house somewhere.
Yes Octals are "Keyed" so you can't do them wrong. And yes the keys break off when the gear falls off the shelf or an inexperienced tech wriggles them out of the socket. You can see the key-nub in the break, mark the tube, and align by eye. There are Octal nub repair overlays. A new 5Y3 is still an excellent choice.
5AS4 filament demands 3 Amps at 5V. So there is a local over-heat issue. 5 Watt overload.
OTOH the 370BX high voltage is rated 58mA and the Cornet2 doesn't suck over 15mA. 10W underload.
And Hammond is very conservative.
I would not expect transformer trouble any time soon. In home use the 370 may give 50,000 hour life and with this wrong tube it may be 45,000 hours... either way may be "a lifetime".
The stock 5Y3 is more than enough for much bigger amps (small LOUD guitar amps), and you might wonder if the original bottle is around the house somewhere.
Yes Octals are "Keyed" so you can't do them wrong. And yes the keys break off when the gear falls off the shelf or an inexperienced tech wriggles them out of the socket. You can see the key-nub in the break, mark the tube, and align by eye. There are Octal nub repair overlays. A new 5Y3 is still an excellent choice.
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