18 responses Add your response
Are the broken pins used in the tube circuit? If not then no worries.
If they are and you want to try saving the tube I would insert the "repaired" tube into a tube socket saver. Then if the repaired pin breaks it would be stuck in the socket saver.
You could lose vacuum on the tube soldering on the pins? If so you get a nice light show at least.
The tube is not that expensive. About $50~70. If bought from Russia or Eastern Europe, $60 for 4 set and $25 for shipping.
What I will do is to find some tubes with long legs (at least 50% longer then 6C33C tube legs) and remove them from the tube. Then insert them into the 6C33C tube socket. Then you can connect the the pins and the tube's (with broken legs) legs with wires.
How does it sound?
Why not just by a new tube and use it? I know it sounds stupid to go through all these hassles, but I need to buy not one, but four matched set of tubes, and I've ran out of audio upgrade fund. LOL
Until I get a new matched quad set of tubes, I will try what I just said unless somebody yells me hard not to go for it due to potential hazard to the amp.
I once purchased matched pairs of 6C33Cs from BAT for use in my Atma-sphere amps. You might check with Victor Khomenko, if you live in the US. Any extra cost was well worth it, since the first set of tubes have lasted nearly 10 years with no failures and all still bias well. As to the repair job, yes I think it could be repaired and a proper solder joint is not going to break off in the socket. The bigger hazard is that heat from the solder gun could cause a fragile internal wire to go up in smoke, causing a short. I would opt to throw that tube away.
Ihcho, I have been through many retubings of VK75SE without matching. From the owner's manual: "...implements a sophisticated autobias circuit that automatically compensates for tube aging and line fluctuations, as well as marginal mismatching of tubes." Moreover, IME in BAT amp these tubes deteriorate sonically after 1200 hrs. The improvement gained through frequent retubings is likely greater than the effect of scrupulous matching. Finally, for what you propose to pay you could be making dramatic mods to that unit.
Dear Ihcho, It was several years ago that I bought the 6C33Cs from Victor. I bought two sets of six matched pairs each. At that time, I think Victor had the inside rail to obtain tubes that had been built in the Ulyanov factory in the early 90s. Those are said to be the best run of 6C33Cs. I either paid $80 per matched pair (i.e., $40 per tube) or $100 per matched pair. I really think it was the former amount. But bear in mind that this transaction might have taken place as long as 10 years ago. Anyway, since you have a BAT amp, they should give you some sort of deal, but it would have to be based on current values. You have a high-end amplifier; why compromise on the output tubes? They will last a long time.
Newbee makes a good point. But you do have to feel confident you have a firm contact that won't short out during use. Also, as I recall the ceramic sockets for the 6C33C are fairly thick before you reach the metal contact points, which places a constraint on how short the pins can be and still achieve reliable contact.
There is no leg left on the damaged tube to make any contact to the socket.
Someone told me that the broken legs may not need any connnection to the circuit. So I just go ahead and plug the power.
Only one tube biased (a green line comes for each tube once biased). One tube did not glow at all. The other two tubes glowed, but did not bias.
Looks like three tubes are bad. The seller claimed that the amp worked just fine before shipping. What a life on used power amp!
In another thread (under misc forum) I mentioned that one int tube amp, which worked find before I sold it, was returned back to me with blown resistor. The seller demands a full refund minus shipping, claiming that I sold him a defective amp.
I feel like I am cursed by a tube daemon.
Dangerous to just take a chance that the missing leg is irrelevant. In fact, as far as I know, there is NO irrelevant pin on a 6C33C. Anyone who told you that is "blowing smoke". Here is the pin diagram URL. I believe pin 4 is the single large diameter one, so you can use that for reference:
By the way, pin 4 is the single "plate" connection. Pin 5 connects to both grids, and pin 3 connects to both cathodes. Despite the presence of dual grids and cathodes, this is not a dual section tube, because it has only one plate. The other pins in pairs subserve the filament connections. If you light only one filament (by omitting a single filament connection), then the tube is reduced in its ability to handle current, at the very least. Also, these tubes are not internally fused, so if they are overloaded they will arc.