Discussion in 'Amateur Radio Amplifiers' started by N9EVD, Nov 7, 2019.
Thanks for that information.
No, I have not fired it up yet, just wanted to confirm my connection of ground wire to neutral in the plug, since they were not connected internally.
It is now connected like our 220 volt clothes dryer with the 3 prong plug.
Power it up!
Maybe just filaments first with the plate connections removed (be careful they don't come close to anything metal -- and make sure to push down on the HV interlock with something...actually the plate tank/tube compartment cover laid in place and held in place with one or two screws would be a good idea).
That tube with visible glass blemishes is suspect, but who knows? -- it might be okay. Never seen one like that. But the tubes you pictured appear to have had very little actual use; I can tell that by the red color of the ink on the glass. That ink is temperature sensitive and when the tubes get hot enough, long enough, it fades to a dark orange and not red like yours are. And that's normal, they all do that.
OK, so I powered it up with the anode connections off and the protection bypassed. Soft start worked, a hum was heard, filaments lit up brightly, then after a few seconds there was some ticking sounds , then sizzle, pop. I shut her down immediately. I definitely let the smoke out of something, could not see any smoke, but I could smell it. I am guessing it was either the fan that was not able to turn and blew a winding or it is an electrolytic cap. I am guessing the latter. I will have to investigate after it sits for a while. I checked to make sure the HV is no longer present.
Any recommendations for replacement electrolytic caps in case they are needed. Probably not a bad idea to replace anyway, sit it has been sitting for a while.
You can check the blower (power off) just trying to spin the cage with your hand. With power applied, you should have been able to "hear" the blower, as it makes noise.
Did you power it on in the CW or SSB position of the switch on the power supply front panel? CW is easier on the capacitors, as it produces lower voltage. Did the panel voltmeter indicate anything?
If you shut it down manually and the circuit breaker didn't shut it off, you don't have a hard short circuit but obviously something was wrong.
Blower checked out OK
Henry made various changes over time without necessarily updating documentation.
In most 2K Classics I've seen, there's a separate fuse for the low voltage transformer which they call the "AC control" fuse, F102 or F2 or something, and it's a 3AG 1.5A fuse in a special holder. If that's in place, the correct rating, and didn't blow, then the LV transformer is "probably" okay. A short in any of the HV rectifiers D101, D102 would normally blow the circuit breaker before doing any damage but it's impossible to know for certain. The filter caps C105-C112 are all 180uF, 450V each (8 of them) and modern replacements are not difficult to find if that turns out to be a problem.
Last I checked (couple of years ago), Harbach was selling complete kits of these capacitors (all 8), rated 210uF at 450V and I believe drop-in replacements for the original Cornell Dublier parts Henry used: https://harbachelectronics.com/shop...μf-450vdc-filter-capacitors-with-sems-screws/
An amp that's been "sitting" a long time without being powered can have a variety of issues, but the 2K Classic is a good amp and should certainly be reparable.
I started it up on CW. Blower motor is confirmed good. I ran 120 to the blower motor and it ran good. I did not notice the meter deflections, if any. I pulled the back off and am inspecting and sniffing to determine what let the smoke out. Everything looks good from the back, but can not see the electrolytics very well because they are mounted in front of the resistor bleeders. I will try and take some pictures with my phone on the other side.