heathkit aa-151 advice please
- Thread starter jntit
- Start date
If you are positive that the tubes aren't lit and sometimes it's hard to tell, then either both tubes are defective which isn't likely, or there is no power to the tube filaments from the connections off of the 6AU6's. Each 6EU7 is powered by a separate 6.3 volt winding from the power transformer for both the left and right channels which powers all of the tube filaments for each channel. The filament connections on the 6EU7 are pins one and two. Check for voltage at those pins on each tube. The voltage will be AC. If you don't have 6.3 volts at the tubes, check for broken connections from the 6AU6's to the 6EU7's. Pins three and four on the 6AU6's are the filament leads. If you don't have the service information for your amp you can go to the HI Fi Engine website and download it for free.
There is also the possibility that the tube sockets have failed as they weren't all that good when they were new. I have had to replace sockets in both of my AA151's due to them breaking. Fortunately since they were kits, the sockets are easy to replace. Also since the amp was built from a kit, possibly by someone with little to no experience in soldering, you could just have a bad solder joint or joints causing your problem. Try re flowing the solder joints on both tubes before doing anything else as that could solve your problem.
