blown LED and power transformer vibration.

[Dirkjr]

Well I completed by Crack build and started testing. All the resistance checks were more or less on target, and the voltage checks were correct (except I was using a heavily used tube for testing so some of the voltages were slightly lower than expected). When testing the LED on pin 8 I bumped pin 9 and fried the LED. This caused the voltage readings on one side of the 6080 to be way higher than spec. Clearly that LED needs replacing. What is the best way to do this? Other than that I noticed that the power transformer bell has the feeling of vibrating indicating electric current flowing into my hand. This instantly goes away when unplugged from the wall and is not dependant on the amplifier being switched on or off. I have felt this in other devices but I dont know if this is normal in the Crack.

[4krow]

I can't speak about the other troubles, but all power transformers will vibrate to some degree as associated with the 60hz frequency fed to them from the wall outlet. What you are feeling is not current entering your hand, but simply the vibration from the transformer. If it is excessive or makes more than a little noise, it can be considered normal.

[Doc B.]

You can send an email to [email protected] and request a replacement LED.

[Paul Birkeland]

(except I was using a heavily used tube for testing so some of the voltages were slightly lower than expected)

Just to add to this thread, a worn tube will exhibit higher voltages at terminals 1 and 5 (for the 12AU7) and at 7 and 9 (the 6080) than fresh tubes.

-PB

[Dirkjr]

(except I was using a heavily used tube for testing so some of the voltages were slightly lower than expected)

Just to add to this thread, a worn tube will exhibit higher voltages at terminals 1 and 5 (for the 12AU7) and at 7 and 9 (the 6080) than fresh tubes.

-PB

Hmm... once I replace that LED, I will have to recheck the voltages using the never used tubes I have. For voltage testing I used an RCA 6080, and a GE 12AU7. Both of which tested fairly low. The only voltages I noticed to be off by more than a little bit read 80 volts instead of 90. I will double check this with a second volt meter.