Speedball upgrade problems - [solved]

[sadkins]

Just a last update - rebuilt large board with new TIP50' (and using non conductive/heat trasferring pads) and 22N222A's, and I am indeed rolling with my Crack in full speedball mode.  Thanks for the help.

Long story short - terrible idea to think you know better and use heatsink compound on the TIP50's. 

[NightFlight]

You learned something new a bout transistor packages. No harm in that.

[sadkins]

An update since my last -

Woke up to horrible sound coming out of the right driver of my HD650's.  Apparently some component on the big board of the speedball failed, and sent a nice blast of current down the line destroying a driver.

I verified it as far as being an issue on the big board, once again leaving the A & B boards in place and re-wiring in the large resistors in place of the large speedball board.

Prior to this the amp with speedball had been working well, sounded great.  A fluke bad transistor or ? 

[Paul Birkeland]

Did you measure any voltages when this happened?

There are capacitors at the output of the Crack that will prevent this from happening.  If terminals 6/7 or 9/10 are shorted together (by long, untrimmed component leads), then you may end up with the situation you are describing. 

It would be worthwhile to reinstall the large PC board, then measure voltages, as you may still have the same issue present.

-PB

[sadkins]

No, this happened as I was sitting listening to the amp.  Had put several hours on it prior to this from happening, and then the loud, raw voltage sound blaring out the right driver...

I have since taken out the speedball and have been living with it reverted to stock for a week or so with no other issues.  Cost me $50 for the replacement headphone driver, so I'm not too eager to go through all that again without understanding what might have happened to cause the issue. 

[Doc B.]

My guess would be a bad connection somewhere.