Share your Eureka! moment

[w1jim]

We’ve all been there - sometimes it’s something obvious and other times it’s something truly obscure. We’ll be working on something and getting nowhere and then all of a sudden - there it is - Eureka!

Now one persons impossible fix is another persons easy.

So share your moment.

 

[w1jim]

Here’s my Eureka! moment for today.
I’m fixing my friend Yuri’s Sansui AU20000 amp.
He said that intermittently the audio would get cruzzy in both channels. After a lot of searching and dead ends I found that the 65v positive feed wasn’t working. After replacing a bunch of parts I discovered that there was no continuity through one of the pins on the voltage stabilizer board.
I had fallen apart at it’s skinniest point.
Fortunately that particular plug had an unused connector in one slot; pulled it out and replaced the bad one.
Eureka!

 

[Poultrygeist]

This first pair of home-brew OB's with bass augmentation. Others have shared their moment on the long thread entitled "open baffle epiphany".

 

[Splatter Pak]

I was trying to fix a Charlie tuner that I had bought with other Sumo stuff - I called it a "short stack" as the power amp was missing. Nothing was working, so I did a close eyeball of the main board, looking for...something. After several minutes, there it was: some [expletive, deleted] had been in there ahead of me, and had soldered a capacitor in parallel with a diode. Eureka! I removed the cap, and replaced the diode for good measure. Then, it worked.

 

[Lavane]

I was trying to fix a Charlie tuner that I had bought with other Sumo stuff - I called it a "short stack" as the power amp was missing. Nothing was working, so I did a close eyeball of the main board, looking for...something. After several minutes, there it was: some [expletive, deleted] had been in there ahead of me, and had soldered a capacitor in parallel with a diode. Eureka! I removed the cap, and replaced the diode for good measure. Then, it worked.

I guess bypassing a diode with any random part will work as long as those electrons are flowing.

 

[kwayde]

Pulled My Kenwood KR-5150 off the shelf to give it a listen. Found the lamps were all very dim so I started checking circuit voltages. Found them to be about half of what they should be. Figured I'd start checking the transformer primary side, and when following one of the wires, I found it goes to the rear panel....to a switch....a switch I didn't even know was there. It got bumped over to 220v. That won't happen again.

 

[Lavane]

Pulled My Kenwood KR-5150 off the shelf to give it a listen. Found the lamps were all very dim so I started checking circuit voltages. Found them to be about half of what they should be. Figured I'd start checking the transformer primary side, and when following one of the wires, I found it goes to the rear panel....to a switch....a switch I didn't even know was there. It got bumped over to 220v. That won't happen again.

View attachment 2379366 View attachment 2379367

Nice hack. You would see that same kind of tab used on some equipment back then to keep that from happening. Just think what would have happened if you had 220v mains and your switch was flipped to 110v.

 

[titanstats]

I was trying to fix a Charlie tuner that I had bought with other Sumo stuff - I called it a "short stack" as the power amp was missing. Nothing was working, so I did a close eyeball of the main board, looking for...something. After several minutes, there it was: some [expletive, deleted] had been in there ahead of me, and had soldered a capacitor in parallel with a diode. Eureka! I removed the cap, and replaced the diode for good measure. Then, it worked.

What the heck, how did you even notice and why would someone have done that?

 

[kwayde]

Nice hack. You would see that same kind of tab used on some equipment back then to keep that from happening. Just think what would have happened if you had 220v mains and your switch was flipped to 110v.

I believe there was a tab at one time but it was removed. There is one at the other end on the rear for the pre/main switch.

 

[toddalin]

I have them all the time for my garden railroad where stuff is very limited.

For audio, I was proud that I had come up with a way to make a "random" selector for my A/B/X switch. That was a head scratcher and I don't think I've even seen a circuit for another.

BTW, I typically get mine between 2:00 and 4:00 AM.