Fuse question, wire question and some rambling ...

Laudanum · 1054

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Offline Laudanum

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on: October 31, 2020, 12:05:30 PM
If it ain't broke, don't fix it.   I should really stick to that but ... I don't.   I have an ALPS RK27 installed in Speedballed Crack.  Wiring was direct to the pins of the pot.  Has worked fine for 8 years.  I didn't even realize those little RK27 boards existed until I found a thread here a little while back.   I picked up a small enough PCB to avoid having to cut a groove on the inside of the wooden base (or so I thought).  So yesterday, out of sheer boredom, I decided to wire up that ALPS pot the "right" way.  Figured it would be a fun little project.  This required replacing some wires to and from the pot as the existing wires were too short to reach.   To access all the wiring I had to unscrew the Speedball boards and move them out of the way.   No problem, a couple hours taking my time and I should be done ...  WRONG.  Did the desoldering, soldered in the new wires, soldered the pot on the board and got ready to buttoned it all up.  The PCB is a hair too wide.  I eyeballed it and was confident that I was good to go but I was wrong (as usual).  2 choices, Dremel a small groove inside the wood base or start all over and go back to wiring direct to the RK27 pins.  The latter wasn't happening again so reluctantly, I choose the former.  In the end, grooving the inside of the base was not a big deal.  Worked out quite well and you can't see it from the outside. 

 At any rate, I get everything buttoned up and I'm feeling good to go ... LEFT CHANNEL IS DEAD.  Go to troubleshoot and two LED's on the big board are out.  I quickly notice a wire that broke.  Desolder the broken wire from the big board.  Unscrew the big board (again), get one of the big film caps out of the way to access the solder terminal where the wire broke.  Replace the wire from there to big board.  Button it back up (again) and just to be sure this time, did voltage checks.  All checkd out, should be back in business.  Thankfully, I was back in business.  Took a lot longer than the couple hours of busy time I thought it was going to be and turned out to be more of a hassle than the fun little project that I thought it would be.  Moral of the story ... if it ain't broke, don't fix it.   One day I'll pay attention to that idiom. 

At any rate ...

Fuse question.  1 amp slow-blow or fast acting?   I have a fast acting in there now but thought I read where Doc suggested a slo blow.

Wiring question.  Rather than braid a new trio of wires from the RCA inputs to the pot, I used a section of Belden 8450.  The 8450 was used all throughout the Foreplay III so I figured it should work fine here.    I didn't do any critical listening since the re-work but nothing struck me as sounding any different with some casual listening last night.  Anyone see a reason why the 8450 would be a poor choice compared to the 3 wire braid? 

Thanks 
« Last Edit: November 01, 2020, 11:10:54 AM by Laudanum »

Desmond G.


Offline Paul Birkeland

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Reply #1 on: October 31, 2020, 01:10:06 PM
A 1A fast fuse should work just fine.  The 8450 will also work fine, but we try to keep the Crack as simple as possible to make it easy to build for first time builders. This means nothing beyond single core jacketed wire.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Paul Joppa

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Reply #2 on: October 31, 2020, 08:10:14 PM
Classic story!

We once thought we'd pull off the old wallpaper on a weekend so we could paint the living room walls. Twelve layers down, we discover that the paper was holding the broken plaster together, so down it all came, along with the ancient lath. This exposed the knob and tube wiring, better get that updated before we button it back up. And hey - while the electrician is here, the old power entry box is a mess, ... yeah, that weekend lasted about 18 months.

Paul Joppa