10 December 2017

Scott LK-72 - rebuild

What's happening.
I'm turning into one of those tube stereo geeks.
With the dark almost winter hours upon us,
instead of rushing home and working on a hot rod,
I look forward to sitting at our converted bar,
eyeglasses on,
maybe a drink - maybe not,
whittling away playing with wires and electrical stuff.
Strangely enough,
wiring a car isn't even my favorite thing to do.
I'm too picky and it's tedious,
but I'll do it,
and when everything works it's a big win.
This Scott LK-72 integrated amp 
was sold in the 60's as a kit.
A budget way for an electric geek to have tunes.
The factory wired model was the Scott 299C,
which had a gold face instead of poop brown.
Of course I ended up with a cheaper project...
Over the years electrolytic capacitors tend to dry up,
or in this case leak.
That's the tan powdery residue.
These are multi-caps,
can capacitors that are a compilation of values.
Post-war technology made this easier,
most likely a byproduct of all the WWII factories
that needed to continue churning out hi-tech chit.
There's two main methods to repair these.
Buy replacements if possible,
they are usually plastic wrapped black or blue,
and possibly a little different size 
needing different mounting clamps and holes.
The second way is way more fun.
Dig out the insides,
and replace them with new capacitors,
shaped like little batteries.
From the top everything looks original.
This involves grinding, fitting and thinking...
Like hot rodding but tiny.
Here there are ways to modify the ohm values,
online forums have high-priest geeks 
that give out loads of info.
For now I'm just a swapper.
Let's hear what new stock woulda sounded like.
Somehow that pile above equals this.
The roll of aluminum foil and electrolytic
is separated in 4 pieces.
These things basically are filter caps,
cleaning and storing the necessary power.
Trippy...
They call this silver box a toxic grenade.
It's a selenium rectifier that converts AC power to DC.
Supposedly not the best stuff to breath in
if it blows up.
Now swapped for a silicon bridge rectifier,
the black thing with the 4 prongs.
The suggested 1 amp replacement 
was smaller your pinky fingernail,
not much to solder fat wires too.
This is a bigger 4 amp version.
Now the tedious part,
replacing a bunch of single capacitors,
those white tube things.
I think there were at least 22.
Again replacements were much smaller,
with tolerances much tighter.
The tipping point...
Where's that drink now!!
Will it poof or perform?
After letting it run for hours on test speakers,
it was time to power up the Klipsch/JBL thumpers.
Oh yea...
Sweet sound,
without the overheating it had when first bought.
Next up was hammering out a quick shield.
Too much voltage and glass in there,
an accident waiting to happen.
Originally these came with a louvered sheetmetal box,
that seemed to collect too much heat.
The taller screen allows another geeky thing,
tube rolling.
This is dangerous as original Mullards, sylvanias
telefunkens and GE's etc can be $50-100 a piece!
Fortunately there are new east European versions,
much cheaper.
The main power tubes are 7591's,
made from a variety of manufacturers,
and sizes vary.
The original bottom RCA's were much shorter.
I screwed up and bought the larger ones on top,
but they (electro-harmonics) didn't fit.
We'd go with the center JJ tube,
and wow I can't complain with the sound.
The 12ax7's are the preamp tubes,
kinda the sorters that refine the sound.
Most say these are the most important,
as they can limit the gain or volume,
and their sound is amplified both good and bad.
There's a lot of info on the many variations.
I went with new sovtek 12ax7lps,
supposedly the best budget tube.
And check out these boxes!
Instead of adding a separate insulation wrap,
a 5th lead is folded in,
safely cradling the tube for shipment.
Cool!
Whew!!
I warned you it was geeky!!
You should read online forums,
there's diehard viewpoints about this tube stuff.
The amp had its time to shine,
and man it did.
However deep down I knew it was unfinished.
If you look at the 2nd pic,
there are 4 can capacitors,
and I only redid the obviously leaky 2,
although there are parts for all.
The third one went much quicker,
with a cleaner wiring trick for the ground.
I almost want to redo the first one.
For now my OCD stopped at the 4th one.
I'll have to mentally prepare for it later.
Let's wrap this up!!
Lastly taller feet were added,
more air should flow...
And a nicer faceplate was found.
The original had an annoying scratch.
The paint is sooo thin.
And here we are!
About an 80% rebuilt unit.
Are you ready for a holey chit yet?
Oh yeah...
A semi-matching tuner was on Craigslist,
but it was incomplete and a gamble.
I ended up flipping it which paid for the tubes.
Super stoked on the sound.
It's not as muddy or thick as before.
Not quite the warm sound people rave about,
but the Scott's weren't known for that.
They have a real uncolored sound,
like that's what it's supposed to sound like.
Yea geeky chit...
Thanks for reading!!
TP

05 December 2017

A day in the life... Toro 322 trim mower

Winter means going through
all the machines.
This is the one chance a year 
to get these reliable for next season.
This antique is a crucial part of fighting 
the weeds and grass,
specifically in the spots between the trees.
Sometimes the trees win.
You'd think a 1990 toro 322d,
almost 30 years old,
would be babied to last this long.
No.
The toro's are built strong but not too strong,
otherwise they'd never get replaced.
Interestingly there are 3 evolutions of this machine,
each seems to be made weaker than the other.
Luckily I'll take any excuse 
to get some cutting and welding in...
The scrap pile donated the perfect metal,
some 3/16" plate and fat rebar.
Way thicker then what these are built with.
There's a risk of making it too strong,
as somethings gotta give.
Well that'll give me or the next guy
something to do!
Looks like a beefy boat repair.
Good enough for years of thrash time.
This was the weak link,
the bracket that holds up the cutting deck.
Not even an inch thick spatter weld could hold it together.
Sometimes welding practice is better on scrap,
not something holding 3 rotating knives.
Probably why I fit in here.
After some grinding the crack was revealed.
Zip zip and as strong as new.
Now let's see how the guys trash this...
Besides going through the whole unit,
oil change, bearings and stuff,
a leaky hydraulic hose was also replaced.
That meant removing all the floorboard panels.
So yea this wasn't really a day in the life,
more like a couple days scattered over a week.
Now get to work guys no more excuses.
TP

01 December 2017

Making a little monster - Daihatsu hijet

Here at an enclosed city park,
we make optimal use of these little unregisterable off-road only trucks.
This daihatsu hijet was from a power plant
somewhere in Southern California.
This is the lemon twin in the fleet,
the other one is a workhorse,
this one doesn't like to run.
I found a problem with a fuel safety shutoff,
deemed necessary on the cab-over configuration. 
The wire had been twisted flush.
This little piece was impossible to find,
so surgery was required.
After digging down into the insulation,
a new wire was soldered on.
JB Weld has saved the day 
on similar tedious projects.
This trick got it running for now.
There's still an ignition issue I'll get too later.
Now that it could move on its own,
it was time to make some modifications.
Green daihatsu #3 had some good things to copy.
The scrap pile was raided for a solid bumper.
These have a hi/lo transaxle perfect for towing.
Brackets were whittled out,
and welded directly to the frame.
No bolts here.
I needed a welding project,
it had been a while and I missed basic metalwork.
More scrap for the tow hitch.
The ball threads were wasted,
so it was welded on solid.
Tip - 
U-haul won't rent you a trailer if your ball is welded!
Next up was this box of goodies,
an almost complete lift kit.
The rear used long spring shackles,
the front used spring spacers.
The new bumper was tested with the jackstands.
No problem.
The original shackles were a symmetrical design,
with a connected bolt.
So the fuel tank had to be dropped to removed.
Fortunately the new shackles slid on quickly.
The pinion angle wasn't changed much.
The before shot had a tail stagger look.
The after shot had the nice stink bug look.
Like a truck should.
The front was held up with a coil over shock,
or something like a McPherson strut.
The cup basically pushed it all down.
At first I didn't like the 2-piece design,
but it allowed a rough alignment with the slotted holes.
The brake line bracket had to be cut 
and welded at a different angle,
otherwise it was a quick bolt in.
This raised the whole truck over 2"!
Makes the tires look even tinier.
The green daihatsu has spacers and quad wheels.
I'm thinking of a dually rear wheel setup.
The only issue was the front camber is really angled,
more than this pic shows.
I've got a few ideas to fix,
but only one can be used.
More on that later.
This drove for about a week,
then it started acting up again.
I swear some things are lemons!
Anyway I'll update soon.
TP