so i now know that there's a gamma turn, alpha turn, epsilon turn and beta? (the beta is a joke i added)
how do they compare?

one is faster than the other.
i believe it was gamma that is faster.
but you just really want turning in general

All I know is that the one in the D604 is a lot more flimsy than the one in the D503. The one in the 503 is a lot cooler to watch too.

I think it all depends on how they turn as to what the name is. One spins the laser diode so that it is then facing down. Another has the diode do sort of a loop on a "U" track so that it is facing down. The spinning version get it done faster.

well, here are some videos of the turns.
the first one is the older style of tuning that was on my first CLD-3070 player.



But this has some more moving parts than mine did.

good but slower than the other style.

this video says it's a gamma turn:



from what i read on the internet players with the Epsilon and are on a U track to go even faster.
i know my CLD-R7G is on a U track but i always thought it was Gamma turning.

anyway the difference between the 3070 and the R7G is something like 6 or 8 seconds shorter
so if you can't find or can't spend more on a faster turning just get any turner.

i was always happy with that 3070 but i am happier with the R7G

Besides one being faster then the other......is one turner more better in regards to repair breakdowns issues?

because the cld-97 has the alpha turn

i've never heard of one breaking more than the other, it's just speed.
some are faster than others.

The U track one in the 604 is all plastic and definitely seems to have more problems. I'm sure the "m holder" will be one of the parts Pioneer runs out of sooner rather than later. The entire mechanism is plastic, its one of the later designs and is supposedly faster. The twisting style in my 503 has more cast aluminum parts and probably lasts longer.

i'm liking the look of the late-80's Alpha mech best, YMMV; slow, but exceptionally well built...

Only 10 years later, I finally asked my self what the different in A-B turn were... one never stops learning.

ALPHA Turn



FLIP Turn (my description) -- early SONY reversing pickup


GAMMA Turn




EPSILON Turn


C-QUICK Reverse (SONY) similar to EPSILON


Pioneer LD-W1 (and clones) 4-sided players with a single optical block


The whole channel is actually quite random and interesting!

https://www.youtube.com/@Watcher3223/videos

Julien

You need an LD-W1 animation in there. It’s based on the earliest mech but obviously has key differences.

Good point! Added above.
This is so massive it reminds me of a large boat capsizing...

Which made me wonder if the earlier models "shipping screw" was related to specific types of turning mechanisms or if the newer models had a locking mechanism that didn't require a shipping screw.

Julien

I only recall the 1st & 2nd gen Alpha’s and the LD-W1 needing a transport screw.

I could only guess that the reason the Gamma & Epsilon designs did not need a transport screw might be a combination of being more durable for transport as well as being lighter weight machines.

The "transport screw" as it was labeled or "shipping screw" as you called the actual function held the alpha turn mechanism in place so it didn't get knocked out of side A position for shipping. None of these had anything to do with holding the laser during shipment. Off the top of my head I'm trying to remember if the very early diode lasers had screws holding the laser. This was a must for the older tube laser designs.