In Yu-gi-oh! if a tuner monster's effect is negated, does it not become a tuner anymore?

No it does not. Skill drain only negate the effect of the tuner, but does not actually change the card itself. If u skill drain krebons, its attack negating effect will be negated, but u can still synchro with it.

However NOTE THIS that when u have a face down tune (beware of book of moons) u cannot synchro with that tuner. Similarly, if u have a face down non tuner, u cannot synchro with it

No, it stays as a tuner, just like when you negate the effect of an effect monster doesnt mean the monster no longer is an effect monster. because tuners can be both normal monsters and effect monsters. a good example is Flamvell guard or Tune Warrior

It still remains a tuner even if it's effect is negated so yes you can still synchro summon a monster.

A tuner monster is always going to be a tuner monster, so back to ur question yes you can still Syncro Summon a syncro monster

no, you can still use it for a sychro summon because it is not a effect monster if it was a normal tuner monster its because a tuner is just another new type not a effect

Tuner isn't an effect, it's a secondary type. There're even normal tuners.

Gladiator Beast conflict Chariot, stardust dragon, pollinessis, the forbidden chalice, the terrific one is Solemn Judgment, it wont negate effects in spite of the undeniable fact that it is going to negate the summoning of the monster earlier it could use its result.

there are many normal monster that is tuner. does it clear?

Not sure if that's correct

Good pertinent replies, thank you