How does this construction work?

Question

For full context, see here: https://www.docdroid.net/XIK9pCk/img-20171020-0001-new.pdf#page=2

The sentence in question is taken from the very last two lines on page 2 of the PDF: ええ、ありますね。かならずしもうるさいチャイムやベルのおかげだとは思いませんけど。

I think that the person here basically wants to say

"because of the chime and announcement, I don't always do not think it is annoying."

My biggest problem though is that おかげで/おかげだ is used. I just learned in my textbook that this is used when CAUSE X has lead to POSITIVE RESULT Y. I get that the speaker, in case I understood this correctly, wants to conceal his/her negative opinion. But I feel very very unsure about this interpretation of mine ^^ Since I learned that おかげで/だ is used in positive contexts, I fear that it won't possible to use it inside a negative statement, unless irony is at play here. But I've no experience with irony in japanese so far...^^

Here's my full translation: (Very literal) "Yes. It sure is. But I do not always not think that (="that" due to と思います) because annoying chime and announcement."

(more paraphrasing) "Yes. It sure is. But I do not always not think so (= "I sometimes don't think of it in its function as a safety measure" see the pretext) due to the annoying chime and announcements."

I couldn't find a way to integrate the THAT in "I think that...". It never works because the clause it relates to is a causal clause at the same time. At least if I understood おかげで/だ correctly.

Answer 1

You have to look on the context, what she is actually talking about. This is given by the question asked to her in the sentence before.

チャイム？あっ、発車ベルのことですね。少しうるさいところもあるかもしれませんが、日本の乗り物には安全性があると思いませんか？

ええ、ありますね。必ずしもうるさいチャイムやアナウンスのおかげだとは思いませんけど。

Translating gives: Chime? Ah, the departure bell. It might have the property of (ところ, here could refer both to physical places, or to more abstract "places", that is "parts"/"properties" of the chime itself) being a bit loud, but don't you think that there is safety (meaning safety is good, in Japanese you literally say there is a property of safety, 安全=safety, 性=property, ある=there is) in Japanese transportation?

Yea, there is. But I do not necessarily think it is (only) thanks to the loud chimes or announcements.

As you can see, the answer refers to the question regarding safety in Japanese transportation.

Let's split the sentence up: 必ずしもうるさいチャイムやアナウンスのおかげだとは思いませんけど。

=>

1 必ずしも - not necessarily

2 うるさいチャイムやアナウンスのおかげ - thanks to loud chime/announcement

3 だとは - topic marker

4 思いません - do not think

5 けど - but

5 and 4 should be straight forward, gives the start of the sentence in English: But, I do not think

Next, 3 comes directly after 2, meaning that 2 is the topic of the sentence, which we understand must be an object. If we for a moment ignore 1, we thus have the sentence: But, I do not think thanks to the chime

What we are missing is the context. Since we were just asked a question we know what the context is: there is safety in Japanese transportation, if we denote this as "it" as one does in English, contrary to Japanese where it is just implied, we thus get: But, I do not think it is thanks to the chime

The last part is to add the "uncertainty" 1 (not necessarily) in the sentence, => But, I do not necessarily think it is thanks to the chime

The phrase 必ずしも ｡｡｡ V~ない comes in this form, such that the sentence opens with "not necessarily" and then ends with a negative verb to which it is connected.

EDIT I would also like to point out that there is no actual double negation in the sentence. 必ずしも is used in negative contexts and that is probably why the translation of it adds a "not", but the actual negation will come from the verb in the sentence.