neutrik tt402a , reading 20db low

[NorfolkDaveUK]

Hey all hope you are all well, I have an issue with a neutrik tt402a I recently bought , I'm a reel to reel tech for the most part so , this will come in very handy if I can make it work well. I'm using a ferrograph RTS 2 and APU combo at the moment . So here's the story .

I bought it on eBay and it was filthy , and the case was battered but inside is was pretty much mint. , I have recapped the power supply , and a few other board , i.e. the meter driver board , the gain chain etc , and here's where I'm at . So when I bought it it would read freq perfectly , but wouldn't read amplitude at all , I traced that to a problem on the "spare filter" board and on removal of that , it brought back the ability to read amplitude , however , its reading it 20db low . So if I feed 0dbm (775) from my rts into it , it reads it as -20dbm , likewise if I send a signal from the tt402a to the rts , it will read 0dbm on the rts and -20db on the tt402a .

Now here is the problem , this thing is very rare , I can't find a schematic for it anywhere , believe me I have hunted and hunted , and there is nothing , I contacted neutrik , no reply  . So , I have no clue really other than my reasonable knowledge of electronics and audio gear / logic . If anyone has any idea what's going on here or where I might gets some hints as tomhow to put this right I would be very very grateful .

Thanks in advance guys and happy sparking !!

[calibrationfixture]

Hi NorfolkDaveUK,

Around Februar in the coming year I have to service a Neutrik TT-402(A?). It has a full set of Manuals. Thus a little patience (Owner is on Holiday for quite a while).

Calibrationfixture

[707dave]

Hi,
I'd also be greatful for any information you can supply from these manuals - are you hoping to scan them?
My unit is misbehaving - the distortion filter is not auto tracking.

Regards
David

[fredswed]

Necroposting to announce that I have scanned and published a set of manuals for the MJS401D / Neutrik TP401/TT402(A).

There is a complete, scanned service manual for the MJS401D / Neutrik TP401 available.
I have also collected bits and pieces from other sources and organized them for the TT402 and TT402A models, as applicable. Mostly schematics but also a few sections from the service manual and the IEEE-488 remote control manual.

Downloads and a brief history/timeline can now be found at https://viklund.se/electronics/neutrik-test-set/

If anyone has the service manuals (text parts) for the Neutrik TT402(A) please reach out to me.