Nakamichi CA7 Schematics ?

[MadMutt]

Hi all, Trying to find a schematic of the Nakamichi CA7 Pre amp.

Thanks......
MM

[Shaun]

Hi MadMutt

I, too have a CA7, requiring repairs to the balance control. If you do find a schematic, would you be so kind as to send me a copy?

[tvi]

I have a average pdf copy of the schematic.
Email addresses and I send it to you

Regards
James

[MadMutt]

Shaun - Yup same here.
Ended up replacing the balance control completely.
Used an Alps centre detent pot part number 697-928.
Final cost inc our gst and freight came to Au$74.21.
Will post some pics soon for you.
Only hitch was that the shaft on the replacement wasn't the length stated on the site.
I cut the extra needed off the original, cut a slot into the back of this 'extension', and then used two part epoxy to glue them together.
Works just fine, Customer VERY happy.


Tvi - Ta, email is -
f0rum5 at tpg dot com dot au
- note that first word has two numbers in it, a zero and a five.

[MadMutt]

Pics of the mod for those interested.

Remove ALL resitors under the balance control.
Short across R178 and R278.
Connect new pot using short wires.

(yes I realise I could've done it with less wires, but to me this looked neatest).

[MadMutt]

And a pic of the topside.......

[Shaun]

Hi MadMutt

Thanks for the info. I had bypassed the balance control, but that caused the 3-way tone controls to malfunction, so I have the tone control bypass function permanently selected.

Who did you buy the pot from?

[MadMutt]

Oops sorry, Farnells.

Hope it helps.......

[Shaun]

Thanks

Hey, it must have been fun taking out that switch!

[MadMutt]

Quite easy really.

Owner/friend previously complained about crackling, so I had already sprayed it with progold (Caig labs) lasted for almost 2 years.
He started complaining again so I suggested he disassemble and spray himself.
He tried to cheat and not pull the front off to remove the black plastic cover, he ended up cracking 2 wafers.

So back it came for me to replace it.

Remove all knobs (not the volume one).
remove top and bottom covers.
remove front extrusion (watch for wire near left side).
remove front circuit board (only need to unscrew so it can be moved a bit).
undo volume control flexi joint (small allen key).
unbolt front sub panel (dont forget the control shaft nuts).

This allows you to move the front sub panel foward enough so that once the control is unsoldered it can be removed.

Forgot to mention, if you want the best for the unit, while its apart,
I also recomend replacing the opto couplers (look like white i.c.'s).
Their cheap and make quite an improvement to the overall sound of the unit.

Can't remember, but if theirs a memory batt/cap it will be crying out to be replaced by now too.

that should keep you busy for a day.