Ca-3000 #2 Rinkya " deal "

After much testing, listening, looking,probing... here is the deal....
The ballistics on the right are slower than the left.
Steady state tone 200~10K they match within a 10th.
BUT get some percussive stuff going on.. and the right seems LOW by eye.
Measuring on the sencore PA-81 ( which has REALLY slow avg meters ) they match with no deviation. So I have some recapping to do in the meter drivers. If memory serves this was a problem in the OTHER CA-3K that was missing a channel of metering....
 
That's ALOT in 1 sitting

If you look up a few posts your see the before on the filter board…
And NOW the AFTER… tada…….
All molex's on filter done…
BUT I'm short 2 1uf NP's
Everything else on there is recapped
All jumper wires in the BIN!

Interesting observation.. i THINK… this unit MIGHT have had factory jumpers between the top and bottom of the board.. This work is the same on the input board.
The jumpers SEEM to be a busted up DB-25 ( male ) and the pins cut, used as jumpers.

Everything WORKED on the first go round ( PHEW ).. And passes the reflex hammer test. ( roughly translated swipe a reflex hammer from your HMO.. once work is done whap the board in many area's .. if the audio breaks up you have a cold solder joint to loose connection ). All 100% SOLID and got rid of a tiny DC thunk when engaging one of the filters.

So I need to order some caps… The unit is just barely bolted together to operate safely.. Plus I need to pull the filter board again to get the meter drivers out….
 

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Good news, Bad News!
So I went in last night and started the meter board.
Replaced all the 10uf 47uf VD1212 but again I was shy the 1uf NP's
Good news:
The meter cal point didn't change and both the meters are MUCH faster in tracking, but a few 10th's different, so that's a twist the pot , no big deal.
BAD NEWS
When the top meter select button is depressed ( 40db pad, Input ) the meters just sit there @ -30 and wiggle a few 10th's GAH!
The meters work fine in the other 2 mode's "0" and output
the problem is the same for both L & R

It was late….
Seems like I have an air gap in the wiring for that function… now.

Getting coffee and going back in….
 
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Ok this is WEIRD…
in the feedback loop of the meter drivers are 2 VD 1212's..DO-01 thru 04. Which I promptly subbed for the back to back In4148's .
Well guess what DON'T DO THAT!
The extra lead length of stacking 2 diodes causes the output to go NUTS.
Now to make SURE I wasn't on some magic mushrooms slipped into my pizza… I looked at pin 6 and it was SCREAMING @ 50K ergo causing the ~-30 reading on input …
I took the diodes out ( 1N4148 pair ) and put the VD's back in … PURRRRFECT….
Whipped up a new pair of diodes put em in 1 side and ~-40
So I'm leaving the VD's in … god knows I have enough SPARES..
And yes I could have come up with a C value to roll off the meter amp bandwidth … but hey.. If it ain't broke…..
I'm not QUITE sure WHY this get's unstable… but it really REALLY does… Moving on~
 
That's strange behaviour . I wonder why?
But on the other hand , take into consideration the extra low voltage required to calibrate the meters for the -40db position, only 1,3mv. MC cartridges pump that low voltage out.
 
The whole circuit is a bit odd.... the 2 diodes are a hard clipper... and your trying to drive an AC square wave... prior to the bridge internal in the VU meter... it's not just a straight buffer... and there is a SHITPILE of gain in that amp...It's not just a straight unity gain buffer....
 
And NOW 8 caps away from finish

8 1uf NP's and were done like dinner, well as far as the electronics are concerned…. Starting @ 1:00am PST I did the input board, which was the last board to recap.. TADA.

Did all the touch up, cold joints etc…
and just on HP's there is a marked difference in audio… a bit SMOOTHER…..

I did have to re clean some of the molex pins… Just little OCD stuff.
the internal ground wires were a bit funky.

I ran out of the 1mm nylon tubing ( wahhhhhhh ).
My kingdom for a clean back panel…..
 

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Not much to report....
Final caps came in
Aussie tubing came in
Couldn't do much today since we had ANOTHER "Planned Power outage ".....

SOON....VERY SOON
 
Mike,
"SMOOTHER....", worth all the pain. Well done. Just spotted the 1mm tube arriving. You will still have another 70meters to use up !.
 
_Mano
This roll is not QUITE the same as the stuff I got from you.. It's solid core and a bit thinner… Not " bad" just different… ( and with shipping and all that REALLY expensive )
I'm not bitching… just the cost of doing the hobby!
 
The last caps went in last night…. and it was captivating… on final " test".
Made a few OOPSIES, lifted a trace on the meter board, a molex popped off and had me chasing my tail for 10 min ( lost right channel ) . Started using the new lacing cord and I think it's the same size as original and looks good. BUT when trying to cinch a bigger bundle it's a bit to stretchy.. So now today is listening and final measurements.
 
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