The #2 BA-3K arrived TODAY

vigman

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WHY DO I GET THE ONES WITH BUGS IN EM???
First cockroach eggs from the Japan BA 3K
Now SPIDERS... all dead but EEEWWWWWWWWW

SO
Just a quickie
snapped power switch
1 blown Pre driver
It HAS been worked on in the past
It's the NEWER STYLE with the " connectors " for the bricks..
Details & pix to follow...

It's PLAY TIME
 
Great! Where is this one from? Looking forward to the pictures and progress reports as always.
 
Seattle Washington...
SO we are here.....
Front brick transistors OK..
Took the brick apart and am currently doing all the jumpers..
( bout 1/2 way thru )
There are (were) a LOT of weird fracture marks over the rivets.
And 2 looked REALLY suspect.
So tomorrow more fun and NUDIES...
Mike
 
And here we are

The protection circuit works.
The power relay is missing it's plastic case.
Power resistors have been changed.
Power supply & reg board seem to be OK.
The TO-3 style rectifiers were LOOSE along with most TO-220 hardware.
1 Driver board is playin grab a rail.
The other " seems " ok.
All feed thrus in the FWD brick done ( re assy this AM ) .
FWD brick Transistors were OK cept 1 gain was a bit off ( replaced ).

Geronimo
 

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Jeezus I hate spiders. One time I opened up a Sansui 212 turntable and got rushed at by a HUGE black thing. I almost squealed like a beearch. It had a whole setup going on in there, its smaller mate was also hanging around and there was also a big webby-egg thing. Bloody ghastly. I sprayed it all with flyspray and walked away for a couple of days.....
 
JoMark I'm confused
I do what is outlined in the factory service manual…
How can I help??
 
OK so Not all bad…
Some Not so good…

I did get the right channel to work, for about 5 minutes…
Lets just say I had a meter probe in my hand poking in a " sensitive area "… and the dog snuck up behind me.
Heath heard something that made him bark.. Heath's bark is REALLY LOUD ( guessing 98DB spl from under my chair ) and lets just say that probe got somewhere it shouldn't have been… POOF Scratch 1 2507 DAMNIT…. a LOT of the magic smoke was cast off from the factory resistors… and well let's just leave it at that..

Good news the " brick " is OK for that channel ( PHEW ) .
So I have taken 3+ hrs to start fixing the "OTHER" bad driver…
So without the 2 final transistors in ….. it now test's fine… and the transistors appear to be OK… 2 of the " fuse " resistors were outta spec by a bunch on the back 1/2.

SO now time to re goo and re install… plop em in shoo, the dog away & go for it…

I believe this will bring the right channel back… then start on the left.. Brick first…

So there you have it….
 
Mike you have a signal generator don't you?
Cause if you don't how do you adjust you power meters ?
So when you go to adjust them , after this procedure tell me if ca3k meters follow ba3k's meters in the output mode , ie when on -40db indication on ba3k , is it the same on ca3k ? like wise -30db , -20db , -10 db, 0db. All these provided you are using the volume control of ca3k.


Side note, ba3k pushes 170w or 0db when the input is 0,7v or 700mv @50kω @1khz and the level controls are full clockwise set.

Ca3k output is 1,3v , and that should be 0db also When the input signal is 130mv .
Correct?
 
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Some of the mysteries of the universe SOLVED!

New Rule #1…. never trust ANYTHING…
When redoing my 2nd driver board I was getting some STRANGE readings measuring things.. which caused me to pause & consider.
I thought it was my test leads… I made new ones up, still strange.
Used a 2nd meter PERFECT.. went back & did something SIMPLE..
And Lo and behold my trusty Fluke ( we had been together for at least 8 years ) was " acting up "… I pulled the meter apart, the connection for COMMON had broken SLIGHTLY loose ( swedge & solder connection ) 5 minutes later… like new…. PHEW~

And now DRUM ROLL…
After an ALL DAY & ALL nighter till 3am
Both channels are WORKING…
The final score ( to get to working status ).
Driver #1
8 resistors ,3 transistors and a LOT of touch up on the board.
Driver #2 ( the one the DOG made go POOF )
5 resistors, 4 transistors ,1 diode and board rework
Brick #1
1 transistor ( hfe was off by 25 compared to others )
Plus full feed thru rework.
Brick #2
1 WEIRD NTE sub and 1 shorted device ( both replaced )
Plus full feed thru rework.

Bias rough set ( and pretty stable ).
DC offset 0.00X
At this point I had all the parts to do the repairs ! YYEEEEESSSSSSSSSSSS

I still have to:
Get rid of my VD's 1212's
Pull the bricks back out & re good
Change meter lighs
Fix power switch ( broken shaft tip )
Start re cap process
Cal meters 1 has a 3db lag
Replace power relay ( or find a top.. which I MIGHT HAVE )

Cost to date… 450 GGGOOOOAAAAAALLLLLLLLLL :thmbsp:
 
VD's removed
Some recapping on 2507's and reg board…

Later today… heat sink goo N U

More parts on order
 
Did more re capping.... and got stuck.... for a bit.
I had some pick up work to do in the reg board.. the 2 10 uf@ 100 volt.and a few various single caps + fuse resistors.
The unit would power up, but not come out of protection with a -8 volt DC offset on the output!!!! I took the reg board out of the 100 volt 3K CLICK everything was HAPPY. I usually go for about 4-5 mods per board... test. Going back thru the mods...
after 45 minutes of WTF... I tested the originals I took out.. and they were OK...
And she's back alive... and I had 2 bad Nichicon caps OPEN.. I was stunned...
In other " work" 2512 board id recapped, and a couple more items on the 2507's.

I went for a little bit of a burn in... Some Supertramp @ 55 watts and ...well the amp sounds a bit ... compressed but I still have a bit more front end work ( Input board ) to freshen up...... It makes BIG POWER.. and runs cool... but not ready for prime time... yet
 
Yeah OOPS

So we are here today
Since I was a duffus on the preamp….and now with the CORRECT caps is the PS I have more bottom coming into the amp… ( amazing how that works LOL ) …

So still not there 100% but 50% better…
I really dislike the " factory " bulbs due to fading of the jel.. I cherry picked the best 6. Bias is holding with no wiggle and DC moved a BIT.

Still need to replace the 2507 trimmers and the 100uf bi polars PLUS rework the input board.. THEN load the new BIG PS caps.

I did a bit more clean up ( internal & external ) …
Today I'll just let her run…..

I think the pair I'll keep will be the Japan CA ( converter to 100 thru 240 )
AND this BA…. ( even though the Japan BA 3K sounds a bit better…. now )

Mike
 

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Hmmmmmmmmm

So JOMARK...
Remember that E bay listing for the BA 3K meters?
For the Japan BA-3K
Well guess what... They are for an AU-20K.. DO'H
Trying to deal with the seller.. but I have a feeling these will be in barter town soon...

They are very NEW....

Mike
 

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Progress...
Main power switch in.
Front panel washed & waxed.
Input board re caped, pots & switches cleaned.

Left to go....
4 caps ( waiting for parts )
Plastic cap for power relay
 
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