Paradise Builders

[brozatus]

Hello guys and a happy and healthy new year.

Yesterday I found a little time to try a first seating test in the enclosure,
I have taken 2 pics

[IMG][/IMG]



I beg you all to have a look at my posting #682, where I told of my 3 problems. I have no idea what to do to fix them.

I truly like to run my paradise,

regards,
Christoph

[PMA]

Christoph, if the layout you have shown is a MC preamp, it must have hum and buzz like a hell. MC preamp is one of the most difficult audio components regarding wiring, shielding, grounds, pickup of magnetic field from transformers. I hope someone who designed this project would also give some recommendations and construction hints. My hint is to keep the input of the MC preamp as far as possible from any transformer and avoid any loops (loops of analog ground).

[PierreQuiRoule]

For those who have Fairchild BC327 and BC337 devices, measurements below show they can be matched with devices from ON Semi purchased from Digikey. Now that this is done, it is time to return to my Paradise build.

hFE* (mV)	BC337-40 Fairchild NPN	BC337-40 ON Semi NPN	BC327-40 Fairchild PNP	BC327-40 ON Semi PNP
595-600				8
595-600				8
590-595				8
585-590				12
580-585				10
575-580				14
570-575				22
565-570				15
560-565				18
555-560				11
550-555				11
545-550	14			12
540-545	45			11
535-540	36			10
530-535	14			8
525-530	27			7
520-525	37			10
515-520	70			2
510-515	70
505-510	80
500-505	36		1
495-500	16
490-495
485-490			1
480-485			2
475-480			1
470-475			1
465-470			2
460-465		8	1
455-460		6	1
450-455		10	3
445-450		1	3
440-445		9	3
435-440		8	6
430-435		12	10
425-430		19	15
420-425		6	12
415-420		15	27
410-415		19	33
405-410		21	23
400-405		24	22
395-400		29	13
390-395			13
385-390			19
380-385			11
375-380			15
370-375			22
365-370			34
360-365			36
355-360			38

*hFE approximation using the circuit shown in Post #72. All measurements made at room temperature with fan blowing on transistor.

Happy New Year to all!
Pierre

[RCruz]

Originally Posted by brozatus

Hello guys and a happy and healthy new year.

Yesterday I found a little time to try a first seating test in the enclosure,
I have taken 2 pics

[IMG][/IMG]



I beg you all to have a look at my posting #682, where I told of my 3 problems. I have no idea what to do to fix them.

I truly like to run my paradise,

regards,
Christoph

Did you leave it connected for some time ?

Output offset should go down after caps settle.

[PMA]

Originally Posted by RCruz

Did you leave it connected for some time ?

Output offset should go down after caps settle.

Do they really need to to "settle"? I guess I have built hundreds of DC servos and caps never needed to "settle". They only needed to charge during RC time constant, this should last no more than seconds with max. like 10s.

[hesener]

Originally Posted by PMA

Do they really need to to "settle"? I guess I have built hundreds of DC servos and caps never needed to "settle". They only needed to charge during RC time constant, this should last no more than seconds with max. like 10s.

The "settling" that happens is the input caps (elcaps, connected in series with the cartridge and they have DC). It actually is like Ricardo is describing, let them settle (turned ON) for a couple weeks and see what happens

[chiily]

Just been putting together the first board of a Paradise brace and I'm having a couple of problems.

The power supply side is working fine, providing the +/-18V quite steadily.

I'm measured voltages at the test points as in the pdf for the schematic linked in this thread. The picture below (which may be a little large, but lots of detail!) shows the results.

Shame the text is too small



I firstly had a problem with a couple of solder bridges on transistors, I've highlighted those. I did power the board with the bridges in place so the transistors may be damaged. I removed the bridges, but not the transistors.

I misplaced a BC327 instead of a BC337 (Q51 I think - don't know my way around the board yet!). Again, I powered the board before I spotted the problem.

The problems I'm seeing are:

Output is at -10.9v

The EXT RIAA is at -12.5V

TP9/TP10 measure at -13V

Q22 (BC327) and Q18 (BC327) run very hot, can't touch for more than five secs.

Additionally:

TP5/TP6 measure at 16.5V
VCASCH is 14.4V
VCASCL is -14.4V

All three are inline with the published schematic.

I'm tempted to just replace all the transistors in the centre current sources, starting with the BC337, as that is where the voltages are incorrect.

Grateful for any hints and guidance

Thank you.

[hesener]

Originally Posted by brozatus

but I have ca. 5 V at pin 6 of the opa134 (should be around 0,5 V), on both of my boards.
Don't know how to fix this.

Christoph

thats not a big problem, it is the servo compensating the offset of the amplifier. 5V is high but still within the capabilities of the opamp. I would suggest to let it settle another two weeks turned ON and see what happens, eventually this voltage will come down or at least become stable.

[hesener]

Originally Posted by PMA

Christoph, if the layout you have shown is a MC preamp, it must have hum and buzz like a hell. MC preamp is one of the most difficult audio components regarding wiring, shielding, grounds, pickup of magnetic field from transformers. I hope someone who designed this project would also give some recommendations and construction hints. My hint is to keep the input of the MC preamp as far as possible from any transformer and avoid any loops (loops of analog ground).

PMA, your advice is good (as usual ).

Guys please check the assembly guide, it has my arrangement as an example, worked fine for me and is very low noise. I do use an external pre-regulator (as most of the builders are probably looking at doing anyway).

[PMA]

Originally Posted by hesener

The "settling" that happens is the input caps (elcaps, connected in series with the cartridge and they have DC). It actually is like Ricardo is describing, let them settle (turned ON) for a couple weeks and see what happens

Thank you for the explanation, anyway it is quite unhappy solution to put elcaps between the cartridge and input of electronic circuits. What is the reason, is there any input bias current flowing into input?? I would always try to avoid elcap coupling capacitors. Sorry to say that but this might be a serious design flaw here and look how the guys complain.