NEED HELP on DX prs -I

[space2000]

hi,

i need help to understand the problem arised recently. i just made DX-precision I, last time it was ok, when i reconstruct my circuit, now i can play on low voltage without any problem like 22-0-22, but then i apply 56v on it , it's showing some problem like every few seconds making loud sound "chuik, chuik, what can cause this problem? i checked all transistors.

thank you
michael

 

[Nordic]

you didn't maybe leave the protection resistors in?

 

[space2000]

hi, thanks,

pls, which protechtion resister r u refring?

thank you again.

michael

 

[Nordic]

the resistors you install between PSU and amp during bias adjustment...

 

[space2000]

they are fine. nothigs is there.

 

[Nordic]

Next step is to check voltages...

Output side voltages
Regulated side voltages... measure from ground to zener/s.
voltages around other zeners...
output offset

 

[space2000]

ok, just checked, + rail side zinar to gnd 0.04v, - rail zinar to gnd 0.20v, output to speaker 0.002v.

 

[space2000]

sorry main voltage supply is 59.2 v

4.7v zinar to gnd voltage 0.44v, 12v zinar to gnd 0.08v

 

[Nordic]

Something is wrong!

What voltages are you useing for the regulator's zeners?

 

[space2000]

+ rail 2 zinars are 22v and 33v, 1 wats in series, same into - volt rail too. another zinar is 4.7v and 12v, one each, this are not in series.


i just connect as shown same as shmdt.

thanks for helping me.

 

[space2000]

sorry was a mistake.

sory there was a mistake in count taking.

main power is 59+ v dc, + rail zinar 22v in series with 33v ( found 53v), _ rail zinar ( found 57v). 4.7v zinar (48.4v). 12v zinar (12.2v).


now it is correct count taken. sorry for mistake.

 

[Nordic]

Feel R16 for overheating... also measure and make sure it is 10k

be carefull this resistor sees 110V over itself

 

[space2000]

yes, i checked this resister too its contaning 103.5v one side to another side. it is 10k but slightly gets hot in long run.

 

[space2000]

i checked transistors, all voltage from E-b are fine only BC547 E-B voltage is 0.197v. do you think it is correct volt for BC547?

thank you.

 

[Nordic]

negative....

What is the voltage from ground you get to the 22R resistor R19, on either side...? Also R18

 

[space2000]

hi,

from gnd to R18 and R19, voltage is same 57.5v.

 

[Nordic]

can you measure the voltages over them?

 

[space2000]

all are transistor E-B voltage....

Q6=0.620v, Q7=0.197v, Q9=0.606v, Q10=0.552v

 

[Mooly]

Hi space,
How many different amps have you got on the go.

 

[Nordic]

double check orientation of BC547 .. it should face te same way as Q9... maybe try replaceing this transistor...

Can i ask one of the mods to maybe merge this thread with Carlos's Precision I one thread...