problem with PG MS2125

[zio]

Hello

I'm fixing the phoenix gold MS2125.
It's an old grey series model rev-c. , but not the very first

I replaced the power mosfet burned a DC/DC converter.
I found strange things, a cap 10000mF with the negative not connected.

Now everything goes on, but I have 2 problems.

1) main tension between the two amplifiers is different
2) on R/C filter after the transformer warms too.


1) a channel has a power on final 36 + 36 volts.
the other channel has 39.5 + 39.5 volts.

Now, looking for the problem, I checked on the secondary circuit,
formed by 4n35 + zenner + zenner + 510hom.

In the channel that has 36 + 36volt,
about d320 , measured 33 volts , mod. 1n5257
about d326, measured 36,5 volts , mod. 1n5258b
by summing the tensions on zenner and fall on 4n35 and resistance, you get total 72.6 volts.

In the channel that has 39,5 + 39,5 volt,
about d308 , measured 39,1 volts , mod. ???? No one reads
about d325, measured 33 volts , mod. ???? No one reads
by summing the tensions on zenner and fall on 4n35 and resistance, you get total 78.1 volts.

I checked the operation of 4n53, bypassing one zenner.
everything ok.

in the model most recent are the zenner. 1n5258 + 1n5259
But this means raising the tension:

1n5258 = 36V
1n5259 = 39v
Summing optocoupler turns to 36 + 39 + V on 510(about 1V) + 1V opto = 77 Volt
I don't understand.


2) all filters R/C warm too: smoke

R335-R342 240Hom1W
01mF C337-C344.

the new templates are 470Hom and. 001. can I replace without problems?


Sorry for the language.
I used a translator software.

Thanks to all

[1moreamp]

R335-R342 240Hom1W should be 470 ohm 1 watt
01mF C337-C344. should be .001

Other diode RC are 91 ohm 2 watt and .001 caps

These are the RC nets across the secondary diodes of both supplies


about d320 , measured 33 volts , mod. 1n5257 < should be 1N5258B 36 volt
about d326, measured 36,5 volts , mod. 1n5258b < should be 1N5259B 39 volt

Rails should be +&- 15, +&- 36 @ fuses, and +&- 42 @ drivers stages


Hope this helps some anymore questions just post them here, and please delete your other post that is duplicated of this one, thanks...

[zio]

Thank you.

you know the volt on pin 1 and 2 of the sg2525?

Thank you



I wrote to administrator, because I can't delete the post duplicates.

[1moreamp]

Originally Posted by zio

Thank you.

you know the volt on pin 1 and 2 of the sg2525?

Thank you

.

Not off hand, what symptoms are you experiencing ?
pin 1 of SG2525 U1 is triggered by opto OP300 and Sg2525 U2 by OP301 output that use the zeners mentioned before in the earlier post. Are you having regulation related issues, or shutdown on start up issues ?
Opto 300 and 301 should get switched on by proper output rails as defined by the dual zeners on the supply secondary. Both pin 1's are pulled to ground by 330 ohm resistors without any signal from the opto output.

What other issues/symptoms are you experiencing ?

[pergo]

hi zio,

the answers in acs forum are wrong..a lot

[1moreamp]

Originally Posted by pergo

hi zio,

the answers in acs forum are wrong..a lot

[zio]

Thanks pergo. I realized

[zio]

all solved.
The problem was generated from cells RC, R335-R342, C337-C344


I replaced it, as suggested by 1 moreamp. Thank you.


Still a doubt.
I checked the zenner near 4n35.
are 1n5257b + 1n5258b.
the power on final is 39 + 39 volts.
If i replaced with 1N5258B + 1N5259B, should I switch to 41.5 + 41.5 volts.
What do you think?

[1moreamp]

Rails should be +&- 15, +&- 36 @ fuses, and +&- 42 @ drivers stages

Glad top be of help....