S*I*E*M*E*N*S V276 HELP NEEDED

[flaheu]

I've just bought two of them, i've connected them following this
http://audio.kubarth.com/rundfunk/getfile.cgi?f=%3D%2C3%24T%2CS4R.30R-U%5DV%2BW-I96UE%3BG-%3F%3DC%28W-BYG%3A68%60%0A
and this http://www.groupdiy.com/index.php?topic=1484&highlight=v276

one of them sound OK when i use unbalanced output (balanced output not used yet), for the connection i just unplug the 31 rear pins connector from the one that is OK and plug the connector to the second, for the second the level is very low and distorted a little and the gain is at 76DB !!!
Anyone an idea ? Do i have to recap them ? All components inside seems to be original parts (old part).
I'm getting frustrated, because the one that works sound fantastic, and i'd like to have a pair for stereo recording.

Cheers
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[martthie_08]

one of them sound OK when i use unbalanced output (balanced output not used yet), for the connection i just unplug the 31 rear pins connector from the one that is OK and plug the connector to the second, for the second the level is very low and distorted a little and the gain is at 76DB !!!

do you mean the frontpanel switch is set to 76dB and the output level is very low? Does the level change at all with changing the settings on the level switch or the fine adjustment pot? It might not hurt to try out the balanced outputs to see what you are getting there. Apart from that, did you

connect chassis, 0v and screen

???

If the electrolytic caps are all original, I'd replace them. This will change the sound of the units, be careful with your choice of caps, at least for those that are in the signal path. What kind of PSU are you using?

 

[flaheu]

HELLO martthie_08,

yes 0V is to chassis connected to screen.

If the electrolytic caps are all original, I'd replace them. This will change the sound of the units, be careful with your choice of caps, at least for those that are in the signal path. What kind of PSU are you using?

Can you help me to identify the electrolitycs in the schemo? What type of model do you recommend for replacing?
I'm using a small 1A Monacor 24V PSU.

Does the level change at all with changing the settings on the level switch or the fine adjustment pot?

Yes it's audible only if i put the fine adjust pot full CW and put the switch to 76DB

PS:
Oh and these 2 module's serial N° are very close, about 8 N° difference.

Cheers, hope you can help me

 

[martthie_08]

Can you help me to identify the electrolitycs in the schemo?

I am not really sure if I can identify them from the schematic, I'd assume that they are the capacitors with one white bar and one black bar, like C1 for example, although some of those might also be film caps. The ones with two black bars, like C9, are in the pico range, so they might be tantalums. Maybe someone with more experience can verify this, I'm just guessing! But it is easiest if you open the unit and look for the electrolytics - they are easy to identify by sight.

What type of model do you recommend for replacing?

depends on where you are located, please provide your location in your profile. If in the US I'd give Nichicon a try, they are hard to get in Germany. I had good luck with Panasonic for PSU caps and Elna for signal path caps. But it also depends on how much space you have inside the unit and whether you need axial or radial types.

I'm using a small 1A Monacor 24V PSU.

Interesting, I had never seen those with more than 12V or 15V for DC output, which model number do you have?

Oh and these 2 module's serial N° are very close, about 8 N° difference.

That must not have much meaning, I have two V72 that are pretty close in their serial numbers that sound quite different, not usable for stereo. But those are tube units, so it's not really comparable.

 

[flaheu]

hey martthie-08,

I've tried with the balanced output, the problem still occurs.

I think i'll recap this preamp and will see.....
If you have any idea... don't hesitate

I'm using a small 1A Monacor 24V PSU.


Interesting, I had never seen those with more than 12V or 15V for DC output, which model number do you have?

It appears to be a 15vdc modded to 24V.

 

[Twist Turner]

clean all the connections between the circuit boards. There are circuit boards coming up the sides with gold plated connectors sometimes in transit these get tossed around and don't make so good connections anymore.

 

[martthie_08]

on the schematic, there are some voltages drawn in, maybe you can verify those with a meter and get some idea in what area of the circuit you problems are. Let us know how things turn out and good luck!

 

[flaheu]

OK guys, thanks for your support. :thumb: :thumb: :thumb:

Is somebody having a control protocol or something similar to know where to put my meter ?



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