Searching for a schematic dB Technologies OPERA 415 Lyric

[Donald218]

Having problem with above mentioned amplifier. +80VDc on bass speaker output.

Have measured the transistors but cant find any shortcircuits.

Best regards Donald

[nosaj]

Having problem with above mentioned amplifier. +80VDc on bass speaker output.

Have measured the transistors but cant find any shortcircuits.

Best regards Donald

Service manual link here, if you are not familar with the site down near the bottom you will see something that says processing wait a minute or so until it changes to download.

https://elektrotanya.com/db-technolo.../download.html
You are measuring with out a load correct? It is possible the LM3886 is shot.

nosaj

nosaj

[J M Fahey]

Sadly that schematic is misleading and quite incomplete.
1) It only shows the high frequency amplifier , based on an LM3886 and fed from +/- "LV" rails.
The supply is 4 rail so power amp works in Class H (F? G?) so +/-HV and +/- LV present, the second one feeding LM3886.

2) now transformer shows 30+30 and 60+60 VAC windings which is impossibly high, it woukld feed LM3886 some +/-42V DC which is IMPOSSIBLE, it would be most unreliable.

Yet you measure +80V on **woofer** amplifier out which is consistent with nominal +/- 84 V HV rails.

Just out of curiosity, please measure what is the actual voltage feeding LM3886 and post it here.

As of the Bass power amplifier, you are dead in the water, its schematic is NOT shown in the "official" service manual from Elektrotanya.

[nosaj]

My apologies Juan I'll notate that schematic as incomplete on my side. Great to see you here.

Hope the weather is well it's been close here.

nosaj

[dmeek]

I have these two. Maybe close enough.

https://music-electronics-forum.com/...1&d=1540139915

https://music-electronics-forum.com/...1&d=1540139915

[Donald218]

Sadly that schematic is misleading and quite incomplete.
1) It only shows the high frequency amplifier , based on an LM3886 and fed from +/- "LV" rails.
The supply is 4 rail so power amp works in Class H (F? G?) so +/-HV and +/- LV present, the second one feeding LM3886.

2) now transformer shows 30+30 and 60+60 VAC windings which is impossibly high, it woukld feed LM3886 some +/-42V DC which is IMPOSSIBLE, it would be most unreliable.

Yet you measure +80V on **woofer** amplifier out which is consistent with nominal +/- 84 V HV rails.

Just out of curiosity, please measure what is the actual voltage feeding LM3886 and post it here.

As of the Bass power amplifier, you are dead in the water, its schematic is NOT shown in the "official" service manual from Elektrotanya.

Thanks for your reply. The voltage on +LV on LM3886 is 39.9V Dc and this is correct according to schematic. Power out from rectifiers is +/- 84V DC on HV and +/- 40V DC from LV.

The bass power amplifier is shown In MKII schematic from DMEEK.

Regards Björn

[Donald218]

Thanks for your support. I am very confused, If I remove all transistors (Q1, Q2, MOS1 och Q7,Q8 och MOS2) I still have 37V DC measured between J3 och J4. This 37V DC i get from
D12 which I have changed. Could it be some kind off problem with earth from transformer?

Regards Björn

[J M Fahey]

My apologies Juan I'll notate that schematic as incomplete on my side. Great to see you here.

Hope the weather is well it's been close here.

nosaj

Thanks Nosaj.
I was not blaming YOU ... just stating that somebody uploaded an incomplete schematic and sadly not showing the area we need today.
Not blaming Elektrotanya either, they provide a great service !!!!

Maybe the full schematic is available somewhere else?
Or at least the power amp, which may be used in more than one model.

At least the 15" woofer is used at least in 8 other cabinets, powered and passive, even in a 2 x 15" Subwoofer, go figure, so why not the Power amp?

Oh, just see Dmeek uploaded 2 schematics ... we might get lucky

Ok, I´ll download them and see whether I can find something useful for the OP problem.

Do you *confirm* the latest upload matches your amp?
Simply to be certain we agree on parts numbers and such.

[J M Fahey]

Thanks for your support. I am very confused, If I remove all transistors (Q1, Q2, MOS1 och Q7,Q8 och MOS2) I still have 37V DC measured between J3 och J4. This 37V DC i get from
D12 which I have changed.

You might have put D12 the wrong way.
For now *remove* Q1/2/7/8 *and* D12/13 .

Could it be some kind off problem with earth from transformer?

No.

[Donald218]

Thanks Nosaj.
I was not blaming YOU ... just stating that somebody uploaded an incomplete schematic and sadly not showing the area we need today.
Not blaming Elektrotanya either, they provide a great service !!!!

Maybe the full schematic is available somewhere else?
Or at least the power amp, which may be used in more than one model.

At least the 15" woofer is used at least in 8 other cabinets, powered and passive, even in a 2 x 15" Subwoofer, go figure, so why not the Power amp?

Oh, just see Dmeek uploaded 2 schematics ... we might get lucky

Ok, I´ll download them and see whether I can find something useful for the OP problem.

Do you *confirm* the latest upload matches your amp?
Simply to be certain we agree on parts numbers and such.

Yes the MK2 schematic seems to be right.

Regards Björn

[Donald218]

You might have put D12 the wrong way.
For now *remove* Q1/2/7/8 *and* D12/13 .

No.

I have now checked , D12 is connected correctly and when I also remove D12/D13 I still got +37Vdc on J3/J4.
It´s very hard to see on the schematic which pins shouhd be connected togheter.