Need DB Technologies SUB 05 or SUB 12 subwoofer amplifier schematic

[mariuss77]

Hi to all, i'm new here so i hope i posted in the right section...

I have recently purchased an used DB Technologies SUB 05 subwoofer, with a blown up amplifier stage.
The ex owner did tried to repair it by himself without any electronics knowledge and all he did was to remove the mosfets with a good part of traces.
Also he did managed to loose all the mosfets and he also doesn't remind what they was.

I have searched the net past days without success a schematic for this particular sub and i hope someone here will have that schematic and share with me helping me that way to repair my sub.

Thanks!

[izzzzzz6]

Hi, i also have a Db technologies sub 05 with a blown amp, what is the problem with yours? Perhaps we can work together to solve this.
James

[mariuss77]

Hi James,
On my sub the amplifier lacks all the mosfets from the final stage, they are in two pairs, 2 with 3 legs and 2 with 5 legs and i don't know what they are, maybe you could take a look at yours and take a picture or a note on what is marked on them.
If there is something you want to know please ask.
Cheers!

[izzzzzz6]

Ok i will take a look at it for you next time i go to my lockup. I can't remember what my one was doing, i think the protection light was on and no response from the amplifier, but i don't know why. I didn't test any of the components yet.
James

[paleeman]

Hi Mariuss77

The parts you're looking for are: IRFP140 & IRFP9140, SAP16N & SAP16P. For some reference, you can use the RCF ART 315 schematic. (already been posted, you can find it here, on this forum)

Good luck.

[g1]

Here's the ART315 amp schematic:

[Jazz P Bass]

If the SAP16's are blown or missing, you will need to replace them with STD03N & STD03P as the SAP's are not available.
That's the good news, as the STD's are available.
The bad news is that you need to mount an external emitter resistor (0.22 or 0.33ohm/5 watt) on each one.

[paleeman]

That is, unfortunately, true. Sometimes, it is a major pain, to find an adequate place for the external emitter resistors.
But if you look on the bright side, you can still find some SAP's on ebay. (pretty expensive, though)

[mariuss77]

Whoa! Thanks guys for the great replies, now we are talking!
Next week i will search for components, hope to find them on local radioshack.
@ Jazz, what you mean by bad news? i see that is plenty of room for 2pcs./5w resistors, or am i missing something?
Btw, you are very nice to share that.
I will keep you updated after purchase and install the mosfets, hope there will not be any other issues
Cheers!

[izzzzzz6]

Adding resistors to alternative fets

If the SAP16's are blown or missing, you will need to replace them with STD03N & STD03P as the SAP's are not available.
That's the good news, as the STD's are available.
The bad news is that you need to mount an external emitter resistor (0.22 or 0.33ohm/5 watt) on each one.

Hi there Jazz P Bass. I have read here that if using the alternative transistors (STD03N & STD03P) then external emitter resistor (0.22 or 0.33ohm/5 watt)needs to be added to each transistor, i assume one leg go's to the emitter, where would the other leg solder to? The Base? Sorry my knowledge of how exactly transistors work is a bit limited. Could anyone elaborate or does someone know of a link to a thread which explains this in more detail? Thanks.
James

[Jazz P Bass]

The Sanken SAP16 transistor had an emitter resistor on it's output pin, built in to the transistor.

The replacement, STD03, does not have this feature.
So one must add the emitter resistor to the existing circuit.

The emitter resistor (or more commonly, the 'ballast' resistor) generally goes to the speaker out.

[The Dude]

Just tossing this out there. Firstly you don't need to explain the risk of buying what might be fakes to me. I'm well aware of potential problems. That said, I recently repaired an amp that used the SAP's and got a pair from here:

1pairs Transistor Sanken to 3PL 5 SAP16NY SAP16PY SAP16N SAP16P | eBay

I installed them and ran the amp for several days to be sure the parts could be trusted. I had no problems. This was months ago and I have not seen the amp come back.

Edit: Also, the price is right and they didn't take too long to arrive.

[mariuss77]

@Jazz , thanks for clarifications, i did some research about and i find out that the resistor blows before the junction and thus being responsible for the part replacement with STD's.
After this i am aware and more biased to work with STD's instead of SAP's even if that needs the external resistor.

@ The Dude, thanks for feedback and link, Tuesday i will search in local market for STD's/SAP's and in my pile of late 90's home amplifiers, some of them very powerful discrete amps. The SAP16 look very familiar to me and i might saw them in one or two of these amps, maybe i get lucky.

Cheers!

[g1]

i did some research about and i find out that the resistor blows before the junction and thus being responsible for the part replacement with STD's.

In these cases where just the internal resistor is blown, but the junctions are still good, you can just install an external emitter resistor. No need to replace the transistor unless it is shorted.

[paleeman]

In these cases where just the internal resistor is blown, but the junctions are still good, you can just install an external emitter resistor. No need to replace the transistor unless it is shorted.

Yes, g-one, in some cases it is enough to insert an external resistor between pins S and E. But in most cases, when the 0R22 fails, the 100R resistor, for current sensing, goes with it, as well. (By my experience, at least). So it would work, but would not have current limit feature.