Wharfedale Titan 12 Active power supply problem?

[diydidi]

I much prefer working on the "A" models than the "D" models. I have found in some cases on the "D" models, the DSP board can also go bad.
Many people have been complaining about the "D"s. If for instance you play music through them from your laptop, or whatever, between songs the speaker goes into some sort of audio off mode. then when the next song starts off very soft, like a piano intro or so, it takes a while for the speaker to kick back on. You might not hear the first note of the song because of the time delay. Almost like a noise gate. Stupid design!!
Wharfedale say they don't have a mod/fix for this...blah bla blah

[diydidi]

Ive rebuilt a 3 of these Class D driver boards. Replaced all semiconductors. Plays fine until a certain volume is reached then shuts down.
Now, I'm thinking, is there a difference between the IRS2011 and IR2011??
The originals use the IR2011.
Maybe Paleeman can chip-in here and confirm.

[Jazz P Bass]

Here is an App Note from IRF on the differences.
(at first glance, the changes seem to be minimal.)
(at least nothing jumps out as 'this will not work'.)

As a matter of record, I have used the IRS2011 in other repairs where the original ic was a IR2011.

[paleeman]

Yup, Diydidi, you're thinking right. When you replace the IR2011 with the IRS2011, a modification is required in the protection circuitry. The protect threshold changes with IRS2011. Remedy - Replace R114 (original value 10R) with a 4k7. But the real PITA is the TC7WH08, (dual in and gate) if you use circuits manufactured by Toshiba, no modifications are needed. In every other case, you will spend hours, calibrating the protect threshold.

[diydidi]

Yup, Diydidi, you're thinking right. When you replace the IR2011 with the IRS2011, a modification is required in the protection circuitry. The protect threshold changes with IRS2011. Remedy - Replace R114 (original value 10R) with a 4k7. But the real PITA is the TC7WH08, (dual in and gate) if you use circuits manufactured by Toshiba, no modifications are needed. In every other case, you will spend hours, calibrating the protect threshold.

Great thanks for that info Paleeman. Will most certainly give that a try.
Are you saying its better to leave the original TC7WH08 than to replace it?

[paleeman]

Well. in most cases he "dies" along with the IR2011. If so, the replacement is a must. Otherwise, leave it. In my experience, if you "mess" with the drive board, after every repair, you have to readjust the threshold. IMHO, Wharf could have anticipated this, and included a trim pot in the protect circuit (like Markbass).

[diydidi]

Well. in most cases he "dies" along with the IR2011. If so, the replacement is a must. Otherwise, leave it. In my experience, if you "mess" with the drive board, after every repair, you have to readjust the threshold. IMHO, Wharf could have anticipated this, and included a trim pot in the protect circuit (like Markbass).

Ok got it. Do you suggest I make R114 a trimmer? How then does one go about adjusting it?

[Jazz P Bass]

Would someone kindly indicate page & coordinates of this 'R114'?

[paleeman]

JPB, you have to look in the Titan 15 Active manual, page 8, near Con 3B or Con 4, connected to the protect pin of the drive board.

In certain versions there is a D28 instead of R114, or it is completely missing from the older versions. Probably, it has been implemented later.

[paleeman]

Ok got it. Do you suggest I make R114 a trimmer? How then does one go about adjusting it?

With a dummy load drive the amp to around 250W, then adjust the sensitivity of the protect circuit to those values, and give 10% or more headroom to it. The voltage on protect pin should be kept below triggering point, 4k7 is usually OK, but if you want it super precise, use a trim pot.

After the first Wharf repair in our shop, when we came across this issue, we spent a lot of hours trying to figure what's wrong. Finally, we came to the conclusion, that, there's nothing wrong with the amp itself, but due to component tolerance and the slight difference between IRS2011 and IR2011, the protect circuit trips far too early.

My suggestion is to try sourcing some IR2011's, it'll save you from this Sisyphean work. (You can order them from Mouser electronics )

[diydidi]

The problem I'm having is with the Titan 12A. I see now it doesn't have this resistor R114, Will I have to add a 4k7 there?

[Jazz P Bass]

I see where the 12A & the Sub 15 have different resistor values on the protect circuit.
The drive boards are identical.

I am having a hard time wrapping my head around how the IRS2011 (compared to the IR2011) has anything to do with the protect circuit kicking in early.

It appears as if the engineers were 'searching' for a solution.

[paleeman]

You're absolutely right. When you consider the facts,everything support what you said. But when you lower the science of the repair on a simple, empirical level, you can experience that replacing the IR with an IRS causes this behavior. And also, you couldn't be more accurate, when you said that the engineers were searching for a solution. Ultimately, the Titan A series amp was discontinued, I presume because of too high failure rate. (Is that a right way to put it? )

[Enzo]

Too many failures? MAybe, but most amp models are discontinued due to insufficient sales.

[tedmich]

the Titan A series amp was discontinued, I presume because of too high failure rate. (Is that a right way to put it? )

That is a perfectly good way to put it! If English is not your first language it might as well be; thank you for sharing your knowledge!