Wharfedale Titan 12 Active

[Bigbaz]

Hi, I have some problems with a Titan 12A & hope someone can help? (I have a 15A circuit - looks very similar)

Fixed a dry joint on R528 3K9 - was causing noise, blew up the driver pcb with an earthed soldering iron while caps still charged! - Doh! Replaced driver board. All looked good until while using it one day I had to power it off to move it (while it was warm) & it wouldn't turn back on.

On test if I run it till it's warm (hair dryer too may be :-) & power off for 15 seconds, power back on there was a loud thump in the woofer & no smps. Would not run till it cooled down. Found several things.... found R33 2R2 0V to chassis open circuit (not burnt, just open, like a fuse that had blown) I wondered how that could be as there was no obvious circuit that could cause massive current to flow in the 2R2, but I also noticed that C23 1000uf on the +70V line discharged to slightly LESS than zero volts! All during that power on thump! I re-drew the circuit to see how the circuit was being "completed" & began to wonder about how good the insulators were on the mosfet & diode tabs? By this time the heat sink threads were worn out & it did not fit together well, so I have glued some nuts on to the inside of the heat sink, replaced all the mica insulators AND done a 500Vdc insulation test from the tabs to chassis ground. Looked good so back to testing..... No more thump in the woofer, 2R2 stays OK, but the smps still fails to power up when all is warm. If I leave it powered on for say 10hrs, no signal so little amp heating, but the psu & heat-sink are warm, then it'll power cycle no problems. If I run a signal through it for a while, it won't power back up after a 15 second power down (no thump, 2R2 still intact, so insulators now looking good at least :-)

So..... looks like it's a temperature problem in the LF amp? (ok with just the psu warm etc) I have removed the 2 x IRFP4229 & notice that the "ON" resistance gets lower if I heat them up, so could be a bit of a surge once it's warm? I have ordered 2 new IRFP4229 to see if that helps.

I'm also wondering about a power on mute? It looks to me like there is NOT such a thing (please tell me if you know where it is?) so I'm thinking that power cycling it while there is still some charge left in the psu AND no power on mute along with the lower on resistance in the mosfets could be my problem? i.e. big surge through the output mosFets.

So... how about putting a cap, say 25uF across Q8 on the driver pcb as this is the amp PROTECT line - this would keep the drive to the output mosFets OFF for a short time & give everything a chance to stabilize before turning on the drive......

Any thoughts much appreciated :-)

Thanks in advance...

[diydidi]

i would suggest "divide and conquer".
Does the driver board (if were talking about the same board), I presume SMPS driver board, have any smd caps on it? Regardless check them for hi ESR.
Rds on for Mosfets actually increase with temperature for a given Vgs, See attached graph.
Anyways, Also check the startup and over voltage resistors. I have found that in some units they differ from the schematic. Hell knows why.
Good luck.

[CunningArtificer]

I know this is a long dead thread but...

My titan 12 limit light is fixed on. Preliminary checks show the class D board has a burned out r7, is there a usual underlying cause for this? Just want to check how deep I'm going to have to go.

Any help appreciated.

[Jazz P Bass]

What is an 'r7'?

Can you post the relevant schematic?

[CunningArtificer]

What is an 'r7'?

Can you post the relevant schematic?

The schematic is further up the thread. R7 is a resistor, hard to make out the values as it is a little frazzled.

[mozwell]

R7 on the titan 12D sch is 2M 1/4 W
R7 on the titan 12 sch is 100k 2W

[fotanka]

Hi, I have in my company too. Some body tried to repair and gave damage to some tracks. But they cann't. Problem in class D amp. When I checked signal from pin 1 (LF-Input) it is ok. Then I checked U6 out put pin, I can see PWM is ok. I checked U8 7-3 pins signal ok. But when Q8 installed there is no signal on U8 pin 7-3. I checked all output components there was no problem. During testing I didn't install output fets. On output fets I see pwm is ok. But I cannot see any audio signal on out put. Interesting I only see a little square wave and changing with input signal. I need to solve problem. Now I am using IRS2011S and many time ı changed IC but every time i saw the same signal on output. How can I solve the problem.

[Jazz P Bass]

In a Class D output, the signal IS a square wave.(well, a rectangle of sorts)



The filtering element stage after the output IC's is there to remove all but a few 10's of millivolts of it.

[fotanka]

I konw a little how class D working. When I am working on equipment usually I am using a serial bulb on mains. For this class D amplifier I am using IRS2011S. I dont know maybe it is problem. I measured rail voltages they are +-53V. But i always saw -43 or like this on output. I uninstall fets i saw too. Now I belive that I have problem with IRS2011S. Maybe not correct for this amplifier. I said before, I sending 100Hz from audio generator ı saw pwm on drive pıns also on gates. I am ınstalling fets but there is no output signal. I only see a little like square wavw and it is changing with input signal level.

[snipedoguk]

Overheating Titan 12

Hello.
I can post the schematics, but I can do better than that. State your problem and I'll help you solve it. I have quite an experience with these units.

Hello paleeman, I wonder if you could point me in the right fault finding direction with an overheating Titan 12. The unit runs very hot, and after 10 to 15 minutes at moderate volume the bass driver amp will eventually shut down. When left to cool and turned off and on again it resets OK, and will run OK again for 10 to 15 minutes. In all other aspects it seems fine. I have your copy of the schematics for the Titan 12, and i have the other speaker of the pair, which works fine, and doesn't run anywhere near as hot. This is the older Titan 12, not the "D" version, though I understand this is also a Class D amp?

Thanks for any pointers you can offer.
S

[diydidi]

This is why the "A" s have been discontinued. Replace the Class D driver board. You can also try fixing it as Paleeman suggested.

[snipedoguk]

Hello diydidi,
thanks for the rapid reply.
As you say, since it is discontinued Wharfedale no longer supply parts for the A series, do you know of a source for the Class D board?
Which of Paleeman's fixes would be relevant to an overheating problem?

Thanks
S

[Bigbaz]

Update...

Hi, I have some problems with a Titan 12A & hope someone can help? (I have a 15A circuit - looks very similar)

Fixed a dry joint on R528 3K9 - was causing noise, blew up the driver pcb with an earthed soldering iron while caps still charged! - Doh! Replaced driver board. All looked good until while using it one day I had to power it off to move it (while it was warm) & it wouldn't turn back on.

On test if I run it till it's warm (hair dryer too may be :-) & power off for 15 seconds, power back on there was a loud thump in the woofer & no smps. Would not run till it cooled down. Found several things.... found R33 2R2 0V to chassis open circuit (not burnt, just open, like a fuse that had blown) I wondered how that could be as there was no obvious circuit that could cause massive current to flow in the 2R2, but I also noticed that C23 1000uf on the +70V line discharged to slightly LESS than zero volts! All during that power on thump! I re-drew the circuit to see how the circuit was being "completed" & began to wonder about how good the insulators were on the mosfet & diode tabs? By this time the heat sink threads were worn out & it did not fit together well, so I have glued some nuts on to the inside of the heat sink, replaced all the mica insulators AND done a 500Vdc insulation test from the tabs to chassis ground. Looked good so back to testing..... No more thump in the woofer, 2R2 stays OK, but the smps still fails to power up when all is warm. If I leave it powered on for say 10hrs, no signal so little amp heating, but the psu & heat-sink are warm, then it'll power cycle no problems. If I run a signal through it for a while, it won't power back up after a 15 second power down (no thump, 2R2 still intact, so insulators now looking good at least :-)

So..... looks like it's a temperature problem in the LF amp? (ok with just the psu warm etc) I have removed the 2 x IRFP4229 & notice that the "ON" resistance gets lower if I heat them up, so could be a bit of a surge once it's warm? I have ordered 2 new IRFP4229 to see if that helps.

I'm also wondering about a power on mute? It looks to me like there is NOT such a thing (please tell me if you know where it is?) so I'm thinking that power cycling it while there is still some charge left in the psu AND no power on mute along with the lower on resistance in the mosfets could be my problem? i.e. big surge through the output mosFets.

So... how about putting a cap, say 25uF across Q8 on the driver pcb as this is the amp PROTECT line - this would keep the drive to the output mosFets OFF for a short time & give everything a chance to stabilize before turning on the drive......

Any thoughts much appreciated :-)

Thanks in advance...

UPDATE
So...... at one point I thought I had solved the problem, so I bought a second unit so I had a pair to use or sell as a pair...... I discovered the second speaker was exactly the same! It would run all day without problems, but power off while it was warm, wait 10-15 secs & no power up. Just a loud thump in the speaker, no green LED, PSU no starting up. (NB - a 2R2 resistor to chassis ground would sometimes go open circuit - no burning just open, like a fuse)

I contacted Wharfedale in the UK & was told that the "12A was not one of their best products" their "solution" was to offer me TWO new amplifier modules at a cost that made it uneconomic.

I sold the two 12A's as faulty & moved on :-)

Lesson learned!