Tannoy Reveal 6D

[midibob]

Hi,

Just picked up a pair of these, one good and one faulty.
Now, you would think Tannoy is renowned for quality but you can make your own mind up after reading this!

These are made in China (isn't everything these days, no wonder we're all in debt) and you can probably see from the pics that they have a surplus of this horrible glue stuff. On the plugs and sockets it's just a nuisance but if it's used near anything that generates heat then it goes conductive after a while as can be seen. I'm debating whether to remove all of it which will probably mean replacing all the caps.
That brings me to the next thing. I was expecting a Tannoy product to be using pretty decent caps Rubycons perhaps, nope! Panasonics then, nope! Nichicons, nope!


Well hows about Su'scon!!!! Oh dear. It looks like they'll all have to come out anyway.

The fault on this one appears to be well known in that the speaker cone sucks in on power up with just a hiss coming from the tweeter and no output. As I've only just got it apart I don't know what the problem is yet but until I get all that gunk removed and the caps replaced further diagnostics are pointless. Luckily both speaker and tweeter appear to be OK which is a relief.
When I've sorted this one I'll do the good one as I suspect it won't be too long before it packs up.
Watch this space!!

Bob

[Th3_uN1Qu3]

Re: Tannoy Reveal 6D

The fault on this one appears to be well known in that the speaker cone sucks in on power up with just a hiss coming from the tweeter and no output.

Blown amplifier, output sticking to one of the DC rails. Disconnect the speaker or you'll burn it (if it hasn't been damaged already...). Shame on them for not including DC fault protection tho.

Su'scon isn't that bad for general purpose caps. If the amplifier is regular class B then those caps can stay.

[midibob]

Re: Tannoy Reveal 6D

Well, it looks like all the caps might be OK. Certainly out of cct testing shows that to be the case although the main supply filter caps will be investigated under working conditions later.

So far R18 on the amp board has gone open cct as has L1 ( 120 Ohm 5W ceramic resistor?). This feeds the 15v regulator so there could be a problem on one of the other boards as the reg tests OK.
I've managed to get most of the hardened gunk off but where it's been squirted all over the connectors and wires it almost impossible to get rid of it.

Anyone know any chemicals that will just attack the gunk and not anything else? Tried various alcohols and carbon tet but it doesn't shift it, hard or in it's elastic state.

Looking in the spares drawers and I don't have a 120 Ohm 5W, damm! Ebay here we come.

Bob

[Th3_uN1Qu3]

Re: Tannoy Reveal 6D

Losing a rail in the preamp will get DC on the output too... so there is a possibility that the main amplifier is alright and you only need to replace that resistor.

[midibob]

Re: Tannoy Reveal 6D

The -15v reg (7915) had gone through cct which is unusual as they normally short, protecting the rest of the circuitry.
Once replaced I noted something else was dragging down the - 15v rail.
Traced this to 1xLM837 ans 1xLM833 on the preamp crossover board. Don't have any of these in stock either (groan)!
Once removed and also with the digital input board disconnected both rails were now OK.
When the digital board was reconnected both the rails dropped to around 6v. A few SMD devices on this board so not looking too good although I won't be using a digital connection so all is not lost. Removed a load of gunk from this board too!!

The only device on this board that uses the -15v is another LM833 (SMD this time) but it appears OK or at least all the i/p o/p's are sitting at 0v. Might have to remove it anyway just to be sure.

Happy days!
Bob

[midibob]

Re: Tannoy Reveal 6D

All now fixed. It was only the resistor and regulator after all!
I had put a variac in the mains lead whilst testing and of course it dropped the main voltage enough to drop the input to the regulators, doh!

No IC's needed, hurrah, and no bad caps either for a change.
I'm sure I'm getting too old for all this stuff.

Midibob

[toastygoodness]

Re: Tannoy Reveal 6D

oh this is sad... tannoys are still sold at a premium, but last i demoed all studio monitors have pretty much converged to the same-ish quality, just different tunings (if that makes sense)... oh well. at least your problem's fixed!

[midibob]

Re: Tannoy Reveal 6D

Spoke a bit too soon. Output went distorted and then disappeared completely.
Found R18 had burnt. I originally thought it was a 1K5 but realised it couldn't be as it was getting really hot.

Next step was to phone Tannoy and ask what the value was. The nice man in the service department said he'd mail me the schematic, which he duly did.
Now that's what I call service.

Other manufacturers take note!

It turns out it should be 7K5 and once replaced the sweet sounds of the speaker returned.

Midibob

[Radio Fox]

Re: Tannoy Reveal 6D

...So far R18 on the amp board has gone open cct as has L1 ( 120 Ohm 5W ceramic resistor?)...

Sometimes inductors are packaged & colour coded similar to resistors. That component could well be a 120uH inductor (otherwise it would have an "R" designation).

I know that you now have it running OK, but now that you have the schematic, does it show L1 as 120uH?

[midibob]

Re: Tannoy Reveal 6D

Hi Radio Fox,

Most definitely resistors. The types you're talking about are the same size as .25 or .5W resistors. These are ceramic blocks as can be seen from the pictures.
The board is strangely marked L1 which is why I put a question mark by it.
The schematic does have them listed as R however.

There was never any doubt in my mind that they were resistors as they feed the 15v power regulators.

Midibob

[Radio Fox]

Re: Tannoy Reveal 6D

Hi Radio Fox,

Most definitely resistors. The types you're talking about are the same size as .25 or .5W resistors. These are ceramic blocks as can be seen from the pictures.
The board is strangely marked L1 which is why I put a question mark by it.
The schematic does have them listed as R however.

There was never any doubt in my mind that they were resistors as they feed the 15v power regulators.

Midibob

Ahh...sorry. I didn't realise that those 2 power resistors were L1 & L2. I only looked at the photo of the top side of the board, & L1 was hidden behind the heatsink.

I take it that L2 is also a resistor (220 Ohms)?

[midibob]

Re: Tannoy Reveal 6D

Sure is.
All very odd!

Midibob

[Djoe The Architect]

Re: Tannoy Reveal 6D

Hi there guys, I seem to have a similar problem and was thinking of giving it a shot at fixing it; But I've already come up against a pretty basic problem : I can't get the amp out! Could you maybe give me a few pointers, I took out the main 6 screws on the back but there is no sign whatsoever of movement, the back plate is well and truly stuck in there...
Thanks for any help you can give me..!
Regards,

Joe

[midibob]

Re: Tannoy Reveal 6D

Hi Joe,

I hit this one too.
The best way I found to release it was to use a rubber mallet and keep lightly taping the fins of the heat sink till it releases.
My definition of taping is light taps, not knock six bells out of it otherwise you could damage the heatsink.
You should find it will come out without too much effort.

Good luck
Midibob

[GoochC]

Re: Tannoy Reveal 6D

Midibob

Do you have the schematic. If so can you email it to me?

[midibob]

Re: Tannoy Reveal 6D

Sure, PM me your mail address and I'll send it over.

[islou]

Re: Tannoy Reveal 6D

Hey Midibob,

Also have myself a set of revel 6D's which i'm having some problems with. Sounds very much like a dry solder joint on mine though, i completely lose sound and have to tap the controls on the back of the speaker to get it back. Strangely its starting to happen to the second of the pair too.

Was also a little disappointed on quality when dismantling them. Either way, went over what i thought were all the relevant solder connections but dont seem to have had much luck.

Don't suppose i could also grab the schematic off you ?

They do sound great when they are working !

[midibob]

Re: Tannoy Reveal 6D

Hi Islou,

You can get problems with the micro switches which can be a pain as they appear to be sealed, at least enough to stop cleaning fluid getting in. I seem to recall the the single switch next to the 8 switch block is the worst so I usually just give it a few clicks and it goes away for a while.

One thing definitely worth doing is removing the gunk around the two power resistors as this goes conductive and eats into the track! You can use a dab of silicon sealant to keep them in place. (don't use a glue gun!)

PM me your mail address and I'll send it over.

Midibob

PS:
If anyone knows a source in the UK for 120 ohm 5W radial cement resistors I'm all ears. Nothing on Ebay unfortunately.

[Foggy]

Re: Tannoy Reveal 6D

Sure, PM me your mail address and I'll send it over.

hello,

I've inherited a couple of broken 6's of various ages, all with seemingly different issues across them all. After contacting Tannoy direct they are saying that they no longer hand out schematics.
Could you send me a copy of the schematics you have?

cheers

Foggy

[midibob]

Re: Tannoy Reveal 6D

Hi Foggy,

I've sent you a PM.

Cheers
Midibob