Tannoy Reveal 6D

[andymees]

Thanks midibob! Perfect.

[midibob]

Try here...
https://elektrotanya.com/tannoy_reve.../download.html

[andymees]

Hi All
Bit late to the party, but I've got a pair of Precision 6Ds here and one of them just died on me. I'm not an electronics whiz sadly, so it's unlikely theres anything I can do to fix it, but I was hoping I might be able to get hold of the schematics so that I can provide them to a suitable tech, if I can find one. Tried the links in post #28 put obviously its been a while and the links seem to be dead now. Is anyone able to help out with a new link?

If it's of interest, the issue with the (right) monitor is that sound output has cut out... it powers up ok, but theres no sound... except when I power off, when, just for a brief moment as I cut the power the speaker will burst into life and the missing sound outputs, as normal, just for a second.

Huge thanks in advance if anyone can help with those schematics
Cheers
Andy

[Valden]

I've just completed my latest repair of a Tannoy Reveal 6D monitor. It was making a crackling noise on start-up, which would last for ten or twenty minutes, if not more. The audio output would be cracking too. But it would go away and the sound would eventually be fine. I suspected capacitors. (Edit - my kids told me it was making a very annoying high pitched sound as well, but I couldn't hear that. I'll ask them if it's gone.)

Upon disassembly and diagnosis with an audio probe and separate amplifier I found that the crackling sound was not present at the output of the filter board or at the input to the amplifier ICs on the power board but was present at output pin 10 of both amplifier ICs. So, it was likely to be a problem with the power supply on the board, rather than one of the amplifier ICs. Probing with a multimeter showed that many of the electrolytic capacitors were even weirder than they usually are when assessed while mounted. I removed all of the electrolytic caps (except the two, big, 10,000 uF ones). About 70% of these were dead or way off. Two of the resistors (no 19 and 21) were also out of spec. I replaced all of the small electrolytic caps and the two resistors at a cost of about $5. This Tannoy Reveal 6D monitor is working again. Yay.

But the main reason for writing this note is to describe the disassembly and reassembly process, which is tricky, given how there are hidden screws underneath the heat-sink and the transformer. Dealing with these could be fun - or not. Let me describe what you will find and how you might proceed.

There is an aluminium plate onto which all of the monitor's main elements are mounted. This is held into the wooden speaker box with six, 3mm hex cap screws.

The power board is mounted onto the plate with five screws with flat, countersunk Phillips No 2 screws, which are hidden underneath the heat-sink.

The large heat-sink is screwed onto the plate with eight screws from the inside. Seven of these are round headed Phillips No 2 screws. Some are hard to get at due to the power board. One of the eight screws is a flat, countersunk screw with a Phillips No 2 head. This one is hidden underneath the transformer. (Note that it has the same thread and head as the screws for the transformer, but is shorter than those four screws.)

The transformer is mounted onto the plate with four flat, countersunk screws which have Phillips No 2 heads. These act as bolts, onto which 7mm nuts are fitted from the inside. The top two of these bolt/screws are hidden underneath the heat-sink. As such, if the heat-sink is still in place, they can't be held with a screwdriver while the nuts are loosened. It becomes a chicken and egg situation as you try to remove either the heat-sink or the transformer, so that you can remove the power board.

First, undo the seven round headed screws which hold the heat-sink onto the plate from the inside. The last, hidden screw will still hold the heat-sink onto the plate, but it will pivot. Be careful that its pivoting action does not damage switches on the filter board. To pivot the heat-sink so that the screws for the transformer are Revealed (the real reason for the monitor's name!) remove the power cable socket and the power switch. Pivot the heat sink, smearing white heat paste everywhere, then hold the transformer's screw heads with a screwdriver so the corresponding nuts can be loosened. Or, another way could be to use a cold-chisel and hammer to shear through one or both of the top two screws that are holding the transformer on. Or use a hacksaw blade to cut one or both of them. This is what I did. First a hacksaw blade cut through half of right-hand screw, then a chisel cut the remainder. With only one partly loosened screw holding the transformer on, it could be pivoted to Reveal the last screw that was holding the heat-sink on. Ta da! The heat-sink was removed, then the power board. I left the transformer loosely connected to the plate and put it aside.

For reassembly, the best thing to do is to use strong epoxy to fix the transformer mounting screws into the plate, so they will remain still while their nuts are being tightened later. With these screws glued into place, the power board can be installed (using thermal paste for the ICs and thermal fuse), then the heat-sink can be installed (using thermal paste) and lastly the transformer. But do a brief performance check before full reassembly. Brief, to avoid cooking the amplifier ICs, which will be lightly screwed onto the aluminium plate for this test, but without the large heat-sink in place.

Or course, if you want to be able to reuse the transformer mounting screws, destructive removal is not advised.

But most of all - feel encouraged to dive in and fix your Tannoy Reveal 6D or 8D monitors. Chances are, if you're reading this you've already become adept at repairing them. :-)

[midibob]

Re: Tannoy Reveal 6D

Well, after starting this thread all those years ago my other 6D failed the other day with the speaker cone almost jumping out the box and a loud hum.

On strip down I found the -15v supply resistor had failed (220R 5W). When replaced I noticed it was running far to warm for my liking. This was due to the digital board which I don't use so it was disconnected as I couldn't be bothered to fault it.

All now fine.

[micdim]

Re: Tannoy Reveal 6D

It isn't anything special, nor does it need to conduct any meaningful amount of current. Your biggest concern is to find something that's mechanically compatible, so... You or your tech will just need to remove the little front plate and start digging through parametric searches on parts distributor websites, I'm afraid.

Yes I will will convey this to my New Tech. My previous Tech doesn't seem to want to do the research work.

Thank you!

[Khron]

Re: Tannoy Reveal 6D

It isn't anything special, nor does it need to conduct any meaningful amount of current. Your biggest concern is to find something that's mechanically compatible, so... You or your tech will just need to remove the little front plate and start digging through parametric searches on parts distributor websites, I'm afraid.

[micdim]

Re: Tannoy Reveal 6D

"Bypass switch", as in, the mute switch? Or...?

Yes the mute switch. Thanks!

[Khron]

Re: Tannoy Reveal 6D

"Bypass switch", as in, the mute switch? Or...?

[micdim]

Re: Tannoy Reveal 6D

Does anyone have the actual schematic for the Tannoy Reveal 8D Bypass Switch. I'm told it's not on the schematics that were here. I downloaded those, but my tech says it doesn't show the Bypass switch specs?

I would very much appreciate it, and Thank you!

[240vchris]

Re: Tannoy Reveal 6D

In my case the digital board was causing some sort of short which caused no sound but my LED would go dim also.

I solved my issue by simply disconnecting the digital board as i never use the digital input anyway, and they're still fine to this day.

I would recommend starting by disconnecting that digital board first, put everything back together and turn them on again to see if it remedies the issue.
My original posts are on page 3 and 4 (with the default post amount setting per page.)

seems you could be right!
digital i.o disconnected after snapping a few cables on the connectors and replacing them i fired it up for quick hillbilly bench test. (see pics )

they popped and hissed a little. turned them off quick as they do get very warm turned them on a second time with a little wiggly waggle here and there i believe i also have another defect cable connector.
gotta find a replacement cable now or hardwire it?

might also place a new heatsink on the back and weld the 2 wire wound resistors on.
one step at a time
thx man

[waveform]

Re: Tannoy Reveal 6D

ok here goes i got a pair of 66d's and one of them decided to give up. before searching online i took the whole thing apart and now i dont know how to put it back together

absolutely disgusted with the amount crap smeared around the pcbs. appears that all here are in agreement there?
powers up fine the led on the front switch works, on the signal input i got nothing the red green led o the backside any hints tips would be appreciated
schematics here ive downloaded, could but not wanting to crack the working one open (i will cry when i see more crap glue) and swap boards to narrow it down. but i am willing to upcycle the few bits that get metioned here more than once i.e the ceramic 5w resistors and some caps.
much love for this forum 240vchris

In my case the digital board was causing some sort of short which caused no sound but my LED would go dim also.

I solved my issue by simply disconnecting the digital board as i never use the digital input anyway, and they're still fine to this day.

I would recommend starting by disconnecting that digital board first, put everything back together and turn them on again to see if it remedies the issue.
My original posts are on page 3 and 4 (with the default post amount setting per page.)

[240vchris]

Re: Tannoy Reveal 6D

ok here goes i got a pair of 66d's and one of them decided to give up. before searching online i took the whole thing apart and now i dont know how to put it back together

absolutely disgusted with the amount crap smeared around the pcbs. appears that all here are in agreement there?
powers up fine the led on the front switch works, on the signal input i got nothing the red green led o the backside any hints tips would be appreciated
schematics here ive downloaded, could but not wanting to crack the working one open (i will cry when i see more crap glue) and swap boards to narrow it down. but i am willing to upcycle the few bits that get metioned here more than once i.e the ceramic 5w resistors and some caps.
much love for this forum 240vchris

[Khron]

Re: Tannoy Reveal 6D

The crossover section is, i would guess, pretty much identical to the 6D. The main difference is in the amplifier section, where the woofer gets a bridged pair of LM3886's.

How about you maybe try to describe the problem(s) you're facing, perhaps?

[bahudoord]

Re: Tannoy Reveal 6D

Hello
does anyone have the schematics for the Tannoy 8D

thanx
deep

[Khron]

Re: Tannoy Reveal 6D

The connectors to the speakers are wonky as hell too - on my left-side one, the spring-tongue broke off from inside the output line female side not long after initially fixing the electronics the first time around, so i ended up soldering that wire to the bottom of the board.

And earlier this year, the black gunk corroded the 7.5k resistor in the mute circuitry, which knocked out the auto-mute on power-up / power-down.

[Valden]

Re: Tannoy Reveal 6D

Hi Khron. The speakers on my Tannoy Reveal 8Ds have both lost their ‘spish-spish' highs too. Haven't managed to get them fixed yet. Hopefully it's the trim pots, which I have already had a fiddle with. I might just replace them.

My 6Ds are working pretty well at the moment. When the 8Ds crapped out a few weeks back I got serious about fixing the problem with the 6Ds reported in my last post. In that I thought the thermal fuse was playing up, but in the end I got the problem monitor working again by simply stripping it right down and cleaning all the sticky, gooey, crusty gunk off. Lo and behold, upon reassembling, it worked. As reported by others, it seems the gunk causes problems and should be removed as a first step. Hard to do, but having a variety of pick tools to hand helps.

Keeping these monitors working is worth it and not that hard to achieve. I have the schematics if anyone needs them. 🙂

[Khron]

Re: Tannoy Reveal 6D

Slight update from this side as well.

It must've been a couple months ago that the tweeter output in my right-side Precision 6D died out. But since i hadn't done any mixing or critical listening, just watching YouTube and some series, it didn't bother me all that much. Not enough to take it off its place (bit uncomfortable to reach), crack it open and see what's what.

That is, until last night, when the left-side one went totally mute. Voltages looked ok, S/PDIF was locking on (LED on the back went from red to green), DAC-to-crossover-board cable was ok, power amps & drivers were ok (jiggling the switches made a bit of noise). So i "chiseled off" the black gunk off the ends of the cables, double-checked the speaker connectors, and it finally came good.

Mostly the same routine with the former (right-side) one as well, except without improvement. That is, until i decided to give the tweeter level trimpot a twist. And lo and behold, with some initial crackles, the tweeter came back!..

<sigh> I really gotta see when and how i can scrape together some cash, to finish my project to overhaul the electronics in these.
Got the two TAS5630 class-D amp boards almost fully populated, just gotta wind the output inductors (got the cores, need appropriate wire).
Got the little DSP boards pretty much designed (ADAU1701, tap off the I2S signals from the DAC board), still need to get the PCB's manufactured, plus the little adapter board for the DIY "USBi", and some panel-mount miniUSB's.

[Valden]

Re: Tannoy Reveal 6D

This is a fresh post to this very helpful thread, seeking assistance with identifying the thermoswitch on the power board of my Tannoy Reveal 6D monitor.

Diagnosis: The music was fading out in one monitor, which was the master of the S/PDIF pair. The other monitor kept playing, so I suspected a problem with the audio or power circuit in the problem monitor. Upon inspection, I found that the trace between the transformer connector's pin 3 and the thermoswitch was broken. Soldering in a jumper wire to replace the trace got the monitor working again - for about four minutes from a cold start, at which point the music fades with crackling over a period of about 10 seconds, to nothing. This replicated the fault I noticed before disassembly. If I jump the thermoswitch with a test lead, between that transformer connector pin 3 and the near side of diode 3, bingo, I've got music again (see pic below). That switch is looking guilty. :-|

Any info on what it's specs are, or might be? Sourcing a form/fit replacement could be tricky/expensive/slow, so I might use a switch with suitable specs, should one be available at the local Jaycar store. I'll mount it near the amplifier ICs, so it can feel the heat. Another option would be to just bypass the thermoswitch permanently, though I worry about the missing protection for the amps. From studying the power board schematic I gather that the thermoswitch works by muting the amps when it opens due to excessive heat. Upon opening, current flowing through the amp's pin 8 drops below 0.5mA, muting it, which stops it from operating and getting hotter. A point to note is that the amps (Texas Instruments LM3886) include built in thermal protection. They shut down at 165℃ and start again at 155℃. Not ideal, but an OK temporary fix. The heat sinks for the amps are quite substantial, after all. :-)

[Khron]

Re: Tannoy Reveal 6D

Tiny update.

The other day, the tweeter in one of my Precision 6D's seemed to go out of commission.

Removed the back plate, cleaned off the speaker output connectors on the power board, removed the contacts from the tweeter connector housing, bent the "tongues" inside the contacts so they press harder onto the pins on the board.

Whaddya know - tweeter came back to life

Propped the speaker back to its rightful place, and guess what - woofer sound went away...

After some messing around, i figured i'd start flipping switches, and it turned out the 80Hz high-pass switch was the guilty party. A squirt of contact-cleaner and 20-30 operations later, all was well (and stayed that way)

Now, for a more long-term plan:
1) redesign the filter board - reusing the connectors, surface-mount resistors, film caps and DIP-switches; NOT reusing any of the ceramic, electrolytic caps or opamps (replacing them with either NJM2068's or NJM5532's);
2) redesign the power supply & amp board - "piggyback" / retrofit a stereo class-D amp (2xBTL) board; reuse the big fat electrolytics; change the power supply to be a full-wave rectified +39v only, for the power amp; add a 1A bridge rectifier & a pair of cap-multipliers to work as discrete regulators (bolted to the existing heatsink) to power the filter board