Re: Tannoy Reveal 6D

Success, I guess?

The speaker is once again sounding good and could potentially be put back into service. I made some updates to my webpage with some other foibles along the way.

A few numbers: the audio input board pulls ~58mA on both the + and - lines.

The 220 ohm resistor before the LM7915 has about a 14V drop -- 39.5V to 25.5V and dissipates almost 1W. I'm using a 5W axial resistor for this and it's getting too hot for my liking.

The 120 ohm resistor before the LM7815 has about a 7.3V drop -- 39.5V to...

Re: Tannoy Reveal 6D

The lack of instant gratification was a little let-down but I'm looking forward to finding the actual fault now.

I think the toner transfer method would work better for me if I started with better tools. My first pass with high-clay content magazine paper (has worked for me in the past) was a complete dud, no toner stuck to the board. Clean up, try again. Attempt number two with PSA label paper, labels removed, worked OK but under 10x magnification I noticed thin lines of missing toner where the original labels were die cut. Out came the sharpie....

Re: Tannoy Reveal 6D

A few things finally left the bench and I had some time to work on this. I've documented it a bit more on my webpage:

[url]http://www.cs.wisc.edu/~timc/e/tannoy.html[/url]

To summarize, L1, the 120ohm 5W resistor smoked my amp board a few years ago so I etched another one last week. I populated the board, tested the voltages, installed it. No good -- L1 gets stinking hot, 190F/88C, quickly.

Next things on my list are to disconnect the digital board -- we'll see if it's there. If not, it's the input board I suppose. In...

Re: Tannoy Reveal 6D

Hah, yes, I did that for a while and it worked. But something on the board failed again and I ended up elbow-deep in the project. I might be slow but I do occasionally surprise myself and finish projects!

Re: Tannoy Reveal 6D

Yes, it should be possible to differentiate traces via intensity levels, but the board is almost entirely the same shade of green. Levels that work in one part of the board completely botch the rest. My wonderful wife -- who deals with Photoshop and InDesign professionally -- spent way too much time trying to find a way to make it work.

Here's what I have, scorching and all:
[url]https://www.dropbox.com/s/4dp6atwzarfujhv/tannoy_amp_1.png[/url]
[url]https://www.dropbox.com/s/tc0axbl9d1cuw1e/tannoy_amp_2.png[/url]

So I think...

Re: Tannoy Reveal 6D

I know I'm replying to a relatively old thread but this has been a project on my list for a while. I found pretty much no information on this a few years back -- sat down to revisit the issue this weekend and this thread was a great find.

I have a set of the Reveal 6D. A couple years back, L1, the 120R 5W resistor failed and did a pretty good job of charring 7600 1556 amplifier PC board.

I unsoldered all of the components on the damaged board, cleaned up the brown glue and made a couple of high-resolution scans of the bare board. My...