Ok I actually tracked from the junction of C46 & C47 to the next point joined by a jumper track(I think all jumper traces are on top of the board so it is a double sided board) and probably a cold solder point or faulty trace which I bypassed with a short piece of wire. Now I get continuity to pins 7 of all the chip amps, and to the ground points that were "left out" before, through to CONN11.

voltages on the regulators now are:

LM317
Pin 1 adj = 12.4v
Pin 2 out = 13.7v
Pin 3 in = 37.7

LM337
Pin 1 adj = -12.6v
Pin 2 in = -38.1v
Pin 3 out = -13.9v

looking better?

It isn't a double sided circuit so all that is possibly tracable is underneath. What exactly should I look for?

thanks

When you say ground/common you mean real ground or something else? I've tried following the schematic from the mains ground wire to D4,D5,R51 and C39 and across to CONN 11 and up to here everything seems fine. CONN 11 then meets the junction of C46 and C47 and that's fine too. But I get no continuity to the junction of R52 & R53 nor to the junction of C48 & C49 not to the junction of C50 & C51. However there is continuity from the junction of R52 & R53 through to the junction of C50 & C51.

Could this be what's causing all the trouble?

I've tested the 4 resistors and they all seem ok, 215r and 1.8k. I've followed the tracks making sure there aren't any shorts with other tracks or solder points in that area and all is fine. I've soldered back in the LM317 and taken the voltage readings. They are still all over the place and mostly incorrect. I think there may be another problem, that white 2 pin connector underneath the board is not shown in the schematic, well atleast I can't find it anywhere. One of its pins goes to ground and the other goes to the out pin of the LM317 regulator. Here are the new voltages:

LM317
Pin 1 adj = 34.8
Pin 2 out = 36.4
Pin 3 in = 36.4

LM337
Pin 1 adj = 9.4
Pin 2 in = -36.3
Pin 3 out = 8.1

And the power led remains red.

can you point out which ones in the schematic are the resistive dividers?

Ok I pulled out the Lm317, the power led turns green and these are the voltages I'm getting:
LM317
Pin 1 adj = -23.3
Pin 2 out = -22.6
Pin 3 in = 39.1

LM337
Pin 1 adj = -36
Pin 2 in = -38.5
Pin 3 out = -37.1

what now?

Ok I'll try all of this tomorrow, and yes I have pulled all the amp chips out and there's no speaker attached, but I still did hear that very high pitch whistle, it lasted about 5 seconds.

As for the caps, no they're not backwards in terms of polarity, just in terms of component numbering. If you look at the photo of the board showing the two voltage regulators, the far right lug of the LM317 was soldered directly to a hanging track which was shorting with one of the lugs on that small white connector. So this time round I cut off the hanging track and connected the LM317 input lug directly to the +ve side of C46 using a piece of wire. Tomorrow I'll take it out and see if that fixes anything.

http://www.flickr.com/photos/73835524@N00/11085317413/in/set-72157638111984374

What a mess! :duh

well I replaced both of the regulators, triple checking that both are in the right way, and triple checking for continuity to the surround components following the schematic. BTW there is some monkey business in the schematic too C48 and C49 are the other way around and so are C51 and C50, though + and -ve connections are still the same. However powering it on through the limiting lamp I first notices a very high pitch whistle and that the power led doesn't turn green as it had been doing up untill today.
Anyways here are the voltages I'm getting off the regulators:
LM317
Pin 1 adj = 35.4
Pin 2 out = 36
Pin 3 in = 36

LM337
Pin 1 adj = 2.6v
Pin 2 in = -36
Pin 3 out = 1.1

so what went wrong now?  :grr

well I started out today to try and get those voltages written down but something strange was happening, I wasn't getting any voltages anymore, I checked around the whole board and found that the ground wire had snapped off the lug on the mains plug. Fixed that and went ahead to reading voltages to each pin and each chip:

http://www.flickr.com/photos/73835524@N00/11173829406/in/set-72157638111984374

As for the +15/-15v readings there's some strange stuff going on here too, reading off the regulator pins I'm getting:
LM317
Pin 1 adj= -6.5v
Pin 2 out= -5.8v
Pin 3 in= 35.1v

LM337
Pin 1 adj = -32v
Pin 2 in = -36v
Pin 3 out = -34.5v

and here's the other half of the schematic:
http://www.flickr.com/photos/73835524@N00/11174186145/in/set-72157638111984374

Ok I've made the limiting lamp and I've carefully removed all the amp chips. I've done some tests for continuity as you suggested:

Check PINS 1 & 5 = OK ALL CHIPS
Check PINS 3 & 2 = OK U7 ONLY (U8 = Pin 3 to output, Pin 2 to Pin 1) ( U5 = Pin 2 to Pin 1, Pin 3 to ?)
Check PINS 4 & 6 = OK ALL CHIPS
Check PIN 7 = ARE THEY SUPPOSED TO GO DIRECTLY TO GROUND? THEY DON'T
Check PIN 8 = C54 100uf 25v ALL CHIPS
Check PIN 9 = NOT SURE EXACLY WHAT TO CHECK HERE
Check PIN 10= NOT SURE ABOUT THIS ONE EITHER.

And I've also verified that both voltage regulators are in the correct way. What's next?

Also tested the limiting lamp with the amp attached to it, on pins 1 &5 am getting 35vDC and on pins 4&6 am getting -35vDC.

thanks
J.

Well I must say that these bulbs are becoming like good old mullards, not one shop, supermarker, handy store, electronics store etc etc supply them anymore and fridge bulbs are max 25watts. I managed to find a working 40w bulb in an old box in the garage so I'll use that.
I also found an old variac (iskra brand) from the 60's I think, could this be handy too?

I'll start doing all the testing tomorrow, though I have one good question for you, before Roly posted telling me not to turn it on, I had already done so, do you think I'll need new amp chips? or do you think that they'd be fine?

thanks
J.

Yes for some reason I missunderstood Roly's statement - "assuming that you are counting pins from the right end". Anyways I am building up the light bulb limiter, do I need 100 watts? Can it be one of the modern energy saver bulbs or does it have be the good old type? I could find any old type ones at the local handy store!!

thanks

Photo showing pins 1 & 3 unsoldered on U7, there is clearly a track between them:

http://www.flickr.com/photos/73835524@N00/11085319253/in/set-72157638111984374/
I wrote pin 5 on the photo but it's pin 3

Photo showing U8 with pin 1 floating:
http://www.flickr.com/photos/73835524@N00/11085206006/in/set-72157638111984374

Photo showing U9 + U10 + U5:
http://www.flickr.com/photos/73835524@N00/11085317413/in/set-72157638111984374

U9 + U10 have their heat plates not facing the main heatsink which is on the top of all 3 photos.

thanks
J.

Just signed up and downloaded the whole schematic, payed 9$ for it, but that's fair enough instead of going on in the dark!!

Here are some photos of what's under the board:
http://www.flickr.com/photos/73835524@N00/sets/72157638111984374/

Looking at the top of the chip(where I can see LM3886T written) and counting the pins from right to left (if this is the correct way to do it)  pins 1 and 3 are tied together on U7. Actually this looked quite normal to me as there is a path going from one pin to the other. Looking at the schematic and judging from what you logically say, pins 1 and 3 should not be tied together!! Factory monkey business?

thanks
J.

I have been insisting on this since this active speaker was brought to me, but the distributors and techs of this brand are not willing at all to let the schematic out of their bonds for some unknown top secret reason. This brand is DB and the model is OPERA LYRIC 215. It has been discontinued so I really don't understand why they aren't willing to let the schematic go.