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Brooke Amplifier Problem

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Category: General
Forum Name: Amp Forum
Forum Description: The 'Stopping Jake Fielder moaning constantly' forum description...
URL: https://forum.speakerplans.com/forum_posts.asp?TID=81051
Printed Date: 19 March 2024 at 9:44am
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Topic: Brooke Amplifier Problem
Posted By: JayeJSAV
Subject: Brooke Amplifier Problem
Date Posted: 08 August 2013 at 5:06pm
Hi there,

I have a Brooke E172700 Amplifier in for service, and could really do with a service manual. I've tried Impact, however they don't have any.

Does anyone have one lying about somewhere / stashed in an archive?

Cheers

Jaye



Replies:
Posted By: Tan-2
Date Posted: 08 August 2013 at 7:49pm
what is the fault, or is it just a clean service?

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 08 August 2013 at 8:02pm
Stuck in protect.

Given it a full clean so far and replaced couple of scratchy pots on front. If I remove chB from relay board it resets however it's not keen otherwise. No DC found on output (metered Pre-relay) and I can't find my amp transistor tester. It's right handy :(


Posted By: Tan-2
Date Posted: 08 August 2013 at 8:12pm
upload pic of amp so we can get better idea....also if there is a working channel use this to carry out check and compare non working channel.

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 08 August 2013 at 9:11pm
It's currently in pieces, as I'm testing the transistors, however it is labelled as an "S 4.2 AMP Technology from USA - 20070727", using MJ15024G Output Transistors.

Here's a pic of the board.....

https://docs.google.com/file/d/0B7kobMSfkbt8MEI3dFJZd1FrcmM/edit?usp=sharing


Posted By: Tan-2
Date Posted: 08 August 2013 at 9:24pm
link is not working....if the amp powered up before being taken apart no fuses have blown then is may have gone dc.. check the small driver transistors followed by the vas circuit..

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: Tan-2
Date Posted: 08 August 2013 at 9:31pm
The protection circuit will hold off the relay if dc offset is say 1 volt of more, test point at the amp o/p before the relay latch this would be between the low value .33 ohm white large resistors these feed back to the emitter legs of the t-03 o/ps.

see how you get on.


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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 08 August 2013 at 10:08pm
Yep, full power up, fan, relays switch out, red protects leds, then it stops there. just sits in that condition till kingdom come. Still hunting down my test kit! It's here somewhere.... :(




Posted By: JayeJSAV
Date Posted: 08 August 2013 at 10:58pm
So, now I have found my tester (mini applause!!!), I have got 7 out of 12 shoting T-03's, and heading into the drive section. Nice!!

Thanks though x


Posted By: Tan-2
Date Posted: 08 August 2013 at 11:04pm
Did the amp just go in to protection? also when fitting new o/ps the amp stage will need biasing and scope/gen test..

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 08 August 2013 at 11:26pm
It came in with that condition. Partly why it made the journey.

Yep have the gear to re bias it :)


Posted By: JayeJSAV
Date Posted: 10 August 2013 at 2:49am
Sigh, this is going to become "one of those" repair jobs. If it isn't already!

Replaced several parts now, out of 12 output transistors, 7 were short circuit...
The 2 x 2SA5002 and 1943's had popped open circuit, and after replacing all the burned resistors, I have.......

Square one!!!!! Back again.

Now concentrating on the power side of the board. It still sticks in protect, but the MJE350 is getting quite warm quite quickly. It was warm before, however I didn't notice it to be this hot.

My word, with even a sniff of a service manual I could be eating donuts whilst it soak tested and I watched NCIS. However, I'm off to the bar to bathe my brain in jäger in the hope I will have a top idea, whilst some weirdo comes in and holds a dimly lit lamp above my head.


Posted By: Tan-2
Date Posted: 10 August 2013 at 10:40am
Sometimes we get them pain in the butt repair's that have us burning the midnight oil...it's good to take some stress free time out.

Have you measured voltage at the o/p in case there's high offset?  even after replacement's have been fitted there still might be a leaky, o/c or s/c part, them sneaky diodes or even them small short circuit trannies within it's I-limiting circuit will act up.. that mje350 would under stress from heating up this would be around it's vas stage or bias circuit.. 

I've a few repairs waiting in the work shop so it's grab a coffee time/food offering followed by the joyful comments from 'joe' public.......ie, our amp starting smoking, mmm that can't be good for it's health!


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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 12 August 2013 at 4:01am
So, lots of stuff replaced, done all the big resistors, cause they all showed signs of scorching, and one had a broken leg too. Just did a power up test now after those replacements (couldn't swap out the MJE350 cause Farnell missed it off the order), and instead it just decided to blow that and take out my plug fuse. quite a few darkened resistors on the power supply board also, so going to change those too.

I wish this guy had just said "I'll replace it", although I am looking forward to the happy face when I've completed it, even if it is a full rebuild! :(


Posted By: Tan-2
Date Posted: 12 August 2013 at 8:53am
It's looking like a psu and stage rebuild on the cards ... Just hope that none of the replacement output devices have not been damaged when that primary fuse blow.
Try hifi engine and see if service info is there you might be lucky there or it will be the case of long hours to solve this mess.. Some up load pics would be handy here so we can see things as last link did not work.



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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 12 August 2013 at 2:02pm
Hifi engine?


Posted By: Tan-2
Date Posted: 12 August 2013 at 5:45pm
It's a site to look for schematic's..

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 12 August 2013 at 11:22pm
ooooooo :)


Posted By: JayeJSAV
Date Posted: 13 August 2013 at 5:12am
Ooooohhhhh kayyyyy

So, after repairing the power supply, I now have a nice pair of rails at +18v and -18v, and another pair at +70v and -70v. Before, I was getting a ripply +16 and -19, and then +60 and -78.

Bearing in mind that I have replaced with identical components (no alternative swap outs needed, all readily available), and that I have no kind of diagram at all, I don't even think one exists, I am hoping that they are correct.

On the photo, you can see the runs of resistors, all off a common track, feeding into one output device each. Those are the ones which were scorched, as well as the MJE350, and 340's. On magnification on the bench, I found some cracked diodes too, as well as bulging capacitors.

So I've replaced the 7 faulty output transistors, the other cracked components, and a couple of suspect ones (near by the ones which were damaged, not scorched as such but more discoloured). As they were mostly 1/4w resistors, I thought I may as well. Checked board for any stray solder and flux as per usual, and connected it back to the power supply. (After discharging PSU Caps).

Power up time!

1) Smoke.
2) 0.15 ohm resistors (at inner most side of white blocks - 5W), glowing...
3) I'm sat in bed writing this and picking their casings out of my hair.

So, tomorrow, test PSU post explosion.... and I have decided that as I have no information whatsoever, and the client STILL wants it fixing, despite rising costs, the only way forward is a complete rebuild of that channel.

I would have done some tests on it to get more info, however it blew up.

Here's a link to that picture, and hey guys, it works!!






Posted By: JayeJSAV
Date Posted: 13 August 2013 at 5:50am
Well after not sleeping yet and googling about, I found a spec sheet for it,  but that is literally it.

I've also seen it called a Cave CV4000 but apart from that, this amp doesn't seem to have any information at all. http://www.satsol.co.uk/impact/ProductInfo/J01953/J01953.pdf" rel="nofollow - http://www.satsol.co.uk/impact/ProductInfo/J01953/J01953.pdf


Posted By: Tan-2
Date Posted: 13 August 2013 at 9:12am
It's going to be a real testing time this repair and like you say, cost is creeping up.. Now that you've got the knackered channel out the way and using the working side for reference voltages that way you have something to go with.
It would of been best to replace all o/ps due to stress as working with a mix of replacements and old ones may see this unit back on your bench and a red faced client...

Here's the thing instead of reaching for that hammer to get the stress out as it may seem you can't see the wood through the trees so to speak.. Grab your meter and carry out cold resistance mesurements between the pcb's plus when powering up said faulty side using limiting resistors in the ht rails that way it would give you time to carry out ref points instead of cooking breakfast on the heating parts...
Do you have a variac with limiter that would aid running things up instead of slamming power on and watch the fire works happen...

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 13 August 2013 at 2:25pm
I don't, but I am still adding things to my bench as I go along.

Thing is, I am wary of applying the working side to the amp in case the psu isn't kicking out the right voltages, (bearing in mind nothing is labelled as to what it gives out, just VL and VH for low and high voltage).

I'm off for some bacon and components. Not necessarily in that order :)


Posted By: Tan-2
Date Posted: 13 August 2013 at 4:13pm
Your need to run the good channel to get a clear line of volts for ref point.. The Lv line would be running op-amps/ led display, there should be a feed to relay, fan circuit per say.. Even using 47 ohm say 40w or more in the ht rail would give time to get some voltages down.


The working side will be the only clue here to see how volt lines such as long tail in put transistors or if its op/amp in put circuit followed by vas stage driver and o/p end.

A quick limiter is the old lamp in the mains plug trick this acts as a limiter via glowing bright indicates a short some where and you might have to use to 100w bulbs.. The trusty lamp limiter as served me well...



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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: Tan-2
Date Posted: 14 August 2013 at 7:06pm
So was it a scrap it job due to cost or more time and parts to rebuild?

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 14 August 2013 at 10:19pm
Rebuild :/


Posted By: ceharden
Date Posted: 15 August 2013 at 12:51am
Originally posted by Tan-2 Tan-2 wrote:


A quick limiter is the old lamp in the mains plug trick this acts as a limiter via glowing bright indicates a short some where and you might have to use to 100w bulbs.. The trusty lamp limiter as served me well...



+lots!

This is an incredibly useful piece of test equipment.  It will generally allow you to fire up a piece of suspect equipment and determine if it's going to do serious damage if you give it full mains.  Quite often once the PSU caps have all charged, a fault-free amp will run with no-load even with the lamp inline.  If you power it up and the lamp stays bright, you know that there is still a fault to look for.

As well as one in a mains lead (with bypass switch), I also have a lamp on flying leads which I can insert into circuits instead of fuses etc.


Posted By: Tan-2
Date Posted: 15 August 2013 at 6:42pm
JayeJsav.... after looking at the photo it's a straight forwards amplifier module with signal transistor in put pair etc etc.. Now that you've got the psu working run up the working channel to determine volts at given points also take note of current draw and bias volts over the o/p emitter resistors.

Things can take longer with out a handy schematic but with some time most amps are common to solve.  


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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 16 August 2013 at 12:07am
Having a nightmare with hires on A-Level night, plus trying not to kill too many kids on the roads.....

Be back on it this weekend for some more midnight oil burning, with Jagerbomb aftertaste....

Thanks again guys :)


Posted By: Tan-2
Date Posted: 03 September 2013 at 8:07pm
How did you get on with amp in the end?  

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 03 September 2013 at 8:16pm
Stripped board back, as before, but been so busy on installs for freshers that I've not been at it since!


Posted By: CHAMPION
Date Posted: 04 September 2013 at 10:25pm
Speak to Andy at Impact im sure he can dig out the manual

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Sticks n Stones


Posted By: cravings
Date Posted: 23 October 2013 at 1:45am
i have a cave audio cv4000 here with a fault too. it belongs to a friend, i said i'd have a quick look at it.

it doesn't power up, blew the T20A fuse straight away. bringing it up with a variac and light bulb in series gives a bright glow immediately and a mild burning smell even as i get to about 50v..

i think this one is beyond me really.

but fwiw the cv4000 seems to be the brooke model below yours, as in, it's got gaps for more output devices, where in the photos, yours is fully populated.


Posted By: Tan-2
Date Posted: 23 October 2013 at 8:46am
Cravings,  carry out some straight ward checks... remove the power supply plugs that feeds both modules now, replace that blown fuse.. next power up via doing this your testing the psu is ok.

next test o/p devices for short circuit which will be the case here then test driver transistors etc...

Glowing bulb is showing you that there is a short..

 


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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: cravings
Date Posted: 23 October 2013 at 7:07pm
thanks for tips..

right.. disconnected the 2 channel boards from the psu, up to 20v, glowing pretty brightly, no change with the boards disconnected there...

not a good sign really.


Posted By: JR.junior
Date Posted: 23 October 2013 at 7:24pm
have you checked bridge rectifier?


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Support the scoop technology, larger mouth plays louder!


Posted By: cravings
Date Posted: 23 October 2013 at 7:31pm
yeah, went over all of them yesterday with the diode test on a meter... all as expected.


Posted By: Tan-2
Date Posted: 23 October 2013 at 10:21pm
Check the ac voltage on the transformer secondary tapings

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: cravings
Date Posted: 23 October 2013 at 10:47pm
while bringing it up? i'm worried to bring it up high at all...


Posted By: kedwardsleisure
Date Posted: 23 October 2013 at 10:55pm
ok, disconnect all loads from the transformer and see what the current's like then.

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Kevin

North Staffordshire



Posted By: cravings
Date Posted: 23 October 2013 at 11:29pm
hmm... instantly the same. so that just leaves the transformer.. and there's a board with a relay, and 4 x ntc thermistors and a few caps..

should that relay be clicking in before the transformer even starts to draw anything?


Posted By: cravings
Date Posted: 23 October 2013 at 11:39pm
just put a working CA18 on the same setup... light bulb not as bright. (just to prove to myself i'm not barking way up the wrong tree.)


Posted By: Tan-2
Date Posted: 23 October 2013 at 11:49pm
So if you have a working one use it as voltage refs to aid I solving the faulty one..

Such as high rail volts to the modules etc..
If no schematic is to hand then it'd down to solving circuit fault.. Ie s/c transistors etc..

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: cravings
Date Posted: 23 October 2013 at 11:52pm
nah, i have a crest audio CA18... just picked it as an amp with big inrush...

i don't have a working one of these.

cheers for tips though, much appreciated.

think i'll probably just hand it back to its owner tomorrow and admit defeat.

i have a hunch joebags from this forum may get to meet this amp soon though.


Posted By: Tan-2
Date Posted: 23 October 2013 at 11:55pm
Power Amps can be broken down in to stages check psu then cold check faulty modules next power them on lower rails or use limiter resistors in each ht supply rails to save more damage happening.


Start at the in stage then move a long vas stage then out puts.

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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: JayeJSAV
Date Posted: 24 October 2013 at 1:19am
Blimey I was wondering what all the notifications were about. In my case, I've backburnered this now cause I've got making money to do! :( step one. Blown up fire alarm repair!


Posted By: Tan-2
Date Posted: 24 October 2013 at 8:58am
Yes, it's sparked a second topic about these amplifiers.. Still we need to fill the wallet up!



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Logic will get you from A to B. Imagination will take you everywhere.


Posted By: kanks
Date Posted: 24 October 2013 at 4:47pm
Test the transformer by using a neon light bulb and a 9v battery.

You can test for a shorted winding with a neon bulb connected to one winding and a small battery one the another. You connect the battery to a winding and release this causes a kick to be generated at the other windings and will light your neon lamp for a second (just like and ignition coil). If there is a shorted winding the short will consume the generated current and the lamp will remain dead.

This needs the transformer out of circuit.

Edit to correct a mistake.


Posted By: cravings
Date Posted: 24 October 2013 at 4:56pm
this sounds very useful and i appreciate it and will definitely note that advice for future... but this amp has been boxed up and i'm returning it to its owner right now.

i made no promise to him to repair it, but i was curious to check it out. hopefully someone else can sort it out for him.

thanks all.

back to the brooke amp now :)


Posted By: kanks
Date Posted: 24 October 2013 at 5:43pm
When I learned it I got an old transformer to test the setup. your bulb (think it works best on the high side winding cant remember) connected to a winding and connect your battery for a sec to the other and release the bulb will flash. now pass a piece of wire around it and connect it to itself to create a shorted turn. Try again now the bulb wont flash as the shorted turn burns up the energy.

And back the the broke brooke


Posted By: Joebags
Date Posted: 18 December 2013 at 1:16pm
Smile Just came across this post now. Yep have it on the bench at the moment.

Seems like the transformer has some shorted windings. I disconnected the output modules and the power supply board and brought the voltage up with a variac and light bulb limiter and she glows like the north star!




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Wherever you go, there you are.


Posted By: cravings
Date Posted: 18 December 2013 at 3:12pm
yeah. that's what i was thinking.. but i thought that would be fairly unusual..


Posted By: Joebags
Date Posted: 18 December 2013 at 4:22pm
Not the most common problem but it does happen. I've emailed Brooke amplifiers to see if they do a replacement. Might be too costly to repair but I'll see if they get back in touch and take it from there.

 


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Wherever you go, there you are.


Posted By: Joebags
Date Posted: 18 December 2013 at 4:24pm
Just got an email back there. The amp has been discontinued for 4 years and they don't carry spares.Unhappy


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Wherever you go, there you are.


Posted By: cravings
Date Posted: 18 December 2013 at 5:12pm
it's not a brilliant amp but it has a fair bit of grunt...

they were sold that amp by someone in india who built them a sound system. he gave them a pair of single 18" reflex bins with p-audio something (sd18 maybe) in them, and a pair of double 15" boxes with 2 p-audio sn15b and a fake jbl backplate with random crossover, and a huge 2" p-audio horn with a 1" p-audio pa-26 or something on it.. and the one amp, and just told them to join it all up.

i've been giving them a crossover and a second amp though, so mostly that amp has just done the single 18s..

i'm going to see if i can help that system a bit. they don't need anything fancy, but i think losing the passing xover, fitting 2" comps on the horns, and maybe doing a bit with some other passive crossovers i have should make it a bit better...

shame about the amp though. how many taps are there off the xtformer?


Posted By: Joebags
Date Posted: 18 December 2013 at 5:30pm
Just put it away. I'll have a look in the morning. I'll let you know.


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Wherever you go, there you are.


Posted By: Joebags
Date Posted: 14 January 2014 at 10:59am
I took some photos here of the transformer wiring.

http://www.flickr.com/photos/33203633@N04/.

Primary is

Blue(245v)  Red(230v)  Red (0v)

Secondary is

Yellow (18v)  Black (0v)  Yellow (18v)

Green (0v)  Green (22.5v)

Red (92v) White (46v)   Black (0v)  White (46v)  Red (92v)

Regards

Joe


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Wherever you go, there you are.



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