Allen & Heath Saber... Again!

[psb_87]

There's several threads about this particular desk, but AFAIK none actually about repairing the faults that mine has. 

There's 4 main faults that I've found so far with the console which are spread out over the various channels.  These are:

-Gain at max triggers Mute LED
-Peak LED stuck
-Mute switch not functioning
-Mute LED stuck
-Oscillation and no audio on master L & R &

I've attached a PDF with a table of faults I've found for each channel.

The schematics and service manual can be found here:
http://www.allen-heath.com/ahproducts/saber-mk1/#tab4

If anyone is crazy and wants to take on this mammoth task of helping me repair the console, that would very much be appreciated.

Thanks in advance!

 

[pucho812]

There's several threads about this particular desk, but AFAIK none actually about repairing the faults that mine has. 

There's 4 main faults that I've found so far with the console which are spread out over the various channels.  These are:

-Gain at max triggers Mute LED
-Peak LED stuck
-Mute switch not functioning
-Mute LED stuck
-Oscillation and no audio on master L & R &

I've attached a PDF with a table of faults I've found for each channel.

The schematics and service manual can be found here:
http://www.allen-heath.com/ahproducts/saber-mk1/#tab4

If anyone is crazy and wants to take on this mammoth task of helping me repair the console, that would very much be appreciated.

Thanks in advance!

when was the last time if any, did you recap any of the modules or PSU or any part of the console?

 

[psb_87]

when was the last time if any, did you recap any of the modules or PSU or any part of the console?

Hi pucho, I haven't had the desk long and haven't got round to recapping anything yet.  I did replace 1 cap on both master L & R cards (C37) as there was some discolouration around it.  I replaced it with the exact same value as the original, and paying attention to the polarity of course.

I have also replaced IC1,2,3 & 4 on the master L & R cards; I put sockets and just popped in some new chips (TL072s and 1x5532, same as the original) just in case these were fried.  I will eventually put in some nicer chips once I have the desk working stock again.

R92,R94,R95 & R96 were also fried so I replaced them on the master R card, then R92 & R95 on the master L card.  I thought if resistors are being fried then there must be some chips that have gone, which is why I replaced the ICs mentioned above.

On the monitor card I replaced a couple of chips and transistors as well, but the monitor module seems to be functioning as intended.

Do you suspect it's the caps that are causing the various problems across the board?  I do not know the history of the desk before it was in my hands, all I know is that it was kept in storage for a couple of years and more than likely got exposed to moisture.  It looks like it's had some of the caps replaced recently before I got it, but as there's no way of knowing for sure I will try a recap. 

I will just recap the master section for now, can i bump up the values? If so, what can I use?  I really am not sure about the theory of electronics but I can follow instructions and solder very well.

Thanks again

 

[scott2000]

Hi pucho, I haven't had the desk long and haven't got round to recapping anything yet.  I did replace 1 cap on both master L & R cards (C37) as there was some discolouration around it.  I replaced it with the exact same value as the original, and paying attention to the polarity of course.

I have also replaced IC1,2,3 & 4 on the master L & R cards; I put sockets and just popped in some new chips (TL072s and 1x5532, same as the original) just in case these were fried.  I will eventually put in some nicer chips once I have the desk working stock again.

R92,R94,R95 & R96 were also fried so I replaced them on the master R card, then R92 & R95 on the master L card.  I thought if resistors are being fried then there must be some chips that have gone, which is why I replaced the ICs mentioned above.

On the monitor card I replaced a couple of chips and transistors as well, but the monitor module seems to be functioning as intended.

Do you suspect it's the caps that are causing the various problems across the board?  I do not know the history of the desk before it was in my hands, all I know is that it was kept in storage for a couple of years and more than likely got exposed to moisture.  It looks like it's had some of the caps replaced recently before I got it, but as there's no way of knowing for sure I will try a recap. 

I will just recap the master section for now, can i bump up the values? If so, what can I use?  I really am not sure about the theory of electronics but I can follow instructions and solder very well.

Thanks again

I would probably try testing things for obvious failure. Sometimes you can risk damage to something while replacing components and testing would justify the risk to reward. Diodes ,resistors,caps and transistors can be checked pretty easily after the obvious bad connections,missing or misplaced jumpers,solder joints etc......and you won't run any additional risks of possibly damaging any new component you may decide to put in......

Definitely sounds like there's an issue with the muting circuit/s

Good luck!

 

[pucho812]

before we replace anything.  Get yours self a capacitor wizard.  They are a simple capacitor tester that you can measure capacitors while in circuit. It's pretty idiot proof and can tell you if the cap is good, or bad with a wide maybe area.  It's simple and easy and can easily tell you what is what.
They run anywhere from 90 dollars used and 180 new. Totally worth it.

 

[psb_87]

I would probably try testing things for obvious failure. Sometimes you can risk damage to something while replacing components and testing would justify the risk to reward. Diodes ,resistors,caps and transistors can be checked pretty easily after the obvious bad connections,missing or misplaced jumpers,solder joints etc......and you won't run any additional risks of possibly damaging any new component you may decide to put in......

Definitely sounds like there's an issue with the muting circuit/s

Good luck!

Hey thanks a lot for your encouragement.  How would I check those components without removing them from the PCB first?

 

[psb_87]

before we replace anything.  Get yours self a capacitor wizard.  They are a simple capacitor tester that you can measure capacitors while in circuit. It's pretty idiot proof and can tell you if the cap is good, or bad with a wide maybe area.  It's simple and easy and can easily tell you what is what.
They run anywhere from 90 dollars used and 180 new. Totally worth it.

Thanks a lot for the tip, I would love to get one of those capacitor wizards! Unfortunately they're quite pricey in the UK... for the same price I suspect I could get the desk repaired professionally... which is what I might end up doing anyway.  I figured that it wouldn't take too long to replace the caps on the master module and I could upgrade the caps at the same time.  Should I just order the exact same values as what's already installed or should I be upping the values on any of the capacitors?  I know that the current capacitors are rated at only 85 degrees.... so I could definitely up that to 110 or something, but how about the micro farads and voltage ratings?

Again any help is much appreciated

 

[musika]

Unfortunately they're quite pricey in the UK... for the same price I suspect I could get the desk repaired professionally...

At that rate, I'd go for it.... but in my area of the world, a reputable audio tech would give you an hour (maybe 2) for that price. And that's not gonna get you too far.

If you know someone who is good at soldering and has recapped console modules in the past, it may be a good idea to ask them to do a mass replacement of your caps for starters and then bring it to a pro to have go over the circuits.

JMHO (from experience).

 

[scott2000]

Hey thanks a lot for your encouragement.  How would I check those components without removing them from the PCB first?

https://www.ebay.com/itm/ViCi-DM4070-Digital-LCR-Meter-with-Free-Portable-Case/282707879240?epid=1348491992&hash=item41d2b3e548:g:8VsAAOSw-0xYdBBe

This works for testing component values in circuit quite well actually(just use different probes). It won't test for leaky caps (there are other ways with a multi meter) or ESR but, it will tell you if something is way out of tolerance or worse(and the larger percentage that are just fine )........which is usually good enough to get you up and running....

If you come across a bad component, remove at least a leg and recheck to make sure that it isn't reading goofy because it's in line with another component making it appear off. This will happen about 20% of the time for me.

A simple multimeter  can check for transistors and diodes using the diode function.

Continuity function will help much in many cases as well.....

Checking ac/dc is a must at some point......... especially in power supply regulation then to make sure everything is getting the voltages it's supposed to.......  Even works quite well in chasing down an ac sine wave and how it changes through the circuit...

Pretty big thing you are getting into. But, you already seem to know how to solder so, may as well pick up some reasoning along the way. You'll need more than solder skills when you get into upgrades/mods and to repair any damage that may happen down the road.

But having a Tech look at it is a great idea and you could at least know some of the issues to focus on..... But yes the cost may be out of reach sometimes.... if you think the desk can be repaired for the cost of the Cap Wizard (which I have to get for Christmas!!! Thanks Pucho!)....I'd be all over that option instead...

Or start reading the service manual (most helpful), become comfortable with the schematics(most necessary) and (after abstaining from alcohol and caffeine :-[ )start poking around (mind the dangers!)...... You never know.....

Good Luck!!

 

[psb_87]

https://www.ebay.com/itm/ViCi-DM4070-Digital-LCR-Meter-with-Free-Portable-Case/282707879240?epid=1348491992&hash=item41d2b3e548:g:8VsAAOSw-0xYdBBe

This works for testing component values in circuit quite well actually(just use different probes). It won't test for leaky caps (there are other ways with a multi meter) or ESR but, it will tell you if something is way out of tolerance or worse(and the larger percentage that are just fine )........which is usually good enough to get you up and running....

If you come across a bad component, remove at least a leg and recheck to make sure that it isn't reading goofy because it's in line with another component making it appear off. This will happen about 20% of the time for me.

A simple multimeter  can check for transistors and diodes using the diode function.

Continuity function will help much in many cases as well.....

Checking ac/dc is a must at some point......... especially in power supply regulation then to make sure everything is getting the voltages it's supposed to.......  Even works quite well in chasing down an ac sine wave and how it changes through the circuit...

Pretty big thing you are getting into. But, you already seem to know how to solder so, may as well pick up some reasoning along the way. You'll need more than solder skills when you get into upgrades/mods and to repair any damage that may happen down the road.

But having a Tech look at it is a great idea and you could at least know some of the issues to focus on..... But yes the cost may be out of reach sometimes.... if you think the desk can be repaired for the cost of the Cap Wizard (which I have to get for Christmas!!! Thanks Pucho!)....I'd be all over that option instead...

Or start reading the service manual (most helpful), become comfortable with the schematics(most necessary) and (after abstaining from alcohol and caffeine :-[ )start poking around (mind the dangers!)...... You never know.....

Good Luck!!

Hey thank you so much for all the detailed information, I know I still have loads to learn but I'm starting to get my head round things a little.

I've decided I'm going to go ahead and recap the master section, there's only around 13 caps per card so it won't take that long and I'm sure it's in need of new caps anyway.

If this doesn't solve the problem with the master section then I'll take it to a tech.

I just wanted to know if I should keep the stock values on all caps or if I should increase the values on some? If so, what would you suggest?

 

[scott2000]

.

If this doesn't solve the problem with the master section then I'll take it to a tech.

Hopefully new problems won't be created if you end up having to take it to someone. There's ALWAYS a chance you could accidentally damage something else that, although may not be the most difficult thing in the world for an experienced tech to fix, may be frustrating to you.

This is why I like to test first (risk to reward) and...... it's also nice to see where the problems are because it makes it easier to trace the issues to the related components and work from there...... If I knew nothing was wrong with the master section caps, I'd focus somewhere else..... maybe upgrade them later once the issues are sorted.....

But, you may get lucky...It does happen I'm guessing or else people wouldn't feel like doing it this way I suppose....

If you are set on recapping, just do a nice grade cap (Panasonic FR is what I've been using in most places and I think they are my new favs) and stick with the same values or bump the voltages a tiny if needed....

But to be clear, I don't think you are going about this the right way.... But I know how it is...... It's hard to not "do anything" and it feels like it can't hurt.....


Good Luck!!!

 

[psb_87]

Hopefully new problems won't be created if you end up having to take it to someone. There's ALWAYS a chance you could accidentally damage something else that, although may not be the most difficult thing in the world for an experienced tech to fix, may be frustrating to you.

This is why I like to test first (risk to reward) and...... it's also nice to see where the problems are because it makes it easier to trace the issues to the related components and work from there...... If I knew nothing was wrong with the master section caps, I'd focus somewhere else..... maybe upgrade them later once the issues are sorted.....

But, you may get lucky...It does happen I'm guessing or else people wouldn't feel like doing it this way I suppose....

If you are set on recapping, just do a nice grade cap (Panasonic FR is what I've been using in most places and I think they are my new favs) and stick with the same values or bump the voltages a tiny if needed....

But to be clear, I don't think you are going about this the right way.... But I know how it is...... It's hard to not "do anything" and it feels like it can't hurt.....


Good Luck!!!

Yeah I agree with you, I guess the main reason for doing it myself is because the nearest techs that would be able to service the desk are around 4 or 6 hours away from where I am... I've asked around and there's no-one here that has the know how with mixers.  So I would have the hassle of disassembling the desk, trying to fit it in my tiny car again (without scratching it or the car up) risk more damage in the process and then pay £100 extra in fuel costs.  Then I would need to wait a couple of months or more for the work to be done, and then go and get pick it up and go through the reverse process again! Though it would be worth it to get the desk up and running properly, I just don't have enough cash to pay for the repair plus the fuel at the moment.

So there's that, plus my own pride.  I've always been one to fix things myself.  I like the learning experience and it interests me.

Famous last words hey?

Anyway thank-you for your excellent replies to my post, I really appreciate you taking the time to do so.

 

[scott2000]

Yeah I agree with you, I guess the main reason for doing it myself is because the nearest techs that would be able to service the desk are around 4 or 6 hours away from where I am... I've asked around and there's no-one here that has the know how with mixers.  So I would have the hassle of disassembling the desk, trying to fit it in my tiny car again (without scratching it or the car up) risk more damage in the process and then pay £100 extra in fuel costs.  Then I would need to wait a couple of months or more for the work to be done, and then go and get pick it up and go through the reverse process again! Though it would be worth it to get the desk up and running properly, I just don't have enough cash to pay for the repair plus the fuel at the moment.

So there's that, plus my own pride.  I've always been one to fix things myself.  I like the learning experience and it interests me.

Famous last words hey?

Anyway thank-you for your excellent replies to my post, I really appreciate you taking the time to do so.

Sure!!

Just work on getting you some testing meters for the future. They're never a questionable thing to have.......Besides...... . It's much easier when the horse is out front.....

Good Luck!

 

[psb_87]

So I replaced all the caps with Philips FC on the master L & R modules.  Still no luck

All the chips and electrolytic caps have been replaced on those modules now, there's only the resistors and a few non-polarised caps as well as 5 transistors that have not been replaced.  If it is a component fault, I can't imagine it being anything but the transistors causing the problem now.  Thoughts?

I've checked for shorts and cold solder joints, reflowed most of the joints, replaced the wires going to the fader, checked the fader itself.  There is nothing else that I can think of other than it possibly being something wrong with the monitor module which is on a separate card?

There's power going to the cards, though it doesn't seem there is power reaching the top part of each card where the master AUX controls are.  I think this because the LEDs are not lit, though only some of them will light on the bottom section of the modules too.

At this stage I really need someone who knows how to use a scope to take a look and find out what's going on, unless anyone here has any more ideas?

 

[scott2000]

So I replaced all the caps with Philips FC on the master L & R modules.  Still no luck

All the chips and electrolytic caps have been replaced on those modules now, there's only the resistors and a few non-polarised caps as well as 5 transistors that have not been replaced.  If it is a component fault, I can't imagine it being anything but the transistors causing the problem now.  Thoughts?

I've checked for shorts and cold solder joints, reflowed most of the joints, replaced the wires going to the fader, checked the fader itself.  There is nothing else that I can think of other than it possibly being something wrong with the monitor module which is on a separate card?

There's power going to the cards, though it doesn't seem there is power reaching the top part of each card where the master AUX controls are.  I think this because the LEDs are not lit, though only some of them will light on the bottom section of the modules too.

At this stage I really need someone who knows how to use a scope to take a look and find out what's going on, unless anyone here has any more ideas?

You have to get some kind of test metering. It could be as simple as a bad capacitor or resistor and you'll never know unless you can test them.

Do you at least have a multimeter? You could pretty much verify the transistors and diodes are ok in circuit with that.......Pretty much.... You may end up having to pull them to double check......

It's a big project . You need some tools or someone who has them......Chances are You can get by without a scope..........


And those were Panasonic FC? Hopefully you got them from a reputable source....I had some from a surplus store and some were bad even nos......... I put them in circuit without testing and it wasted some time figuring out why I had problems.....

Good Luck!

 

[psb_87]

You have to get some kind of test metering. It could be as simple as a bad capacitor or resistor and you'll never know unless you can test them.

Do you at least have a multimeter? You could pretty much verify the transistors and diodes are ok in circuit with that.......Pretty much.... You may end up having to pull them to double check......

It's a big project . You need some tools or someone who has them......Chances are You can get by without a scope..........


And those were Panasonic FC? Hopefully you got them from a reputable source....I had some from a surplus store and some were bad even nos......... I put them in circuit without testing and it wasted some time figuring out why I had problems.....

Good Luck!

Hi yes I bought the FC caps from a reputable seller (RS Components) and yes I do have a multi-meter.  I've tried testing the transistors in the circuit and they check out, but since there's only 5 per card I will pull them out and test them properly for accuracy.

There were some resistors which were burnt out which I replaced.  I guess some more resistors could have gone bad without any visible signs, but theres a tonne of resistors in each card and I don't fancy/testing and replacing them all.  I might replace all of the 22k feed resistors next to the ribbon connector cable as this is where the fried ones were. 

I'm gradually learning how the circuit works by studying the schematics, but it's still a bit of a mystery to me.

Thanks for your help!

 

[psb_87]

And those were Panasonic FC? Hopefully you got them from a reputable source....I had some from a surplus store and some were bad even nos......... I put them in circuit without testing and it wasted some time figuring out why I had problems.....

Good Luck!

Sorry yes, Panasonic!

 

[scott2000]

Hi yes I bought the FC caps from a reputable seller (RS Components)

Great!

I've tried testing the transistors in the circuit and they check out, but since there's only 5 per card I will pull them out and test them properly for accuracy.

Probably no need to...Pull them if they read bad is what I do....

  I guess some more resistors could have gone bad without any visible signs, but theres a tonne of resistors in each card and I don't fancy/testing and replacing them all.  I might replace all of the 22k feed resistors next to the ribbon connector cable as this is where the fried ones were. 

Yes! Any component can be bad and not "look" like it is...... It's not hard to test all resistors in circuit....Probably test them all very quickly if your meter lets you..... It's the easiest part of anything imo...... definitely easier than desoldering and soldering.....

I'm gradually learning how the circuit works by studying the schematics, but it's still a bit of a mystery to me.

Just focus on finding the broken parts right now...... By tracing the schematics while doing this, you'll pick up more of the pieces on how things work.....

Unless you want to dive right in to the theory but, you probably want to get some sound coming out and you need to find what's not working to do this. Of course knowing how the circuit works will help tremendously but, it's not as easy as figuring out how to troubleshoot bad components......

You may end up needing more than trouble shooting skills if they don't work but, most of the time you'll find the problem......

Good luck!!!!!

 

[psb_87]

Yes! Any component can be bad and not "look" like it is...... It's not hard to test all resistors in circuit....Probably test them all very quickly if your meter lets you..... It's the easiest part of anything imo...... definitely easier than desoldering and soldering.....

Okay, so would I do this the same way that I would test a resistor out of a circuit? If so, that's easy.

 

[scott2000]

Okay, so would I do this the same way that I would test a resistor out of a circuit? If so, that's easy.

Yes

If you get some weird readings , and you will sometimes , pull a leg and double check.........

Not sure how many meters are good at this (some are pretty bad, the one LCR I mentioned earlier is pretty good) but, I'd guess a regular multimeter will do fine.....

The service manual is pretty big....Glancing through, page 54 seems to start getting into some checks.....That audio mute element section and the mute processor is interesting.....

Hopefully you can get some more information put together. Your symptoms are pretty vague to me but they do seem to point to a common area that seems to be creating issues.

You'll want to make sure your power supply is functioning right at some point too.....

Good luck!!