Mackie SWA1501

[toddm]

You can see I had less than a volt (0.78V)on my speaker terminals. 25V seems awfully high in my opinion. I think you have more work to do.

From my last post all I have done is replace the 15V zeners to get the 16.45V closer to 15V. The sub has been working fine for the last 4 weeks.

[Enzo]

Fix those resistors and their zener diodes, and then we can talk about fixing the amp. The amp does not require a speaker load to function. ANd any DC voltage above a tiny bit is wrong.

[Anodyne Audio]

interchange them. D19 needs to go where D20 is and vice-versa

[Bigdrums]

I have a Mackie SRS1500 I'm trying to repair. The output is at -60VDC to the speaker, with no load and no input signal. I have noticed some other very strange voltages. For example at Q24 leg 1 is 69V, leg 3 is 68V, but leg 2 is -63V. But Q17 has -64V on all 3 legs, and Q19 is -60V all 3 legs. I've checked just about every componate and replaced the suspects with factory parts, namely: C9,Q3, Q9, C5, Q11. Curiously running up the variac, D26 flashes faster and faster as the voltage increases, and a clicking sound, appears to be inside C5, an box cap.

I tried to include the .pdf but no luck even though I have it on this computer. Someone clue me in here?
Edit Report

[Enzo]

Hi, Bigdrums, welcome to the place.

Please start a new thread for your Mackie SRS1500. You will get far better response than here at the end of a SWA1501 thread.

But for now, Q24 is not conducting. So the top end of it has the V+, and the bottom end winds up with V-. Untill current flows through it, no voltages will be dropped across the intervening resistors. Q17 has little to say in the matter.

Q19 is a limiter and is connected directly to that output bus which is sitting at -60, so so will Q19.

Pull Q24 and check it. If it is good, find out why the rest of hte circuit can;t pull down on its base to turn it omn.

[chickenwatt]

Hi Enzo, I am repairing a SWA1501 that was not givin full power because the high voltage rails were not conmutating, but before find the problem I measure an DC offset of 0.25volts at the output, I understand that this offset is controled by the green leds and the 3.3 volts 1 watt zeners but the service manual does not mention nothing to regulate dc offset, this is a design error in my perspective

[Appaloosa]

Thanks again Enzo. I will check all resistors and Zeners and be back. -thanks

[av.sorong]

r64 blow up

dear all,

I have 2 swa1501, but one is down. the woofer is blown again, again and again... I decided to replace with... Subwoofer tesla 15 inch double coil @4 ohm, first when i configured at 4 ohm, it sounds not too good, not a deep bass... But when i configured at 8 ohm i mean + to - at subwoofer pin, it sounds so good, deep bass execelent, but only 2 minutes... The R64 blown up and fuse 1 on the middle board blow too...

First may i ask ur help,

1. Why it happens?
2. do i just need to replace the r64? How ohm is it?
3. Is the fuse on the middle board is 250v 8a? Or must else?
4. What must i do/ replace/ modified, to use my sub tesla with swa1501 amplifier?

Thank's a lot before.

Sorry if my words bad, i am from indonesia.

andri angir.

[av.sorong]

R64

Thanks again Enzo. I will check all resistors and Zeners and be back. -thanks

dear all,

I have 2 swa1501, but one is down. the woofer is blown again, again and again... I decided to replace with... Subwoofer tesla 15 inch double coil @4 ohm, first when i configured at 4 ohm, it sounds not too good, not a deep bass... But when i configured at 8 ohm i mean + to - at subwoofer pin, it sounds so good, deep bass execelent, but only 2 minutes... The R64 blown up and fuse 1 on the middle board blow too...

First may i ask ur help,

1. Why it happens?
2. do i just need to replace the r64? How ohm is it?
3. Is the fuse on the middle board is 250v 8a? Or must else?
4. What must i do/ replace/ modified, to use my sub tesla with swa1501 amplifier?

Thank's a lot before.

Sorry if my words bad, i am from indonesia.

andri angir.

[J M Fahey]

The original subwoofer has a 12 ohm coil, you can never go below that.
Use a 16 ohm coil woofer.
Forget those dual coil ones which are meant for car or home theater audio, you need a Pro Sound unit.

[av.sorong]

16 ohm coil?

The original subwoofer has a 12 ohm coil, you can never go below that.
Use a 16 ohm coil woofer.
Forget those dual coil ones which are meant for car or home theater audio, you need a Pro Sound unit.

Dear sir,

is it more safe to use a 16 ohm coil rather than 12 ohm coil? Or can i use my 2 subwoofer tesla and bridge at 8 ohm, and then i bridge 2 sub at once? So it will be 16 ohm, is it okay for the sound and for the modul? And what should i do to repair my modul, r64 blown up. Should i change the q5 and 18 too?

i thank you so much for your help sir...

[J M Fahey]

Dear Sorong

is it more safe to use a 16 ohm coil rather than 12 ohm coil?

Yes, and is a standard impedance, so it's somewhat easier to find drivers .
*Or*: I suggest you talk with your speaker reconer and order a couple 16 ohm voice coils by mail from USA, then you recone it and have a spare just in case.
I think it's the cheapest (in the long run) and safest solution.
That power amp is *too* powerful, just like that.

Or can i use my 2 subwoofer tesla and bridge at 8 ohm, and then i bridge 2 sub at once? So it will be 16 ohm, is it okay for the sound and for the modul?

Maybe, but how/where will you mount the second woofer?

And what should i do to repair my modul, r64 blown up. Should i change the q5 and 18 too?

You will have to get an experienced technician, this power amp is tricky.
That subwoofer is killer, but too much on the edge of what can be done.
This is a 101 post thread where everything has been discussed about it, you have the schematic, hints, etc.
That power amp needs to be troubleshooted and will certainly have more bad parts than a resistor and a couple transistors.
Wish you the best of luck.

[av.sorong]

i have another swa1501

Dear Sorong

Yes, and is a standard impedance, so it's somewhat easier to find drivers .
*Or*: I suggest you talk with your speaker reconer and order a couple 16 ohm voice coils by mail from USA, then you recone it and have a spare just in case.
I think it's the cheapest (in the long run) and safest solution.
That power amp is *too* powerful, just like that.

Maybe, but how/where will you mount the second woofer?

You will have to get an experienced technician, this power amp is tricky.
That subwoofer is killer, but too much on the edge of what can be done.
This is a 101 post thread where everything has been discussed about it, you have the schematic, hints, etc.
That power amp needs to be troubleshooted and will certainly have more bad parts than a resistor and a couple transistors.
Wish you the best of luck.

Sir,

I have 2 swa1501, one is its modul totally burnt... I have sent to kairos as authorized service centre but almost 6 month no result....

So i plan to plant other tesla sub to empty swa box, it will be 2 boxes, with 1 filled with modul and sub, and other filled only with sub.

Sir, please make me sure, is it can be done and safe to sub and the modul if i did as above?

Thank you so much sir.

[J M Fahey]

Let me see if I understand (I may be wrong):
>You have TWO WA1501
>Both original woofers are burnt.
>One built-in power amp works perfectly, one is burnt.
>You have two Tesla SubWoofers .(Please post or link any datasheet about them).
They are dual-voice coil which can be wired for 8 ohms total per speaker.
>You will mount one woofer per cabinet, and devise some connection for the woofers to be in series, so the powwer amp sees 16 ohms.

Yes, it may work, it's reasonable.
You must ensure certain conditions
> Be *sure* they are 8 ohms each (DC resistance should be between 5 and 7 ohms)
> Add some new connector to each cabinet. I would play it safe and use a dual banana connector , color coded, say, red and black, so everything is "visible" and you can't plug anything else there, that's why I suggest to avoid Speakons , Plugs, etc. in this particular case.
>You should wire the passive woofer straight to the banana connector with the correct phase (+ to red).
> At the powered one, wire the power amp "hot" terminal to the Red banana; the black banana to the speaker's "+" terminal; the speaker's "-" terminal to ground as original.
> The Powered cabinet will not sound if the passive one is not connected to it, I like that.
> I *think* the passive cabinet remains adequately sealed even with the power module removed; but if not, cover the hole as you see fit.
Good luck.

[av.sorong]

that's right

Let me see if I understand (I may be wrong):
>You have TWO WA1501
>Both original woofers are burnt.
>One built-in power amp works perfectly, one is burnt.
>You have two Tesla SubWoofers .(Please post or link any datasheet about them).
They are dual-voice coil which can be wired for 8 ohms total per speaker.
>You will mount one woofer per cabinet, and devise some connection for the woofers to be in series, so the powwer amp sees 16 ohms.

Yes, it may work, it's reasonable.
You must ensure certain conditions
> Be *sure* they are 8 ohms each (DC resistance should be between 5 and 7 ohms)
> Add some new connector to each cabinet. I would play it safe and use a dual banana connector , color coded, say, red and black, so everything is "visible" and you can't plug anything else there, that's why I suggest to avoid Speakons , Plugs, etc. in this particular case.
>You should wire the passive woofer straight to the banana connector with the correct phase (+ to red).
> At the powered one, wire the power amp "hot" terminal to the Red banana; the black banana to the speaker's "+" terminal; the speaker's "-" terminal to ground as original.
> The Powered cabinet will not sound if the passive one is not connected to it, I like that.
> I *think* the passive cabinet remains adequately sealed even with the power module removed; but if not, cover the hole as you see fit.
Good luck.

Dear sir,

that is exactly right like you said sir, and all i plan to do is just right as your explaning.

Sir, i have no specs at all about tesla 15 inch dual coil @4 ohm.

I very hope after the modul repaired, it will be fine with my prediction.

Sir, do i wrong if i boost freq under 100hz about 6db? What is the maximum db input for swa1501?

Thank you a lot sir for your help.