Powerhouse Horizon 1208 Powered Mixer - No speaker output

[dicky96]

Hi guys
I have this Powerhouse Horizon 1208 here.

The mixer appears to work - I get output on the headphone socket, but no output on the speakers. The speakers are tested working, I don't get any hiss, power on 'bump', nothing, nada

Problem is I don't know if I have set all the controls correctly so this could be a phantom fault AKA user error or it could be faulty. I tried to find a user manual but couldn't find a download that actually worked.

I made a quick 2 mins YT video to show what is happening/not happening - hopefully someone could check that out and let me know if this is faulty or not.

https://youtu.be/4FfrzLJv1uU

Cheers
Rich

[petehall347]

first off plug into channels 1 and 2 ..pan one left and other right .. m1 m2 might be for monitors
are there any switches on the back ? and any chance of pics to see the switches ?

[dicky96]

Hi petehall

Here are some pics

The mixer is supposed to have some fault, but Domingo at Powersound speaks only 'some' English I only speak 'some' Spanish so we generally communicate in a mixture of Spanglish and gesticulation.

As I understood what he was saying it has some problem with the speaker output on one channel, but that could be a mistranslation

I will try channel 1 & 2 as you suggest.

[petehall347]

you could also try plugging into line ins . and maybe the pgm button needs pressing to route the signal to the amp .
not sure what the footswitch is about . maybe just for effects . make sure nothing is jammed in it anyway .

[petehall347]

another thing is the mixer i have been working on was doing strange things with the led,s .turned out some were bad so changed them all .
oh and another simple mistake is not turning the speaker plugs to lock them in place .

[dicky96]

Hi Pete
I'm not sure what you meant by plugging into Line In - that's where I have my two Phono to 6.3mm Mono Jacks plugged in on stereo channel M1

If I press the 'Listen' button in, on M1 channel, then the LED bargraph responds regardless of the Red Left/Right slider position - even if they are set to zero

When 'Listen' is out I then have control of the LED bargraph using the M1 volume slider and the Red Left/Right volume sliders. So the above video is with 'Listen' button out

Yeah I know how to plug in a Speakon connector but thanks for mentioning it

On the Speakon connectors my speaker wires are connected to +1/-1 which would be the 'normal' way to connect them. The fact I don't get any turn on 'bump' or hiss on the speakers makes me think the amp just isn't running though it could have a circuit to stop the 'bump'

I think the pgm button is for the programmable reverb but yeah I'll give it a go

I guess the other thing is to open it up - possibly it is obvious where the audio out feeds from the mixer section to the PA section and I could use my scope, or just inject audio there from another mixer (non powered) that I have.

[petehall347]

looks like aux ins next to record ? if there is it should bypass the channels . although signals must be getting to the main sliders or the led.s wouldn't light .
pgm is normally out to speakers .
be easier if there is a manual for it .
it should be pretty simple and modular inside like all my mixers .

[dicky96]

I found the fault on one of the Amplifiers. It is on the board that switches the -44V/-88V as this is a class G amplifier. Basically i had fuses blown on -44V/-88V on the left channel, plus two short circuit diodes (1N5404 + BAT20) and an iffy looking transistor on that board. At first I thought the voltage switching transistors were short, but they are not, they test OK on my Peak DCA55, it was the diodes short.

The iffy looking transistor is B1186A shows as a 'PNP Digital Transistor' on my Peak DCA55 but the datasheet says it is just a regular PNP power transistor. This is the driver for the voltage rail switching transistors on the negative side. I'll ask about that in the general electronics/component forum section

I still didn't determine why I had no audio but the customer said he did have audio that was bad on one channel so obviously he knows how to use the mixer and I don't LOL

Here is a video showing what I did to diagnose the fault if anyone is interested to watch

https://www.youtube.com/watch?v=XgZSxWMKuxc (part 1)
https://www.youtube.com/watch?v=kbPynpQefz8 (part 2 - the fault diagnosis)