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You are welcome Nicolaas!
We kunnen dit ook in het Nederlands voortzetten, but for the B&O community we’ll continue in English.Isopropyl: yes, if you have the 96% alcohol from the pharmacy, it will do. For some parts of the cleaning I dip earths in the alcohol to rub the foam dirt away. For the surface of PCB’s (printplaten) ~I dip a small (soft) toothbrush in the alcohol and gently brush the PCB.
Yes, this type of damage on the copper traces can already cause the malfunction.
If you experience bad contact of the RCA connector, I would check this:
- The RCA connector has a flat nut on the bottom side of PCB05 (see picture). You will have to remove the cone cover on the top/point of the foot to get access. If you get there, check if the nut is still tight.
- What I have also seen, is that the foam dirt was sitting on PCB06 (see picture). This PCB connects PCB05 and all electronics inside the alu casing. It therefore also influences the auto stand-by function. So check if this one is dirty too and clean it if necessary.
BeoLab Penta; yes they are great!
Hi Nicolaas,
Good that you post here and share what you have already seen.
As I can see from your picture, the deteriorated foam has definitely done ‘its work’. Especially on the right side of your picture, one can see that the two copper tracks have been damaged. The foam ‘eats’ the tracks away (like bite marks in the traces), and this in many cases causes the Auto stand-by to not be activated or to switch back and forth continuously.
Here’s my suggestion
I t could be there are also other problems, but I would start with this.
- Remove the Amplifier & Power Supply panel from the alu casing. Do the same with the speaker panel. Be careful. The speaker panel has one cable and connector connected to the amplifier side. And the Amplifier/Power Supply has three cable connectors that connect to the botttom of the alu casing.
- Remove all the foam particles from all places where you see them. This can be a time consuming work, because it can be everywhere. Make sure you clean it away from PCB’s, connectors, components, … You can use isopropyl alcohol to get the sticky parts away.
- When done, create a bypass as shown in the picture underneath.
When this is all done, put all parts back in the alu casing and reconnect. Power up the BeoLab, put an audio signal to the PL or RCA input and check if the auto stand-by turns on.
Let us know the outcome.
By the way, are you Dutch?Today I tried starting the comparison measurements. As a reference / working speaker I wanted to use another BeoLab 8000 with serial 16xx xxxx. But I found out that the PCB layout of components is slightly different than the trouble BeoLab I am working on (13xx xxxx), and from the PCB02 drawing I have from the Service manual.
To show the difference: first the drawing of PCB02 I have from the Service Manual, and underneath a picture of PCB02 from the 16xx xxxx speaker I wanted to use for comparison.
IC1 is still clear, but I am not sure about the position of C75, R136, and TR16.
Question
- Could you help me find where these components are, or maybe you have a visual layout of this PCB02 version?
Thanks again Keith! I hoped for a positive result with IC1, but I took into account that this would not be the trouble component. Nevertheless, we have come so far (at least in excluding trouble causes), so I will not give up.
Next step
Like you suggest, I will continue with continuity testing. To make sure I am looking at the right components to check …Question
Could you pleasde indicate to me, which components I should check, with the reference of the scheme (below) of the suspect area you posted before in this thread? (Take it as the way it takes the least time for you; either the components to check, or the ones I shouldn’t)
Thanks for your patience with me Keith. I am still learning, but I get this one.
Here’s the new measurements with: the negative lead of the multimeter on Pin 2 of P2 for ground, and the positive lead to Leg 4 and Leg 8 of IC1.
Here’s the results of measuring TR14 at Base, after removing R136.
Curious to learn what the results mean.
R136 removed.
@Keith: thanks, I guess I misunderstood.
So I re-measured with the multimeter in DC voltage.
Also, I did the same measurement with a speaker that switches correctly on the RCA/Line-in.
This is what you meant?
@Glitch: Thanks for your input and especially the visualization. This helps understand what to look for. So I will check again.
@Keith: Also thanks a lot!
TR14, TR16 & TR17
In the meantime I measured what you suggested. Since I do not have an oscilloscope, I used a multimeter (Voltcraft VC130-1), in diode/continuity mode. IO found out that the direction of TR16 on my PCB is 90 degrees different than the layout in the Service Manual. But I assumed the Base to still be the left leg of the two next to each other.
You can see the results below. In all measurements, no continuity signal but a value measured.
Measuring at TR16 with & without signal on RCA, the relay switched on. With audio signal on the RCA, music was also there.Additional
In the schematics of PCB02, I read that IC1 should measure +15v at leg 8, and -15v at leg 4.
- I measured 29v.
As IC should also measure +15v at leg 8, and -15v at leg 4, I checked that one too.
- Also 29v.
Question:
- What does this mean to you?
- In the meantime I have also received a new IC1. Do you suggest to execute the replacement, or do you have another suggestion?
Though B&O uses an 8-pin DIN connector, for this purpose you can use a 5-pin DIN connector, using only 3 pins.
It is all about connecting a cable with 3 leads to the right pins, for getting the stereo signal from your WiiM in to the BS9000.
The 3 leads are: (picture show male DIN connector from the back/solder side, or female from the front side)
- Gnd to pin 2
- Right channel to pin 4
- Left channel to pin 1
