Repair ZP120



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Hi Gruv2ths.
After i´m push play its still 15V at 36V testpoint?
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Hi Sotisg69,
Well if you’re original problem is gone but now you have a new problem, I would definitely resolder the pins of the new IC. Maybe take a magnifying glass and see if you have good solder flow on each pin, and more importantly make sure you have not bridged and pins with solder.
After that when you push play, make sure your 36V test point on the bottom of the power board goes from 15V to 36V.
If all that is ok, there is a pre-amp chip between the logic board and the power amp ICs. It has a mute pin that you can see if it is stuck. But it’s unlikely. More likely your already on the right track.
Hello gruve2ths excellent jobb back there.
I have a zp120 it goes flashing orange and white when play is pressed. I have changed the driver IC 14pin on the logic card and that broblem was solved internet connection and volume ok but still not get any sound from the speakers!! I'm not sure that i soldered all the pins from the new 14 pin IC on the logic board .... is there any chematic or can i measure it some way.
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Pdog,
You can take a radial leaded ceramic cap and touch its leads to the various ceramic cap leads while the noise is obvious and see if any of them seem to like the parallel capacitance and the noise is damped. Just a thought.
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Pdog,
What I meant was, look for cracked ceramic caps.
I have a spare logic board.
Will message you.
Gruv2ths,

I couldn't detect visually any cracks in the solder joints of caps on the logic board. I don't have the oscilloscope or skill to troubleshoot the noise I'm hearing. I'm an old analog guy and digital control circuits are new to me. I'll wait until I can locate another logic board to try as a replacement. If you or anyone else on the forum has a logic board they want to sell then please let me know.
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I am still puzzled as to why your shorted diodes don't blow the fuse. Wonder if the common core inductor just before the diodes has been blown open?
Good news on your Play5, never tried to fix one. I have a Play3 that shuts down after a few minutes. That I will save for another day.
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Gruv2ths thanks. I get the same so transformer should be fine then. Need to peel back the onion a bit more. Parts have arrived so will start replacing the diodes and capacitors. Also managed to fix one of the Play5 (1st) gen which I bought recently. Just had to replacw the 10 Ohm resistor in the power supply on the primary side.
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Pietje, here is what I measured.
Let me know if it’s confusing
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Pietje Puk - Let me make some measurements on a 36V converter transformer that have here. The continuity should be the same on mine as yours, different turns ratio though I think? (given the lower mains voltage here). If it's the transformer, all is not lost. With the bias converter transformer, when they go open usually once removed you can see where the winding burnt off the termination pin. Fingers crossed that if your transformer has blown open that it can be repaired the same way.

Piperdog - Thanks for the youtube, that helps. Very weird! Wondering if you had a power surge, if maybe some of that over voltage made it through the bias power converter and up to your logic card. If you have a microscope, can you look for cracked ceramic capacitors? I suspect noise that should have been damped is getting in and causing that weirdness.
Pietje, he is using a known good power board so hopefully the Class D stuff is ok.
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Piperdog,

Have you ruled out a problem with the low pass filter (LPF) of the class D amplifier? The noise you hear may be "switching" noise leaking through the LPF...the electrolytic capacitors may need replacing.
Hi Gruv2ths,

I tried both your riser card and mine with no change in the noise level issue. The noise exists whether the analog inputs are used or the source is digital streaming. I posted a video in YouTube. Hopefully you can access it at:

https://www.youtube.com/watch?v=l2rIuxriv_s

I'd like to get my hands on another logic board (i.e. the top board) to see if that would eliminate the noise.
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Gruv2ths, sorry one more question. Do you have the winding diagram for the transformer PQ3230 in the 36V section? I think mine is dead (would explain the broken Schottky diodes). On the primary side I only find one good winding whereas there are 3 pins with wires attached. On the secondary side no connectivity between the thick wires which run into the pcb. Will be tough to find a replacement...maybe need to take it apart and wind a new transformer myself. Thanks!
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Gruv2ths, I measured the 1000uF and have ordered SLPX102M200C4P3 CORNELL DUBILIER - diameter 25mm, height 45mm. Not really high quality but you are right, space is tight on the pcb.
By the way I'm in the city Leiden in the Netherlands. Also have 2x broken Play-5's lying here (1x PSU ticking and 1x amp stages blown up) . Ever done some work on those?
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OK cool, the bulb is worth the work to get running, will be helpful for anything off line you test.
I have had a hell of a time getting those 1000uf caps in the right case sive. A little wider and they are too wide, same goes for the height.
Looking forward to hearing how the parts change works out.
If you don't mind me asking, where are you? I am in Texas.
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First thing I checked was the fuse but that's still fine. Out here we have 230VAC 🆒
Need to check for a bulb, these things are getting hard to find with LED taking over and thr old bulbs no longer on sale.
So far I see no shorts. I just ordered all the parts, including 2x 1000uF. They seem a bit swollen too. I will report back once I have replaced the parts. That will be 2019 for sure 🙂
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I think that is the vbias cap to the integrated pwm chip. Not common but happens.
2 different circuits from the diodes you showed earlier. Another layer of the onion..
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Hey man, no problem, I just happen to be at my computer. I think those are opposite the 36V supply FETs.
I think those are protection diodes for the FETs, but not too sure. I would think since they are primary side and shorted that you would be blowing fuses?
This is not so common in my experience that they are indicative of another problem. This is probably the first layer of your onion. LOL
Are you using a dim bulb in series with your 110Vac? You should be if you are not.
Remove the shorted parts and see happens. Do you have a short between the 36V test point and the RTN36 test point?
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Checked a bit more....smell wasn't semiconductor but electrolyte. The 33uF 400V capacitor died (C16102). See photo....I think I will just replace all of them. Clearly some ageing of parts.
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Gruv2ths, thanks for the quick reply. See picture attached. I have lifted one side for both diodes and 36V rail has no shorts.
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I don't have a unit open in front of me. Can you take a pic of your unit and circle the parts in question.
I know them better visually then by ref-des.

They sound like the 36V supply rectifiers. Could be them or you have a short on the 36V rail. I have seen both problems.
Remove the diodes and see if the parts are shorted.
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Hi folks, I've got a ZP120 with blown power supply too. When powered up I smell "semiconductors". I've been testing an found both Schottky diodes (D16002 and D16006 text: VC3 type: VS-30BQ015PbF) are broken (virtually shortened 0.06V anode-kathode on the diode tester and 0.46V in reverse direction). It seems these are between VPRI and the drain of the Mosfets on the back. Of course I can replace both but just wonder if this is a sign of the main problem. A bit suspect both have blown. The mosfets seem to be okay and also the other pair of diodes in the same circuit (U3J - MURS360T3G; ultrafast rectifiers). Any suggestions?
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Re my ZP100...

The problem it had was that it was not getting any output on the left channel, and within the app it was detecting a fault. This fault caused it to reset the volume to low levels. This made it unusable as an AMP and also not particularly useful to use the RCA outputs. (I'm not sure -- maybe I could have set those to fixed output -- not sure).

In any event, I opened it up today and couldn't see anything wrong with it. However, during my poking around inside, I must have bridged something... I think It was from the AC to DC board to the chassis as I tried to measure the DC voltages there. There were fireworks and popping. I quickly unplugged it.

The interesting thing (to me) is that it is actually more usable now than before! I took the whole thing apart looking for blown capacitors or anything similar. The only thing I found was the both STA505 chips were quite obviously blown... they both literally had pins missing/blown off (see the image). I figured it was very dead and reassembled it to prove it. Lo and behold... It booted up the first time. Not only that, but it stopped throwing faults! There was no audio on either speaker (not surprising given the amp chips were dead). BUT... both RCA outputs were working. SO despite my boneheaded mistake, I now have a device that can at least be used as a sonos connect (no AMP).

I'll probably try to replace the AMP chips. I have two STA508s. These are the chips that are used in the ZP120, but they are pin for pin compatible with the STA505s that are used in the ZP100. I imagine that even if I am successful in replacing the AMP chips (no small task), there is a high probability that there are now other problems on that board, given the fireworks. On the other hand, the blown pins on the amps look to be only the positive and negative supply pins (4,5,6,7,12,13,14,15). If the board traces survived, maybe all the damage is isolated to the amp chips.
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Also, are you using the aux/analog input or a streaming source?
If this is a analog source, it could be your source or the RCA cables. Likely grounding between the two.
When you push play from your controller, you are enabling the 36V supply which powers up the amplifier section.
That supply dies after a while once you push stop. Sounds like the noise is following the 36V supply on and off.

Let me know what you find once you're back. Happy New Year!
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The noise sounds to be a constant level. it's a crackling sound. The volume of the amp works fine - low to high volume. At modest to high volumes the noise is masked of course. My system is update to date re s/w. I'll try reseating the riser card as well as using mine. I can also send you a video with a recording. However, I'm going out of town until after New Year's so I likely won't be able to post anything further until mid next week. Thanks for the suggestions. I'll pursue next week.

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