Hi guys
I've been getting more air con controller boards of various brands for repair - mainly the ones from the outdoor compressor unit and I realise I have a lot of gaps in my specific knowledge, while being pretty good at electronic repair in general.
Does anyone know of any good resources for information on this sort of repair? I'm hoping here there will be some guys who are experienced in this. I'd specifically like more info on how the controller PCB works, because I expect they are all pretty much the same, and especially how it communicates with the indoor unit (protocols,...
dicky96
Sun Seeker
Last Activity: 04-02-2025, 07:57 AM
Joined: 03-28-2017
Location: Sunny Gran Canaria
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Air Con PCB repair : some general question
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JBL EON 515XT No treble
Hi guys I'm trying to fix this powered speaker
I have bass but no treble. The horn speaker works OK but I have no audio signal going into or out of the TDA7293 amplifier chip that drives the horn. The chip has power +/- 24V
I don't appear to have any HF signal coming from the preamp/mixer board, only LF. The signal present LED is on/flashing.
I have a schematic which seems to be the correct one for the main amp but not for the mixer - see attached
For example on my mixer PCB, I don't have SW5 which is referred to on the schematic. Also I don't...Last edited by dicky96; 04-28-2023, 07:26 AM. -
MSI Z270-A Pro (MS-7A71 Ver 1.2) Schematic Request
Hi guys
Does anyone have a schematic or board view for MS-7A71?
Thanks
Rich -
Bang & Olufsen (HP) Omen Laptop power light flashes once but no boot
Hi guys
I have a B&O Omen laptop here. It has very specific fault symptoms, hopefully someone can give me some guidance
If I plug in a known good 180W third party charger the little LED next to the power jack on the laptop flashes red once, but the laptop will not start. It will not flash red again unless you unplug and reconnect the power.
If I remove the main battery (I can't see a cmos battery) then the led by the jack does not flash when I plug in the adapter, but if I press the power on button with adapter attached it flashes once white every time... -
Re: How to desolder power devices on PCB covered with silccone adhesive?
Thanks for all the suggestions. I managed to work on this by removing the two large capacitors and the two large chokes between the heatsinks. I could then unbolt the transistors, put a piece of cord through the hole on the transistor, heat the three pins at the same time and pull them like teeth
Rich -
How to desolder power devices on PCB covered with silccone adhesive?
Hi guys
I'm working on some whatspower P222C power supplies. I have short circuits in either or both of the PFC mosfets and/or output transistors. I need to remove at least one heatsink to diagnose this but they are very hard to get to (the device screws) and there is this white sh!t everywhere on the PCB (which is double sided tracks at least)
Anyone can suggest the best way of working on this sort of thing?
see pics... -
Re: Trying to identify two SOT23 SMD codes, devices from mining PSU
Anybody?Leave a comment:
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Trying to identify two SOT23 SMD codes, devices from mining PSU
Hi guys
Does anyone know what these two components are?
First one is SOT23 marked LPS 6CB
The other one is SOT23-6 marked S43BbbA
TIA
Richard... -
Re: Hitachi V19B01922 Channel Tune problem
Nobody~??Leave a comment:
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Hitachi V19B01922 Channel Tune problem
Hi Guys
I have a customer who has two Hitachi TVs in his bar, one is the model in the thread title and the other is a larger screen but has the same setup menu
He also has an LG TV, so three screens in the bar
I installed three Satlink ST-6503 DVB-T Modulators
This model [url]https://www.aliexpress.com/item/32916553905.html[/url]
These connect to three satellite receivers via HDMI cables and then connect to a 4 way RF Amp that connects to the TVs on aerial cable. There is no incoming terrestrial antenna. I set the channel ID on the modulators... -
Re: Trying to find datasheet for 3108L
Thanks
It's about 24C here daytime, mostly sunny, and 16C night time. This is part of Europe, we are in the EU single market (but not the customs union)Leave a comment:
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Trying to find datasheet for 3108L
Hi guys
This chip is in a 65W USB-C PSU. It doesn't drive the Transformer directly, though it clearly has a high voltage pin as there is the typical missing pin space next to it. There is a mosfet connecting to the SMPS transformer primary.
I think Vcc may be on pin 5 but don't take that as gospel.
Can anyone identify it? I'm looking for a datasheet
Thanks
Rich... -
Re: Does anyone have a schematic for Samson TXM16 Powered Mixer?
That looks like it could well be the correct one, thank youLeave a comment:
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Does anyone have a schematic for Samson TXM16 Powered Mixer?
Hi guys
Does anyone have a schematic for this? The fault is both protect lights on. I fixed one problem already that was causing the negative rail to both amplifier channels to go to -90V with +45V on the positive rail (It's a class G design)
I now have 45V on both rails +/- but one of the amplifier channels has about 20V DC on all the emitter resistors and it all reads weird because the base of the NPN output transistors is about 8V so they are reverse biased, yet the base of the PNP output transistors reads about 19.3V, so 0.7V less than the emitters so those appear be forward...Last edited by dicky96; 11-21-2022, 11:46 AM. -
Re: Please Help Identify this SOT23-6 DC DC converter smd code 200
Thanks guysLeave a comment:
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Please Help Identify this SOT23-6 DC DC converter smd code 200
Hi guys
Does anyone know what this component is (see pic)
marking 200
package SOT23-6
it is some sort of DC DC converter, it is from a MAG322 STB, the input is directly from the 12V power jack
Pin 1 --> Ground
Pin 2 --> Inductor Coil (Vout)
Pin 3 --> Vin (12V)
It has a low resistance 10 ohms from Vin to ground, failed after the incorrect power supply was plugged in, 5V instead of 12V. In my experience the lower voltage seems to kill the chip by making it draw more current in an attempt to generate the correct... -
Re: lenovo IdeaPad S145 bios needed
Fixed, thank you SMDFlea
Leave a comment:
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Re: 25B127DSIG programming with TL866CS?
A pirate walks into a bar and orders beer. He has a parrot on his shoulder
The parrot says
pieces of eight pieces of eight pieces of eight pieces of nine pieces of eight...
A guy next to him says 'excuse me but did your parrot just say pieces of nine?'
Oh don't worry about that says the pirate, it must have been a parroty error...Leave a comment:
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Re: 25B127DSIG programming with TL866CS?
Hi stj
No mate it is 25B127DSIG (see pic)
It's from a Lenovo S145 laptop
According to the schematic the chip should be W25Q128JVSIQ. This is not on the list of supported IC either so I used W25Q128BV
This seems to have worked
[url]https://www.badcaps.net/forum/showpost.php?p=1153566&postcount=153[/url]
I guess it is compatible.
RichRe: 25B127DSIG programming with TL86... <br /> It's...Leave a comment:
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Re: lenovo IdeaPad S145 bios needed
Hi guys
I have the same problem as many of you - flashing white power LED, black screen and no Vddgt power rail
I have attached my eprom dump. On my PCB the eprom is actually a 25B127DSIG. My TL866 does not support this.
According to the schematic (attached if anyone wants it) the chip should be W25Q128JVSIQ. This is not on the list of supported IC either so I used W25Q128BV and it appears to have read it OK
Can one of you smart guys give me a good data file
My laptop is
...Last edited by SMDFlea; 04-10-2023, 08:44 AM.Leave a comment:
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