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Francesc V. replied to Computer SMPS has voltages from a moment and then disapear

in Troubleshooting Power Supplies and Power Supply Design

Yesterday, 05:20 AM
Finally!!!!, I discovered and fixed the problem.

I was getting a stable 370V in the primary cap, so PFC was working.

Then I started measuring the REF voltage for each of the 431 that are on the PCB. One of them had no voltage in pin1, others 2.5 stable volts.
Then following up neighbors I realized that pin1 was directly connected to a resistor that it should be 820 ohms, but I was getting K ohms............so I've replaced and auto-magically I started getting the expected 3.3V.

Joint between pin 2-3 removed and SMPS switches on normally.
...

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Francesc V. replied to Computer SMPS has voltages from a moment and then disapear

in Troubleshooting Power Supplies and Power Supply Design

04-23-2025, 01:59 PM
Thanks!!! That was the most valuable tip so far :-) I will write it somewhere........shorten FPO to turn on smps whatever it takes :-)

By grounding FPO pin to GND (shorted pins 2-3 in the supervisor) the SMPS turns on.

I had just time to measure secondary voltages before my wife started shouting, however I see secondary STABLE voltages (stable but wrong).

In the 3.3 rail I have a stable but WRONG 9.2 V
5V, -12V and 12V rails are stable and with the RIGHT voltage.

With a secondary stable voltages, I guess there is nothing wrong in...

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Francesc V. replied to Onkyo A8200 - Not the right voltages in some transistors

in Troubleshooting Audio Equipment

04-20-2025, 03:47 AM
Not sure if I am going in the right direction, but my problem is this -41V I am reading in one of the legs of C515, which is base of Q523.

By removing Q515 from the circuit, this -41V turns into milivolts.

Vbe in "removed Q515", measured from R525 and R535 is 1.3V which tells me that transistor is switched on and that's the reason I am having the wrong voltage above.
In addition, Vbe in Q513 is 0.2mV which tells me that that transistor is closed.

So, not sure if both transistors should be on and both voltages will make that in...

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Francesc V. started a topic Onkyo A8200 - Not the right voltages in some transistors

in Troubleshooting Audio Equipment

04-19-2025, 07:17 AM
Onkyo A8200 - Not the right voltages in some transistors

Hi:

I am trying to repair this amplifier that I've bought as faulty. I've found some transistors damaged, the ones where I am drawing a red circle.

With the final transistors not yet installed (the expensive ones), I've started to measure some voltages:

Where I am supposed to have 1.12V (base Q524/Q523) I am reading -42V..................both channels don't seem ok.
Where I am supposed to have -1.12V (base Q526/Q525) I am reading -44V..................both channels don't seem ok.
I removed and tested Q514,Q516 & Q513,Q515 but the analyzer...

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Francesc V. replied to Computer SMPS has voltages from a moment and then disapear

in Troubleshooting Power Supplies and Power Supply Design

04-18-2025, 06:18 AM
FPO pin goes high when powering on the SMPS (4.3V) and remains the same (maybe decreases some milivolts) when pressing PSON to switch on the SMPS.

I put loads in every rail (3.3, 5V, 12V). 40W bulb with a switch.

Momentary voltages when switching on are 4.3, 3 and 11............... so I guess that for some reason there is over-voltage in the 3.3 rail and the supervisor protects the SMPS (I measure 4.3V, then decreasing in pin 5 from GR8313)

Regards,
Francesc....

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Last edited by Francesc V.; 04-18-2025, 06:24 AM.
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Francesc V. replied to Computer SMPS has voltages from a moment and then disapear

in Troubleshooting Power Supplies and Power Supply Design

04-16-2025, 03:23 AM
Sure..........never rely on Chinese Watts :-)

I scanned the PCB, just for reference. On the secondary side, the channel supervisor IC it's a GR8313. On the primary side, the PFC IC chip it's the CM6800.

Vcc (pin13 on CM6800) has no voltage.....only the first moment it seems it has, but then the capacitor gets discharged, I guess.

Regards,
Francesc....

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Last edited by Francesc V.; 04-16-2025, 03:39 AM.
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Francesc V. replied to Computer SMPS has voltages from a moment and then disapear

in Troubleshooting Power Supplies and Power Supply Design

04-16-2025, 12:17 AM
It's model [B]YL ATX-0200.[/B] You can get it in Alibaba :-)

[ATTACH=JSON]{"data-align":"none","data-size":"medium","data-attachmentid":3616177}[/ATTACH]It's model [B]YL ATX-0200.[/B] You can get it in Alibaba :-)

[ATTACH=JSON]{"data-align":"none","data-size":"medium","data-attachmentid":3616177}[/ATTACH]It's model [B]YL ATX-0200.[/B] You can get it in Alibaba :-)

[ATTACH=JSON]{"data-align":"no...

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Francesc V. started a topic Computer SMPS has voltages from a moment and then disapear

in Troubleshooting Power Supplies and Power Supply Design

04-15-2025, 01:54 PM
Computer SMPS has voltages from a moment and then disapear

Hi:

I am trying to repair a 1000W cheap power supply, but so far, with no much success.

The ATX has [B]stable 5V STBY.[/B]
When shortening PsuON to ground, it triggers all voltages for a fraction of a second and then disapear (I see the leds flashing for a moment from the ATX tester)

- I removed and tested the capacitors. They are OK.
- Removed and tested the Output rectifiers from the secondary.
- Removed and tested the Mosfets from the primary.
- Outputs are not shorted.
- Overakk review of the solder joins.
...

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Francesc V. replied to Tele-master AS-20 amplifier. No output sound, just noise

in Troubleshooting Audio Equipment

04-07-2025, 06:20 AM
Hi everyone............I wasn't able to find the schematic for that one.......so sorry. :-(

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Francesc V. replied to Help me to identify this Thermal fuse from my sister's mixer

in General Electronics Technical Discussion

03-22-2025, 01:33 PM
On the mixer, it's written 1000W :-)

It's a Bosch mixer........ Do you have this brand in the USA?

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Francesc V. replied to Help me to identify this Thermal fuse from my sister's mixer

in General Electronics Technical Discussion

03-19-2025, 02:00 PM
It only gets about 50W from the main......I observed high peeks of about 70W. For the time being, it's delivered with a "proper calibrated fuse" 🤣

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Francesc V. replied to Help me to identify this Thermal fuse from my sister's mixer

in General Electronics Technical Discussion

03-19-2025, 12:26 AM
Thank you all for the responses and links.

Mixer is a 1000W bosch mixer.
I confirm that we need to find a substitute for this piece. As long as I solder a very thin cooper wire, it works. :-)

Now that it works, I will measure the load and then we will decide the fuse.........not sure if it's the right approach. xDDD

Regards,
Francesc....

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Last edited by Francesc V.; 03-19-2025, 12:35 AM.
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Francesc V. started a topic Help me to identify this Thermal fuse from my sister's mixer

in General Electronics Technical Discussion

03-18-2025, 05:48 AM
Help me to identify this Thermal fuse from my sister's mixer

Hi everyone:

This is the second time I have my sister's mixer on the bench. First time I identified a blown tiristor......this time I guess it's the thermal fuse (reads open).

My understanding is that it should be (NC) normally closed and open at 85C?????

Could you help me to identify/get a good one? How many amps? I was about to buy a NC 10A, 85 celcius in Aliexpress. (ceramic one)......but I guess is too much.

Wording in the back......... "limitor 16", "T160".

Thanks in advance,
Francesc....

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Last edited by Francesc V.; 03-18-2025, 06:34 AM.
Francesc V. replied to Are these 2 chips both compatible (GR8313) vs (HY510N)??

in General Electronics Technical Discussion

03-06-2025, 08:14 AM
Thanks stj....

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Francesc V. started a topic Are these 2 chips both compatible (GR8313) vs (HY510N)??

in General Electronics Technical Discussion

03-06-2025, 05:57 AM
Are these 2 chips both compatible (GR8313) vs (HY510N)??

Hi:

I have a SMPS that has GR8313 as power supply supervisor chip. I have already ordered these chips, but today doing housekeeping and doing some catalogue of all "shit", I realised that HY510N chip which I already have, has the same pinout and I would say will do the job.

Do you think that I could use HY510N instead of GR8313 for trying to repair the SMPS?

Attaching both data sheets for a fast checking.

Thanks in advance.
Francesc....

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Francesc V. replied to How to simulate a potenciometer encoder?

in General Electronics Technical Discussion

02-02-2025, 12:44 AM
Not very difficult, but I needed a microscope to align correctly the three internal pins that make contact with the encoded wheel.

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Francesc V. replied to How to simulate a potenciometer encoder?

in General Electronics Technical Discussion

02-01-2025, 01:58 AM
Soldered on the PCB, I removed/bent the 4 staples.............then disassembled parts, cleaned with Isopropanol and mount them again.

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Francesc V. replied to How to simulate a potenciometer encoder?

in General Electronics Technical Discussion

01-30-2025, 03:47 AM
Thank you all for the feedback.
I've already ordered one........but in the meantime I managed to open it, clean it.........and it's back to life. Not sure how much will last :-)...

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Francesc V. started a topic How to simulate a potenciometer encoder?

in General Electronics Technical Discussion

01-28-2025, 01:43 PM
How to simulate a potenciometer encoder?

Hi:

I have a Rotel amp where the main volume works badly...........going clockwise the volume goes up and down.......anticlock wise more or less the same..........it's like a fight to turn volume up or down......xDD

Here is the schematic.

My question is how I could simulate to turn volume up or down to isolate the issue......maybe it's not the encoder but it's the main board.

A PWM signal between pin 1 and 4???

Thanks in advance,
Francesc.

[ATTACH=JSON]{"alt":"Click image for larger version...

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Francesc V. started a topic Technics SA-AX530 in protected mode. Overload message

in Troubleshooting Audio Equipment

11-18-2024, 12:39 AM
Technics SA-AX530 in protected mode. Overload message

I got a request from a friend of mine to have a look to his amplifier. When switching on "OVERLOAD" was displaying, however from time to time, message disappears and protection was removed.
I took some time in visual inspection (no bold caps, no solder joins, no burnt components neither hot burnt areas). I took some time to measure transistors and diodes. Everything seemed ok.

I realized that when OVERLOAD was on, pin 13 on IC601 (RSN307M44A-P) measured 5V. From time to time, when Amplifier was not protected pin 13 measured the right -1.5V
(Pin 13 goes through...

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Last edited by Francesc V.; 11-18-2024, 12:46 AM.