Altec MX6021

[zerbino]

Re: Altec MX6021

As i understand U1 is NCP1351D https://cdn.badcaps-static.com/pdfs/...f4ba3fa041.pdf may be version D (Latch not connected on board)

[naveenbedre]

Re: Altec MX6021

What is U1 specification number part number

[Behemot]

Re: Altec MX6021

Be sure it is discharged first. Altough a meter will indeed show charged cap as shorted, a one without input protection will most likely do that as the last thing ever

[CapLeaker]

Re: Altec MX6021

see if there is a short at the main filter cap

[zerbino]

Re: Altec MX6021

as i told at 20 post it give light permanently. Unfortunately my knowledge is not enough except to replace U1.

[CapLeaker]

Re: Altec MX6021

Yeah, the old 100W glowing wire type A19 light bulb. Wire it up like in the picture on the phase wire.

[zerbino]

Re: Altec MX6021

Series) Lamp with nichrome coil)
Thanks, i will try)

[CapLeaker]

Re: Altec MX6021

The light bulb trick only works with the old incandecent tye light bulb. It doesn't work with CCFL's or LED type bulbs. The lamp is connected in series on the phase. If the bulb is hooked up in parallel like normal, it will not work as intended either. In order to determent if there still is a short on the primary side of the PSU, did you actually test the output on the secondary to see if there is any voltage coming out?
That little IC is the PWM that connects to the gate drive circuit to the FET. IF the FET was shorted to the gate, then you would have to inspect he gate drive circuit closely and probably replace the PWM. All you can do here is to check all components of the gate drive circuit, check the FET itself, do the lamp test, if there is still a problem, replace the PWM. I use a oscilloscope and a isolation transformer to see if the FET is switching or not. You can check with a DMM if the PWM is getting any power. The PWM also has protection built in, so you'd have to download the spec sheet and measure voltages etc.

[zerbino]

Re: Altec MX6021

Hello all!
Recently i get transistor to change broken SPP08N80C3. As i understand transistor not original, but tested with transistor tester and soldered on pcb. Remember your advice to me i connected 100W lamp and googled how it works). As i understand, lamp must blink and shut down after power on BUT it always glows, so as i understand bord is short short-circuited. Only one ship U1 (1351D PCOI connected 1,3,4,5,7,8) not tested yet and i dont understand how can i test it. Tested only that pins do not call each other and 4 pin is GROUND. And test tested resistors (2W? 15mm length), its 157, 158, 1770, 1781 Ohms

[Th3_uN1Qu3]

Re: Altec MX6021

If the transistor is shorted there is a big chance that the controller chip is also dead. Just something to keep in mind.

[zerbino]

Re: Altec MX6021

Thank You very much for answer. when i'll get transistor, i 'll you lamp for insurance. If it will failed again, i'll let forum know. If I'll fix it, i will let know too.

[momaka]

Re: Altec MX6021

Can You give any additional information about?

Hi zerbino,
the first thing you should do is the incandescent light bulb trick, like this:
https://www.badcaps.net/forum/showpo...4&postcount=70

This will prevent your new parts from blowing up again when you have to test the power supply.

Start by testing all parts on the primary with your multimeter. Any diodes or transistors that show low resistance (less than 300 Ohms) between any of their pins should be removed and checked out of circuit. Resistors should read same as labeled value or lower in circuit (higher resistance that what is printed on them is not good if above their tolerance).

Last but not least, post pictures of your power supply board, even if it looks fairly identical to what ant3202 posted here. After all, there may be small difference in your power supply from his, so it helps for us to see what you are seeing to help you better.

[zerbino]

Re: Altec MX6021

Hello, ant3202. Did you fix your breakage?
I have the same problem. Even made new post on avsforum, but there is now answers.
Here is copy/paste.

I really need help with repairing my Altec Lansing MX6021. It has broken power supply. I have only basic knowledge of physics, a ability to solder, fan, a multimeter and the ability to buy components. After disassembling, I saw that the resistors were burnt (I managed to examine their 1R0 nominal), the capacitor that lost capacitance (a new 68uF 686 16x32mm 450V one was ordered), the punched out fuse T1.6A 1.6A 250V 382 (bought), and it looks like nothing more.
Yesterday I replaced all this and decided to connect without assembling. There was a BIG BADABUM! Resistors burned out again, the fuse too. The capacitor seems to be ok. It's good that I have spare parts and I can change them again. BUT. I'm a bad circuit engineer. But as I heard, maybe someone else has not been able to give proper power. I suggested that this is a power transistor. I tested it with a transistor tester . He showed resistance between the base 5 and 1 ohm. Apparently it's broken. Yesterday I ordered it. Now I'm afraid that I did not miss something else. But I do not know what and how to test. I searched the information on the Internet, but found nothing. No scheme, nothing. Only today I accidentally saw this topic and the person with the same problem as me https://www.badcaps.net/forum/showthread.php?t=60238 But the topic there is not closed. It seems that the person decided it. Could you express your opinion on what else and how to check? Or after the replacement of the transistor SPA08N80C3 (near R15) everything should be fine?
I really do not want to throw this stereo system out. This is a great system! You will not believe it, but I am satisfied with it just like the Elac FS 249.
Sorry for my bad English. I used google translate and my basic knowledge of English.
Best Regards.

Can You give any additional information about?

[ant3202]

Re: Altec MX6021

You can rewire old lamp or just reconnect the socket to a power cord so it is in series with the device.

Alright, I will try.

I guess we are going to have a problem identifying / replacing U1. Maybe have to gamble on it still being good. I guess fuse F1 is blown too? also check those 3 pink resistors inside the heat shrink tubing.

Yep, the F1 has been blown out.



those resistors, four big ones..... i gotta take apart to check.

[CapLeaker]

Re: Altec MX6021

I guess we are going to have a problem identifying / replacing U1. Maybe have to gamble on it still being good. I guess fuse F1 is blown too? also check those 3 pink resistors inside the heat shrink tubing.

[Behemot]

Re: Altec MX6021

thanks for the tips....... light bulb trick is good.....pardon me as im still learning, directly replace the fuse with a light bulb to test in this case?

You can rewire old lamp or just reconnect the socket to a power cord so it is in series with the device.

[ant3202]

Re: Altec MX6021



Some Component lists....

[ant3202]

Re: Altec MX6021

You tell me, just got this BIG sub from Cambridge-whatever-something under Creative, expensive like hell, also SMPS in there (no wonder with the power the thing puts out) and ofc all caps busted. And vitually TONS of that chloroprene stuff EVERYWHERE.

This is just crazy! Power supplies went ahead and even the El Cheapos start using two-forward topologies at least. But in audio equipment, everybody continues to produce the same shit they used to. Often even worse.

When you start testing it, I suggest the lightbulb in series. Often it takes one bad SMD components to make the PWM driver explode again. This hould limit the current and protect it, plus you see right away there's a problem.

thanks for the tips....... light bulb trick is good.....pardon me as im still learning, directly replace the fuse with a light bulb to test in this case?

[ant3202]

Re: Altec MX6021

Those 4 resistors should all have the same value 1R0. Could you post a straight shot, high resolution pictures of the whole front and back side of the PSU? Right now, I'd say there are at least some resistors, the mosfet and the PWM blown. Once hi voltage gets shorted to the gate of the Mosfet, anything in between the Mosfet, including the PWM has to be checked. Only because there is resistance on a resistor, it doesn't mean the resistor is good. You would have to check the value of the resistor and compare it with spec. Usually resistors either burn up (open circuit) or they change their value of resistance HIGHER than spec. If you do up an order, get the PWM too. Probably only cost you an extra 1$ anyway. What is printed on U1?

Hi CapLeaker

U1 is behind... i suspect it is blown too.
cannot see any wording on it like

Using a magnifying glass....
First Row: 03 510
Second Row: PA TM

[CapLeaker]

Re: Altec MX6021

Those 4 resistors should all have the same value 1R0. Could you post a straight shot, high resolution pictures of the whole front and back side of the PSU? Right now, I'd say there are at least some resistors, the mosfet and the PWM blown. Once hi voltage gets shorted to the gate of the Mosfet, anything in between the Mosfet, including the PWM has to be checked. Only because there is resistance on a resistor, it doesn't mean the resistor is good. You would have to check the value of the resistor and compare it with spec. Usually resistors either burn up (open circuit) or they change their value of resistance HIGHER than spec. If you do up an order, get the PWM too. Probably only cost you an extra 1$ anyway. What is printed on U1?