ICE3B0365J Troubleshooting (W200 Sub)

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Not looked at it for a few days so in the same situation as my last post. I need to find what isn't happy as it is obviously something intermittent. Going to reflow a few joints and double check the tracer repairs I had to do. I have freeze spray and an ESR meter now so more options if needed.
Is it definitely bad caps on your board then?

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Okay, I have got it working a few times now and it initially seems fine, can turn it on and off, play with switches etc. but after it is on about 15 mins once it gets hot it doesn't like it and then turning it back on results in flashing red light. Let it cool down and fine again so it definitely seems like a temperature issue and the 51ohm resistor and the mosfet heatsink get very hot.

[R_J]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Do have the original resistor that was damaged? are you sure it was 51Ω and what type of resistor did you replace it with, it should not be a wire wound resistor. If it was just the outer coating that was crumbling the actual resistor was likely still good.
Looking at the part number on the resistor it IS a wire wound resistor so you now have a coil in series with a capacitor across the transformer

[CapLeaker]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Measure the voltage on both sides of the resistor until the unit clunks out.

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Ahh, that might be it. The pictures sent over (attached) looked like a wire wound so that is what I told him to get. It supposed to be a metal oxide then?
Would that cause the behaviour I'm getting then?

I was thinking about getting a higher wattage one anyway with the amount of heat and the fact the old one had crumbled, so a 51ohm 7W metal oxide?
Much appreciated

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Actually, am I right in thinking that is a 7W wire wound? And there is a 5W in it...urgh

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Measure the voltage on both sides of the resistor until the unit clunks out.

Will do. I think it is looking quite possible it is the cause especially if the wrong part is in there - I know it gets very hot anyway due to pictures of other boards.

[R_J]

Re: ICE3B0365J Troubleshooting (W200 Sub)

W7J does seem to point to a wire wound 7 watt 5% resistor, It just seems a bit odd to place a wire wound resistor in that part of the circuit but if that is what was there before it is likely ok.
That resistor and the capacitor in series is the snubber circuit

[CapLeaker]

Re: ICE3B0365J Troubleshooting (W200 Sub)

I’d say the original resistor was a 7w 51ohm resistor, just like rj identified. I just wonder why this amp is cutting out now. First I thought maybe the resistor is changing value during operation, but now I am not sure if the amp actually isn’t in over heat shutdown or something like that.

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

So having a 5W in there is not going to be doing it any favours is it?
Will order a 7W and see if that helps. Kinda wish I had infrared goggles so could see if the heat is just focused around there. Not really used freezer spray before so don't feel spraying it on a live 330V circuit is the best idea.

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

This will sound like a noob question but I have a bunch of these 5W resistors - before ordering a bigger one could I run 2 in series in parallel with 2 others in series for 51ohm 20W just to test that this is the issue?

[Per Hansson]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Yea you could but it's not going to be the issue: a 5W and 7W resistor is the same.
One is just physically bigger and by that able to dissipate a bit more heat via convection.
A smaller resistor can easily handle a higher than rated load as long as you cool it with forced air cooling.

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Oh yeah, but seeing as heat seems to be what is causing the issue and with a 7W being the original component and having a 5W in now I am just wondering how much of an effect the extra heat dissipation will have. Grasping at straws really.

[R_J]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Okay, I have got it working a few times now and it initially seems fine, can turn it on and off, play with switches etc. but after it is on about 15 mins once it gets hot it doesn't like it and then turning it back on results in flashing red light. Let it cool down and fine again so it definitely seems like a temperature issue and the 51ohm resistor and the mosfet heatsink get very hot.

What happens to the voltages when this flashing happens? Do the standby voltages drop or does the main 54 volts to the amp board drop?
That 5 watt snubber resistor is not really going to effect the amp operation, it will get hot but so will a 7 watt
One component to check in the standby circuit is D2, sometimes it can short, it is across the 2.2Ω R20 so one end of the diode needs to be removed to check it.
It is also possible your problem is on the Amp board?

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

One of the 10kOhm resistors near that 5W had corrosion on a leg but tested okay - just took it out to check and the leg snapped so need to order a replacement for that before I can do anything else now.

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Will follow up on this once I have replaced that resistor, hopefully tomorrow.

Before I got it working the whole of the secondary side was dead, and no idea what I did to get it working - I had just removed, tested, and resoldered a few parts. That D2 tested fine as did every other component in that area including the transformer, actually running out of things to test on that side of the board so was planning to just go systematically through the remaining parts just to rule them out. The fact the corroded leg of that resistor (R38) crumbled so easily makes me suspicious as it does get hot too.
Once replaced I will set up a couple of multimeters and monitor both sets of voltages though, see what happens, and report back.

I'll say it again, thanks everyone for your input with this, it is very much appreciated.

What happens to the voltages when this flashing happens? Do the standby voltages drop or does the main 54 volts to the amp board drop?
That 5 watt snubber resistor is not really going to effect the amp operation, it will get hot but so will a 7 watt
One component to check in the standby circuit is D2, sometimes it can short, it is across the 2.2Ω R20 so one end of the diode needs to be removed to check it.
It is also possible your problem is on the Amp board?

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Right, resistor replaced but now I can't get it working at all, just blinking red light. I replaced a carbon resistor with metal, will that make a difference? Voltages on the startup and around the IC are jumping all over the place again. Whether I have the second board connected or not the only stable voltage on the board is the main DC up to the starter transformer.

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Scratch that, I left it alone for an hour and it suddenly started working again...the behavior of this board has me baffled.
Just left it with the volume up full (low input so as to not annoy the neighbours), after a few minutes it cut out went to flashing and then kicked back in again after a few seconds...going to leave it running and monitor it.

[CapLeaker]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Something is intermittent somewhere. Weird. Try either heating or freezing certain components and applying some pressure?

[SFB]

Re: ICE3B0365J Troubleshooting (W200 Sub)

Yeah, that is obviously why it has been so difficult to diagnose. I tried monitoring readings but once it goes all voltages on the board are effected so it's impossible to narrow it down. I left it on for an hour after the last post and it was fine. Off/on and red light flashing again but in a weird random morse-code like pattern which was new, flicked a few switches and came back on again. On/off again a bunch of times and was fine every time, so left it on for another half hour and occasionally it cut out and flashed red briefly but on for the most part.
I will definitely try that again - I did poke around a bit when you last mentioned it but then it was just flashing constantly so at least now I can see if I can make it die by poking and heating/cooling. Bit worried about the moisture left by freeze spray on a live board though. Never used it before and don't want to fry anything...though at least it would be obvious what was wrong then haha

Something is intermittent somewhere. Weird. Try either heating or freezing certain components and applying some pressure?