Hi Steve,
Swapping out mosfets blindly like that seems like an excercise in futility.
Emitter followers aren't totem poles as I understand them, but without giving the circuit away (since it's not our place to do so) as Bruno has stated multiple times in the past the drivers of the 400 are slew controlled, which accounts for the lesser variance in timing/thd you were seeing.
Regards,
Chris
Swapping out mosfets blindly like that seems like an excercise in futility.
Emitter followers aren't totem poles as I understand them, but without giving the circuit away (since it's not our place to do so) as Bruno has stated multiple times in the past the drivers of the 400 are slew controlled, which accounts for the lesser variance in timing/thd you were seeing.
Regards,
Chris
Hey all,
One of my UCD180AD modules has sufferred a similar fate. R29 was a bit charred, and R39 was split in half. I'll go check everything out when I get home after reading this thread, but these were the only obvious things I noticed before I left for work.
Now, can anyone give me the specific model numbers to replace these, R29 seems fairly easyto get, but R39 I must be looking in the wrong places 🙁
Any help would be greatly appreciated.
Cheers,
Nathan
One of my UCD180AD modules has sufferred a similar fate. R29 was a bit charred, and R39 was split in half. I'll go check everything out when I get home after reading this thread, but these were the only obvious things I noticed before I left for work.
Now, can anyone give me the specific model numbers to replace these, R29 seems fairly easyto get, but R39 I must be looking in the wrong places 🙁
Any help would be greatly appreciated.
Cheers,
Nathan
Would this be a suitable replacement for R39?
http://au.farnell.com/jsp/endecaSearch/partDetail.jsp?sku=3610380
And R29?
http://au.farnell.com/jsp/endecaSearch/partDetail.jsp?sku=109312
Cheers,
Nathan
http://au.farnell.com/jsp/endecaSearch/partDetail.jsp?sku=3610380
And R29?
http://au.farnell.com/jsp/endecaSearch/partDetail.jsp?sku=109312
Cheers,
Nathan
Hi Nathan.
Both of those resistors you linked to should work fine. All you need to worry about is getting a 1kohm 0805 resistor for R29 and a 0.05ohm 1W 2512 resistor for R39.
If you want almost exact (they look very similar too) replacements, try searching for these part numbers on Digi-Key:
WSLG-.05CT-ND for R39 and RHM1.00KCCT-ND for R29.
A word of caution - if you fried R39 then you really had a lot of current going through the output FETs. If my FETs were fried and R39 was fine on my modules then I have no doubt that both of your FETs are fried as well.
Both of those resistors you linked to should work fine. All you need to worry about is getting a 1kohm 0805 resistor for R29 and a 0.05ohm 1W 2512 resistor for R39.
If you want almost exact (they look very similar too) replacements, try searching for these part numbers on Digi-Key:
WSLG-.05CT-ND for R39 and RHM1.00KCCT-ND for R29.
A word of caution - if you fried R39 then you really had a lot of current going through the output FETs. If my FETs were fried and R39 was fine on my modules then I have no doubt that both of your FETs are fried as well.
This is where I ask a really n00b question and ask what the FET's look like 😛
I'm going to assume they're the two things attached to the sink?
I'm going to assume they're the two things attached to the sink?
Well, if i'm checking the right thing 😉, one of them has gone short circuit throughout the chip.
Good times, so theres those to replace, as well as the resistors. Anything else in that bit that is likely to have died?
Good times, so theres those to replace, as well as the resistors. Anything else in that bit that is likely to have died?
I'm not quite sure, one can only imagine the case has touched the PCB at some stage as it wasn't fixed on properly. My dog has a habit of running into the speaker wiring (and yep, it's out of the way).
My girlfriend was just watching a DVD then they said they heard a pop and a spark. She neglected to mention this until I wondered why I had no right channel. Sheesh!
My girlfriend was just watching a DVD then they said they heard a pop and a spark. She neglected to mention this until I wondered why I had no right channel. Sheesh!
Brian,
Cheers for the heads up on those components!
After some help from classd4sure, Ive established the best course of action is to repair the resistors that were destroyed, and replace the FET's. Everything else *touch wood* that we tested appears to have survived.
The positive rail was the one that bit it, is there anything in particular apart from these and the driver transistors I should check?
I'm looking to get 4 STP14NF12FP to go on the modules, where can I get these from? I'm having a bit of difficulty locating them.
Cheers,
Nathan
Cheers for the heads up on those components!
After some help from classd4sure, Ive established the best course of action is to repair the resistors that were destroyed, and replace the FET's. Everything else *touch wood* that we tested appears to have survived.
The positive rail was the one that bit it, is there anything in particular apart from these and the driver transistors I should check?
I'm looking to get 4 STP14NF12FP to go on the modules, where can I get these from? I'm having a bit of difficulty locating them.
Cheers,
Nathan
No problem Nathan.
Good luck finding those FETs - I looked everywhere for them as well. Fortunately, Hypex was kind enough to send me some replacements! They sent me 4 and I'd be glad to send 2 your way if you'd like.
Good luck finding those FETs - I looked everywhere for them as well. Fortunately, Hypex was kind enough to send me some replacements! They sent me 4 and I'd be glad to send 2 your way if you'd like.
You didn't replace the other ones on your other modules so they matched? Or did you only have one module?
I only have one module. I had planned on using it as a sub amp, but only got to listen to it for a few minutes...
Ahh, no wuckas. If I can't find a source for them, i'll give you a holler, thanks heaps! It's just I have a pair of them and really want to keep them matched.
Did you get it back to working in the end?
Did you get it back to working in the end?
You don't really need to worry about matching the FETs. They're being used as switches so what's the point? Maybe if you were matching the Vgs threshold voltage or on state resistance... but even then I don't think minor variations (the kind you see if you just sample two devices from the same manufacturer) will make any audible difference.
Sadly, I haven't had time to fully probe around my module to make sure all the driver components are ok. It's even harder to know for sure without a schematic. I had planned to trace it out one of these days but haven't had the time. I'd hate to replace the FETs and have them blow again because of a bad component in the driver circuit.
Sadly, I haven't had time to fully probe around my module to make sure all the driver components are ok. It's even harder to know for sure without a schematic. I had planned to trace it out one of these days but haven't had the time. I'd hate to replace the FETs and have them blow again because of a bad component in the driver circuit.
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