SSLV1.1 builds & fairytales - Page 160

Salas · 6th July 2012, 10:28 PM

That is 126C. Too hot especially for the semi. Are you using a contact thermocouple to read the temp?

mjock3 · 6th July 2012, 10:29 PM

No infared.

Salas · 6th July 2012, 10:32 PM

In what room temp, CCS setting, load dummy? Are you aiming the black part of the semi's case from about 15cm (half foot) distance?

mjock3 · 6th July 2012, 10:36 PM

Room temp. is about 80. I have just shy of 1 amp that I am shooting for. I grabbed a thermocouple and am checking with that now. It is showing 188 F.

mjock3 · 6th July 2012, 10:41 PM

Thermo is now showing about 200 F. I use it for roating coffee so I am not sure it is accurate in this situation as it is .188 in diameter. Infared is still showing about 260-270 F.

mjock3 · 6th July 2012, 10:44 PM

Yes it is about a half a foot. It was doing it with dummy load. Which was 5R5. I have since hooked it up. I have now unplugged it seeing as how you say that is too hot.

Salas · 6th July 2012, 10:46 PM

Best case 188F=87C. Junction to case is 1.7C/W in that semi (IR datasheet), so you are at 100C junction temp for say 5W. (Meltdown @ usually around 175C). Either you got a very small sink for that setting, or you are using a dummy load that isn't simulating as strong current draw as the destination load's average and too much is burned on the Mosfet. Your voltage setting and dummy load value please? Also some info about your sink (C/W) or photo?

mjock3 · 6th July 2012, 10:57 PM

Voltage setting is 5 volts.

Not sure how to upload picture. When I had a dummy load hooked up it was 5r5 15 watt

Salas · 6th July 2012, 11:04 PM

Go Advanced under reply messages, there is upload pics menu. Make it say 1024X768 first.
Something here does not compute. If you got 1A CCS setting and a 5.5R dummy, then 0.9A should have gone to the dummy @ 5V. The output Mosfet should dissipate only 0.1A*5V=0.5W. But yours is suspiciously hot. Maybe you run much higher CCS? You will know by voltage across the CCS setting resistor divided by its value. Is the dummy hot at all?

mjock3 · 6th July 2012, 11:04 PM

Heat sinks I am using are Aavid Thermalloy 8C/W P/N 531302B02500G

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6th July 2012, 10:28 PM	#1591
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	That is 126C. Too hot especially for the semi. Are you using a contact thermocouple to read the temp?

6th July 2012, 10:29 PM	#1592
mjock3 diyAudio Member Join Date: Jan 2011 Location: Wisconsin	No infared.

6th July 2012, 10:32 PM	#1593
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	In what room temp, CCS setting, load dummy? Are you aiming the black part of the semi's case from about 15cm (half foot) distance?

6th July 2012, 10:36 PM	#1594
mjock3 diyAudio Member Join Date: Jan 2011 Location: Wisconsin	Room temp. is about 80. I have just shy of 1 amp that I am shooting for. I grabbed a thermocouple and am checking with that now. It is showing 188 F.

6th July 2012, 10:41 PM	#1595
mjock3 diyAudio Member Join Date: Jan 2011 Location: Wisconsin	Thermo is now showing about 200 F. I use it for roating coffee so I am not sure it is accurate in this situation as it is .188 in diameter. Infared is still showing about 260-270 F.

6th July 2012, 10:44 PM	#1596
mjock3 diyAudio Member Join Date: Jan 2011 Location: Wisconsin	Yes it is about a half a foot. It was doing it with dummy load. Which was 5R5. I have since hooked it up. I have now unplugged it seeing as how you say that is too hot.

6th July 2012, 10:46 PM	#1597
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Best case 188F=87C. Junction to case is 1.7C/W in that semi (IR datasheet), so you are at 100C junction temp for say 5W. (Meltdown @ usually around 175C). Either you got a very small sink for that setting, or you are using a dummy load that isn't simulating as strong current draw as the destination load's average and too much is burned on the Mosfet. Your voltage setting and dummy load value please? Also some info about your sink (C/W) or photo?

6th July 2012, 10:57 PM	#1598
mjock3 diyAudio Member Join Date: Jan 2011 Location: Wisconsin	Voltage setting is 5 volts. Not sure how to upload picture. When I had a dummy load hooked up it was 5r5 15 watt

6th July 2012, 11:04 PM	#1599
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Go Advanced under reply messages, there is upload pics menu. Make it say 1024X768 first. Something here does not compute. If you got 1A CCS setting and a 5.5R dummy, then 0.9A should have gone to the dummy @ 5V. The output Mosfet should dissipate only 0.1A*5V=0.5W. But yours is suspiciously hot. Maybe you run much higher CCS? You will know by voltage across the CCS setting resistor divided by its value. Is the dummy hot at all?

6th July 2012, 11:04 PM	#1600
mjock3 diyAudio Member Join Date: Jan 2011 Location: Wisconsin	Heat sinks I am using are Aavid Thermalloy 8C/W P/N 531302B02500G