Tapco Juice J.1400 slave amp
One fan fails to start. Presumably 12V but only 3.8 to 4V over both fans
at start up. Recognised problem /solution.? Assuming its like the 2500 (sm out there) then 39R/3W dropper, is 27R/2W in here. I can see it being replaced with 10R + PTC thermistor of 15R hot . It would seem that , when operating at power, a TO220 transistor bypasses that resistor, proportionally. |
Tapco Juice J.1400 slave amp
12V .37A fans. Same circuit structure as the J2500. Could not find a
suitable PTC. May as well use the TIP41 and put an R and C between 12V and its base for switch-on full-on confirmation and 47R over the existing 27R 2W, to raise the "cold" fan voltage a bit, 4V I consider too low, 1/2 normal rating is waht I'd expect for slow running, plus initial kicker voltage. Fans are fine, the front one clogged with dust and hair. |
Tapco Juice J.1400 slave amp
The 4V over the fans was due to the dropper going high to 38R, 27R 5W
vitreous went in there instead. 2200uF/25V and 1K between base and 12V now gives the more reliable fans full-on at switch-on then drops down over about 5 seconds to low noise 6V drive, waiting for high power , on demand. |
Tapco Juice J.1400 slave amp
Are you sure it is PTC ? Kinda seems like it ought to be NTC.
|
Tapco Juice J.1400 slave amp
|
Tapco Juice J.1400 slave amp
I originally red that 2W as 27R. Looking closer to it ,
orange/brown/black. Not E24 value but orange is midway orange and red,more orange than red , the background is light grey. Central section is slightly darker grey and coating is a bit flakey in a spiral pattern, so overheated , loosing MO material and going up in resistance. Definitely brown ring, but I assume the colours were red/purple/black originally. Going from 27R to 38R |
All times are GMT +1. The time now is 10:45 AM. |
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 DIYbanter