[Fiola]

I recently completed my Millett hybrid using tread as psu. When plugged in alone, the tread seems fine, measures all good, and LM317 is warm but not hot at all. plug the tread into MH, the lm317 gets really hot, i measured using a probe to be around 100 degrees. Is this normal operation? I thought i might've done something weird with my MH, so i measured between the +V and ground pad where the tread's leads would connect to, and with the tubes in measures to be around 26 ohms. That seems.... a bit low? is this normal?

Everything else seems to be alright, It sounds fine, highs are slightly harsh for some reason, maybe cuz im using Nichicon UPW for C7 caps, goign to swap them out for something better later.

Thanks in advance

 

[ozshadow]

I think this is going to depend on the input power, the outputted power, and the current consumption of the amp as to how hot the chip will get. Sometimes the chip needs a heatsink.

 

[grasshpr]

Quote:

Originally Posted by Fiola I recently completed my Millett hybrid using tread as psu. When plugged in alone, the tread seems fine, measures all good, and LM317 is warm but not hot at all. plug the tread into MH, the lm317 gets really hot, i measured using a probe to be around 100 degrees. Is this normal operation? I thought i might've done something weird with my MH, so i measured between the +V and ground pad where the tread's leads would connect to, and with the tubes in measures to be around 26 ohms. That seems.... a bit low? is this normal? Everything else seems to be alright, It sounds fine, highs are slightly harsh for some reason, maybe cuz im using Nichicon UPW for C7 caps, goign to swap them out for something better later. Thanks in advance

What kindof transformer are you using for your tread (Specs wise that is)? Is the transformer also heating up?

 

[Fiola]

oh right, forgot to mention the important details

Tread has a AC - AC wallwart coming in rated at 26VAC 700mA
measures to be 28VAC unloaded

Tread is configured to give out 26V DC

 

[tomb]

A quick check of your numbers using Tangent's power parameter calculator yields 50-80 deg.C. above ambient with a reasonable heat sink. If you are reading Celsius temperature, 100deg. is about right.

This may be a cause for worry if you case it up, and you should definitely add a heat sink. However, I don't think anything is operating incorrectly.

About the Nichicon - speaking from experience as power caps, the 470uF may need about 100 hrs or more before they quit sounding harsh. A different cap may indeed sound better, especially for C7, but you may still have just as long a break-in period before you find that out. I would give it more time just yet.

 

[grasshpr]

If your temperature is about 100 degrees Fahrenheit, then that sounds just about right based on the transformer specs and output voltage. Maybe it should turn out a bit higher depending on your heatsinking option.

 

[robzy]

How much current is the millet drawing? That is a lot more important than transformer specs if the transformer is not heating up.

Rob.

 

[Fiola]

Transformer seems to be doing fine, i can hold the wallwart in my hands no problem. Current draw from millett is around 168mA. I guess it looks like everything is in order, and I will probably want to add a heatsink to my LM317 eh?

 

[grasshpr]

Yeah, that sounds about right for millett, possibly even a bit higher current depending on load. If you didn't have heatsink on, you might wanna put it on.