Results of light bulb current limiter ?

[gtrplayr1976]

OK ...I've connected a lightbulb limiter to an amp I'm trying to repair....25watt bulb....power on...bulb was bright for a second then went to dim,and stayed there. Now what ?

[Jazz P Bass]

Well, now you know the lamp works.
Seriously, what are you repairing.
When powering up any suspect device, it is good practice to monitor the current draw (which you did in a way) & also the power rail voltage of the device under test.
Not knowing exactly what you are attempting to repair, or the symptoms, I am lacking any more advise.

[Wilder Amplification]

The reason it glowed for a second was due to the start up inrush current. Aside from that, I side with Jazz P Bass...without knowing what you're repairing and what you're seeing current draw wise we cannot advise further.

[gtrplayr1976]

Thanks guys. I have another post here for a Crate 165B amp. Enzo suggested the light bulb current limiter to use when I started it. I was having issues ...burning resistors, and fuses when I powered up.

Thanks again

[mooreamps]

Thanks guys. I have another post here for a Crate 165B amp. Enzo suggested the light bulb current limiter to use when I started it. I was having issues ...burning resistors, and fuses when I powered up.

Thanks again

If the amplifier is powered on, and if the lamp is glowing dimly, then this is the indication the amplifier is drawing normal operating current. The bright illumiation at first power on is surge current ; and mentioned below ; and is to be expected.

-g

[macdillard]

take a read here on the use of the light bulb limiter:

Light Bulb Current Limiter

[gtrplayr1976]

Thanks again. I'm hoping it is operating at normal current. I have read that page on the limiter...it helps , but seems it's mostly for tube amps.

thanks , Tom

[gtrplayr1976]

Ok...when I connected the speaker the 25 watt bulb stayed bright, and there is a loud hum. ?????

[stokes]

Why are you using a 25 watt bulb?How many watts is the amp?If the amp is 25 watts or more,you need a bigger bulb.I use a 100 watt bulb for all amps up to 100watts.When your 25 watt bulb stays bright,it indicates the circuit is drawing around 25 watts,which,depending on the amp,may be normal.

[gtrplayr1976]

Why are you using a 25 watt bulb?How many watts is the amp?If the amp is 25 watts or more,you need a bigger bulb.I use a 100 watt bulb for all amps up to 100watts.When your 25 watt bulb stays bright,it indicates the circuit is drawing around 25 watts,which,depending on the amp,may be normal.

Ok..the amp is 60 watts ...so I need a bigger bulb with the speaker connected ....I was just afraid of burning out parts.. it is a SS amp.

I'll try a bigger bulb then.

thanks stokes

[gtrplayr1976]

I put a 75 watt bulb in glows bright , but not 75watts bright. Some of the TPs where I was getting 28-29 VDC with a 40 watt is now 10-13 VDC with the 75watt. I also don't see the power on led lit.

[stokes]

Like I say,I use a 100 watt for all amps.Thing is,you have to get to learn how bright is too bright with different watt amps.I would suggest plugging in a similar "known to be good" amp to see how bright you should expect from a normal,working amp.Oh,and just FYI,it has to be an incandescent bulb,dont use a flourescent.

[gtrplayr1976]

Well..I do use an incandesent bulb. I have a couple of amps I can try. I don't think it's glowing the full 75 watts...I haven't gotten this far with this amp before it would blow the fuse , or a resistor. I'll see if I can find a 100watt bulb. With the 75 watt bulb in the voltage on the board dropped....from 29 to 13 or lower. Why would that happen?

[Jazz P Bass]

"Ok...when I connected the speaker the 25 watt bulb stayed bright, and there is a loud hum. ?????"
There is something wrong with the amp!
Remove the speaker.
Attach your volt meter (set on Vdc)to the amplifiers speaker leads.
Turn on the amp (at this point pick any watt lamp for the limiter).
What Vdc reading do you read at the output?
If you have Vdc, then the output section of the amp is comprimised.

[stokes]

You cant use "any watt bulb you want".Using a 25 watt bulb is too small.Even a 60 watt amp without any problem is going to burn the bulb bright.I'm not saying there isnt a problem with the amp,but using too small a bulb for the amp under test is going to give false results.gtrplayr,when using a current limiter it is normal to see a decrease in voltage in all parts of the circuit.You wont blow any fuses using a limiter,that is the whole idea,you can trouble shoot without blowing a fuse,or any components.When the bulb burns bright it indicates a short someplace,when you find and remedy the culprit,the bulb will dim,but nothing will burn or blow while you assess.