Help!

littlerick · 20th February 2010, 01:17 PM

Please check my problem here.

LM4870 Noob mess up

geraldfryjr · 20th February 2010, 01:32 PM

acording to your pics you have bare wires all over touching each other and the chassis.do you have any with it compleated? jer

littlerick · 20th February 2010, 01:35 PM

Only transformer and rectifier are connected together at the moment. was gonna connect amps if rectifier was ok. its not

john blackburn · 20th February 2010, 03:28 PM

Hi littlerick.

What setting did you have your meter on when testing the rectifier? Are you certain you have your secondaries paired up correctly?

What AC voltage is showing on your secondaries with the rectifier board connected, and what happens with your bulb tester when the power is applied?

John

littlerick · 20th February 2010, 04:02 PM

Meter is set to DC 200v... I have them wired in the colour pairs that it states on label... It is still showing 24.5v at each transformer output....

I didnt use lightbulb tester... Not got round to makin it yet, but I guess I should.

pacificblue · 20th February 2010, 11:25 PM

Sparks and the light bulb growing bright sounds like a short-circuit. If that happens when you place the probes, you are either shorting something with either of the probes or you have the probe wires connected to the wrong input of the meter. If the probes are connected for current, you will produce a short through the meter no matter which DC voltage range you set.

littlerick · 20th February 2010, 11:31 PM

my multimeter has 3 probe inputs.. 1 for negative.. and 1 that says VrmA (r being ohms) and the other says 10ADC.

I have it in 10ADC and dial set to DCV... DCV has 5 settings 200m, 2000m, 20, 200, 1000. I have it set on 200. Is this right?

pacificblue · 20th February 2010, 11:53 PM

NO. If you want to measure DC V you need to plug the probe into VRmA (V=voltage, R= resistance, mA= milliAmperes). The ADC connector has nearly 0 impedance towrads the negative connector and produces a short circuit across the board. It could well be that the A range of your meter is fried now.

littlerick · 21st February 2010, 12:03 AM

Maybe I should take up cooking... Frying seems to be my special talent.

Its 1am now, I'm gonna go bed n sleep on it.. Thanks for the help guys, maybe get it right on a fresh day!

geraldfryjr · 21st February 2010, 04:32 AM

naw,keep building we all hit a learning curve sometimes! jer

20th February 2010, 01:17 PM	#1
littlerick diyAudio Member Join Date: Nov 2009 Location: Lincolnshire UK	Help! Please check my problem here. LM4870 Noob mess up

20th February 2010, 11:25 PM	#6
pacificblue diyAudio Member Join Date: May 2008	Sparks and the light bulb growing bright sounds like a short-circuit. If that happens when you place the probes, you are either shorting something with either of the probes or you have the probe wires connected to the wrong input of the meter. If the probes are connected for current, you will produce a short through the meter no matter which DC voltage range you set. __________________ If you've always done it like that, then it's probably wrong. (Henry Ford)

20th February 2010, 11:53 PM	#8
pacificblue diyAudio Member Join Date: May 2008	NO. If you want to measure DC V you need to plug the probe into VRmA (V=voltage, R= resistance, mA= milliAmperes). The ADC connector has nearly 0 impedance towrads the negative connector and produces a short circuit across the board. It could well be that the A range of your meter is fried now. __________________ If you've always done it like that, then it's probably wrong. (Henry Ford)

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20th February 2010, 01:32 PM	#2
geraldfryjr diyAudio Member Join Date: Feb 2008 Location: Jackson,michigan	acording to your pics you have bare wires all over touching each other and the chassis.do you have any with it compleated? jer

20th February 2010, 01:35 PM	#3
littlerick diyAudio Member Join Date: Nov 2009 Location: Lincolnshire UK	Only transformer and rectifier are connected together at the moment. was gonna connect amps if rectifier was ok. its not

20th February 2010, 03:28 PM	#4
john blackburn diyAudio Member Join Date: Sep 2006 Location: Wirral UK	Hi littlerick. What setting did you have your meter on when testing the rectifier? Are you certain you have your secondaries paired up correctly? What AC voltage is showing on your secondaries with the rectifier board connected, and what happens with your bulb tester when the power is applied? John

20th February 2010, 04:02 PM	#5
littlerick diyAudio Member Join Date: Nov 2009 Location: Lincolnshire UK	Meter is set to DC 200v... I have them wired in the colour pairs that it states on label... It is still showing 24.5v at each transformer output.... I didnt use lightbulb tester... Not got round to makin it yet, but I guess I should.

20th February 2010, 11:31 PM	#7
littlerick diyAudio Member Join Date: Nov 2009 Location: Lincolnshire UK	my multimeter has 3 probe inputs.. 1 for negative.. and 1 that says VrmA (r being ohms) and the other says 10ADC. I have it in 10ADC and dial set to DCV... DCV has 5 settings 200m, 2000m, 20, 200, 1000. I have it set on 200. Is this right?

21st February 2010, 12:03 AM	#9
littlerick diyAudio Member Join Date: Nov 2009 Location: Lincolnshire UK	Maybe I should take up cooking... Frying seems to be my special talent. Its 1am now, I'm gonna go bed n sleep on it.. Thanks for the help guys, maybe get it right on a fresh day!

21st February 2010, 04:32 AM	#10
geraldfryjr diyAudio Member Join Date: Feb 2008 Location: Jackson,michigan	naw,keep building we all hit a learning curve sometimes! jer

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