Alpine 3545 blows all fuses after 5 seconds of power

[bmore5077]

More awesome info. Thanks again

 

[bmore5077]

I found a place in pa that has the transistor I pulled that was bad. Here is the link
2SC3182
Is that company reputable. Thanks

 

[Perry Babin]

I've used them a few times and haven't had any problems.

You can't replace only one of the outputs. At the very least, you have to replace all 3 of the same part number in that channel.

Also confirm that all 3 emitter resistors for those transistors are within tolerance.

 

[bmore5077]

Will do....figured I'd do all 3 as well. I looked at the part numbers you gave me. The transistor that was bad was npn,,you gave me part numbers for npn and pnp. What would you replace if I go to the new part numbers you gave me. Thanks

 

[Perry Babin]

I would replace all 6 in that channel. There is a very slight chance that the alternate part number parts could be incompatible but I've never had a problem with them.

Find the other problems (hissing, leaky caps..) before buying output transistors.

 

[bmore5077]

Will do... thanks

 

[bmore5077]

Hello I looked closer at the caps and it looks like these are maybe the filter caps but these look like maybe they leaked. It not gooey.. it's crusty but looks more black then brown. Was trying to find replacements but these are vt (m) stamped which looks to be obsolete. I attached a picture for advice. Thanks

 

[Perry Babin]

I would remove that fixative. The caps are likely OK.

 

[bmore5077]

Ok so I tried to do adjustment from service manual. Was able to adjust supply voltage to 104 but idle current I'm getting zero on both test points. Not sure if I'm doing something wrong or what. The bad transistor is stil removed from circuit board if that matters.

 

[Perry Babin]

Check for audio. Measure across the speaker terminals for each channel to confirm that the DC voltage is well under 1v. If so, connect a speaker to one channel at a time to see if it's producing clean audio.

 

[bmore5077]

Audio sounded good on the side with all the components. Nothing fron side with transistor removed as expected. Thanks

 

[Perry Babin]

It should play. It could have dirty switch contacts. Move all external controls while listening for audio.

 

[bmore5077]

Plays audio but real low on th side without transistor

 

[Perry Babin]

That has nothing to do with the missing transistor. Think of a tractor with 3 wheels/tires on each corner. The tractor will work perfectly fine if you remove one wheel/tire from any corner. That's this amp with one output missing.

 

[bmore5077]

Ok that analogy works for me. Thanks for the explanation. I starting moving things lightly and found the rca jack just be a little loose. Now plays same level and fine. Still have that low hissing from I believe power supply though

 

[bmore5077]

That's why I was trying to adjust the idle current but I set my meter to v to read mv and get zero both sides. Not sure what I'm doing wrong. I can tell you the pots on both sides are either all the way up or down. Wish I knew which way to turn them for adjusting up or down.

 

[Perry Babin]

Is the meter auto-ranging?

 

[bmore5077]

Yes it is

 

[Perry Babin]

Do you see a difference if you read leg 1-3 on any of the output transistors when you adjust the bias pot?

 

[bmore5077]

Oddly the voltage is about .45 and rises when I turn the pot. What's wierd is the transformer noise gets lower as I turn it up. Didn't turn that much because I was scared to hurt something. I guess tommorrow I'll have to find a way to read and adjust the idle current. Thanks again for all your help..couldnt get to here without you.