Gotta replace a resistor on my Falcon, need some expert advice about caps.

[BigAlTheBird]

What's up?

So I'm being super careful, we'll start with that. I've read as much as I can (especially from here, and greco) about the dangers of caps. So with that said, there is one resistor that is fried (hopefully the pics show up). I need to replace it, which will be no big deal. But there are two big caps in the way.

I tried draining the caps using the light bulb method, but the thing didn't light up. I'm not even sure they're caps, although they look it (weird place though). So are these resistors? Two have 450V written on it, the big one has 400DC on it.

So can I drain these, or do I need to? I don't wanna get zapped when desoldering the resistor and putting the new one in.

Thanks!

In this picture, the busted resistor is brown, behind the two big black things (that scare me). The other big black one to the right scares me too.

 

[BigAlTheBird]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

Also, that is a 10K resistor, right?

 

[LJ King]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

Also, that is a 10K resistor, right?

If you mean the resistor in between the electrolytics, I see Yellow, Violet, and Brown. That says 470 ohms to me. Notice no "K". It also looks like it might be a 1 or 2 watter... hard to tell from a pic.

It looks like those two electrolytics are cathode bypass caps but it is hard to tell not being able to see their values.

 

[BigAlTheBird]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

I was way off on the resistor, I was just gonna post that. I thought it was white, orange, violet, and then Gold. But it's yellow, violet, and then orange/brown (big difference). Then silver. What a moron.

The big black things say "22 uF" and "450 V"

 

[LJ King]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

No, now the one on the left looks like a B+ filter cap. Really hard to tell what it is connected to...

 

[LJ King]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

I was way off on the resistor, I was just gonna post that. I thought it was white, orange, violet, and then Gold. But it's yellow, violet, and then orange/brown (big difference). Then silver. What a moron.

The big black things say "22 uF" and "450 V"

Yep, 450 volt is B+.

 

[LJ King]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

I was way off on the resistor, I was just gonna post that. I thought it was white, orange, violet, and then Gold. But it's yellow, violet, and then orange/brown (big difference). Then silver. What a moron.

The big black things say "22 uF" and "450 V"

Nope, that third band is brown, not orange. compare to the orange in the third band of the smaller resistor attached to the pot on the left - that's yellow, violet, orange... 470K

Edit: Oops, I meant 47K.

 

[BigAlTheBird]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

By the way, here is the schematic, and the resistor goes between V6 and V7.

 

[BigAlTheBird]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

Nope, that third band is brown, not orange. compare to the orange in the third band of the smaller resistor attached to the pot on the left - that's yellow, violet, orange... 470K

The resistor got burnt, so I'm wondering if the orange got burnt to brown. Just making sure.

And are those caps super dangerous? I'll treat them with due respect no matter what, but I wanna know what I'm dealing with.

I really appreciate the help. I don't want to be crispy tonight!

 

[BigAlTheBird]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

The people on thegearpage told me that 22uF won't hurt, which is what I instinctively thought (since we use 22uF in our guitars, etc., and they don't hurt at all). But I just wanted to make sure.

 

[LJ King]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

The people on thegearpage told me that 22uF won't hurt, which is what I instinctively thought (since we use 22uF in our guitars, etc., and they don't hurt at all). But I just wanted to make sure.

Don't listen to idiots. There is no guitar made with a 22uf for a tone control... that's only about 1000 larger than the 0.022uf you are thinking about.

 

[greco]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

If the cap is over 50V I would be VERY cautious and drain it through at least 1000 ohms (or more) for a few minutes. Don't take any risks.

(This information is from a friend of mine who is an electronics guru)

See what others suggest.

Dave

Edit: Did you make a light bulb cap discharge "system" as was suggested in a previous thread?....this would work well also.

 

[BigAlTheBird]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

If the cap is over 50V I would be VERY cautious and drain it through at least 1000 ohms (or more) for a few minutes. Don't take any risks.

(This information is from a friend of mine who is an electronics guru)

See what others suggest.

Dave

Edit: Did you make a light bulb cap discharge "system" as was suggested in a previous thread?....this would work well also.

I've got the multimeter, so I'll go check it right now. And yeah, greco, I did use the light bulb suggestion you had. Didn't seem to work, but who knows!

Thanks guys.

 

[BigAlTheBird]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

Replaced it safely, hooked everything back together, and nothing. The tubes all light up just fine, but there isn't even a hum or squeak from the speaker. So I'm getting pissed off, because the original tubes (besides the one that broke in shipping) were all supposed to work.

I'm pretty bummed, and pretty pissed. Any other tips?

 

[BigAlTheBird]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

I just realized I accidentally put in a .5 Watt 470 ohm resistor instead of 1 watt 470 ohm. Dammit.

I'll replace it tomorrow, but should it make a huge difference?

 

[greco]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

Check the 0.5 watt resistor after you pull it, just to see if you blew that resistor because the power rating was low. Just out of curiosity.

I can't understand why the light bulb (which acts a large power resistor) didn't work to drain the caps. How did you build/wire it? If you are going to the store to get the resistor you need, you could always buy a power resistor also, and wire it up to drain caps in the future. Certainly is a more "portable" device and no fear of accidentally breaking it.

Keep us informed.

Dave

 

[skyydogg01]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

AL, was that supposed to be a 470 ohm or 47K ohm resistor. look at post 7

 

[Stratman]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

Here is a little thing to help you remember resistor color coding.

Bad, Boys, Rape, Our Young, Girls, But, Violet, Gives, Willingly.

Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Gray, White

1, 2, 3, 4, 5, 6, 7, 8, 9, 10


Yellow = 4
Violet = 7
Red = 100

470 Ohms

0.5 watt if you replace it with a 1 watt no problem, but not the other way around.

 

[muttonchopsrule]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

Here is a little thing to help you remember resistor color coding.

Bad, Boys, Rape, Our Young, Girls, But, Violet, Gives, Willingly.

Black, Brown, Red, Yellow, Green, Blue, Violet, Gray, White

1, 2, 3, 4, 5, 6, 7, 8, 9, 10

:laugh2: :laugh2: :laugh2:

 

[greco]

Re: Gotta replace a resistor on my Falcon, need some expert advice about caps.

Here is a little thing to help you remember resistor color coding.

Bad, Boys, Rape, Our Young, Girls, But, Violet, Gives, Willingly.

Black, Brown, Red, Yellow, Green, Blue, Violet, Gray, White

1, 2, 3, 4, 5, 6, 7, 8, 9, 10


Yellow = 4
Violet = 7
Red = 100

470 Ohms

0.5 watt if you replace it with a 1 watt no problem, but not the other way around.

Doesn't "Our" become Orange (#4) ?

Dave