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Topic: Session 400 Fuse |
William Fraser
From:
New York, USA
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Posted 18 Oct 2012 7:03 am |
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I have an older Session 400 & have a blown fuse ,due to the power lamp falling down in to the amp , a 10 amp came out , so I thought that I should see what the value SHOULD be , Thanks Billy Lee Fraser
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Billy Lee ,Pro-II,, Session 400,Session 500 , Supro , National, SpeedDemons,& too many Archtops & Stratotones.Lots of vintage parts for Kay ! etc. |
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Ken Fox
From:
Nashville GA USA
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Posted 18 Oct 2012 8:31 am
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| 6 amp fast blow, 250 volt (do not use a 32 volt car fuse) |
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Ken Fox
From:
Nashville GA USA
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Posted 18 Oct 2012 12:32 pm
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William Fraser
From:
New York, USA
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Posted 18 Oct 2012 12:45 pm Session 400 Fuse
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THANK YOU KIND SIR , NO SLO BLO , MY 400 LIMITED DOESN'T APPEAR TO HAVE A FUSE , TALK ABOUT COCKY THANKS AGAIN , BILLY LEE FRASER 
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Billy Lee ,Pro-II,, Session 400,Session 500 , Supro , National, SpeedDemons,& too many Archtops & Stratotones.Lots of vintage parts for Kay ! etc. |
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Ken Fox
From:
Nashville GA USA
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Posted 18 Oct 2012 6:10 pm
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| Slo Blo is for tube amps for sure. Fadt Blo, type 3AG or 312 series is common. The Session 400 limited is fused internally at 6 amps |
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William Fraser
From:
New York, USA
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Posted 19 Oct 2012 7:11 am Session 400 THANKS
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Thanks again Mr. Fox , I am curious about what the safe way to make sure the amp is safe to work on re: unplugged amps still being dangerous to handle . Bill
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Billy Lee ,Pro-II,, Session 400,Session 500 , Supro , National, SpeedDemons,& too many Archtops & Stratotones.Lots of vintage parts for Kay ! etc. |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 19 Oct 2012 10:05 am Re: Session 400 THANKS
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| William Fraser wrote: |
| Thanks again Mr. Fox , I am curious about what the safe way to make sure the amp is safe to work on re: unplugged amps still being dangerous to handle . Bill |
Use the tool of pro technicians... the BFS. Take a screwdriver and short the terminals of all the grenade-looking capacitors in the amp. Some folks want you to use a resistor in series... but there's no satisfying 'snap' when you know you've done it right. You can use a jumper lead with a 1K resistor in series if you really must wimp out.
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New FB Page: Lap Steel Licks And Stuff: https://www.facebook.com/groups/195394851800329 |
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William Fraser
From:
New York, USA
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Posted 22 Oct 2012 7:41 am Session 400 THANKS
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Is that a BFS-1 or BFS-2 ? Thanks again for all the help. Bill
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Billy Lee ,Pro-II,, Session 400,Session 500 , Supro , National, SpeedDemons,& too many Archtops & Stratotones.Lots of vintage parts for Kay ! etc. |
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Michael Hummel
From:
Ottawa, Ontario, Canada
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Posted 22 Oct 2012 9:19 am
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Up here in Canada, we use the BFRS (Big F------ Robertson Screwdriver), otherwise known as the "square head". One of the finest Canadian inventions, it comes in four different sizes:
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MSA Classic 5+4
Too many 6-strings and amps to list |
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William Fraser
From:
New York, USA
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Posted 26 Oct 2012 7:30 am Session 400 THANKS
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I have a set of those , & a few thousand screws to go with them , they are used in security applications , & allow you to get things tight & hopefully get them out years later ,try THAT with a phillips or a straight blade , they would work well if you wanted to keep novices from electrocuting themselves working on amps Bill , Thanks to all the kind input , BUT , how long should an amp be unplugged before putting your hands in side , Bill 
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Billy Lee ,Pro-II,, Session 400,Session 500 , Supro , National, SpeedDemons,& too many Archtops & Stratotones.Lots of vintage parts for Kay ! etc. |
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Lane Gray
From:
Topeka, KS
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Posted 26 Oct 2012 8:27 am
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I've heard some of those big capacitors can hold charge for ridiculously long times. Rather than wait for bleedoff, just short 'em. Then you KNOW
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2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects |
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Ken Fox
From:
Nashville GA USA
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Posted 26 Oct 2012 9:17 am
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I never and will never short out a filter cap to discharge it. On a Session 400 the voltage dissipates so quickly it has never been an issue here in the shop. Webb amps takes bit longer to dicharge. For tube amp I bleed the B+ thru a jumper from pin 1 or the plate of a preamp tube. That safely bleeds in thru about 100K or so resistor.
nfo from the internet:
One thing to be aware of is that many aluminum electrolytics - especially vintage ones - don't do so well when they are rapidly discharged. Rapid discharge leads to unusual chemical reactions with the dielectric that release gas and increase the internal pressure of the capacitor. There are special caps made for rapid discharge cycles but the majority of electrolytics should be treated more gently.
While using a lower resistance load to perform a rapid discharge is convenient, I'd suggest going with something a little more conservative and using the extra couple of minutes to head to the fridge for a cold one. I generally use a 25W resistor with 1kOhm per working V of the cap. It takes a little longer but you don't have to worry about damage. Both your gear and your thirst will come out satisfied. |
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William Fraser
From:
New York, USA
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Posted 28 Oct 2012 2:14 pm Session 400 Fuse
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Thank you Mr. Fox that is the safe way not to ruin good caps , I've seen them pop . Lane , I had heard stories of amps that were unplugged a month causing a problem . Thanks Bill
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Billy Lee ,Pro-II,, Session 400,Session 500 , Supro , National, SpeedDemons,& too many Archtops & Stratotones.Lots of vintage parts for Kay ! etc. |
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Richard Sinkler
From:
aka: Rusty Strings -- Missoula, Montana
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Posted 28 Oct 2012 2:36 pm
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| Quote: |
| head to the fridge for a cold one |
What brand would you recommend?
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Carter D10 8p/8k, Dekley S10 3p/4k C6 setup,Regal RD40 Dobro, Recording King Professional Dobro, NV400, NV112,Ibanez Gio guitar, Epiphone SG Special (open D slide guitar) . Playing for 54 years and still counting. |
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Lane Gray
From:
Topeka, KS
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Posted 28 Oct 2012 4:47 pm
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Thank you, Mr. Fox. I've noticed conventional wisdom often has hidden holes it; and I'm glad to learn about 'em.
Richard, I cast a vote for Dos Equis Amber
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2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects |
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Ken Fox
From:
Nashville GA USA
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Posted 29 Oct 2012 5:25 am
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| Glad to share what little I do know! Always something new to learn for myself for sure as well. I picked up that tube amp discharge method from one of Gerald Weber's old books years ago. Sure works well. By placing the jumper to the plate of the tube the B+ will disspate safely (must have standby switch on to get the reamaining B+ voltage that is stored in the caps the plates). Even if ypou forget to remove the jumper on start-up no harm is done, just places a 100K load to ground via the jumper. I use the jumper to plates when trouble shooting noisy plate load resistors in the preamp as well, learned that from the old Weber book as well. Basically the jumper turns the tube off. If the noise goes away then the problem is in that tube stage and likely a noisy plate load resistor. Always start at the first stage of channel gain and then work towards the output stages. |
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Michael Hummel
From:
Ottawa, Ontario, Canada
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Posted 29 Oct 2012 6:51 am
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If Ken says he knows a "little", the rest of us are surely in trouble! He's probably forgotten more than I could even hope to learn.
Mike
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MSA Classic 5+4
Too many 6-strings and amps to list |
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