[Jukebox-list] Wurlitzer Amp Blowing Fuse

[Don]

No Problem Jackie. Anytime.
I re-read what I wrote and nearly fell of the chair, convulsed.....

........even tho I was serious about the drastic measure of using the BIG 
fuse to smoke out the culprit.  As Dave Halford said there is a danger of an 
electrolytic blowing up and that is why I recommended eye protection with 
this stunt..... and common sense would also suggest doing this test outside, 
not in the shop.  Also, you wouldn't leave power on for too long before 
turning it off and feeling around the electros and transformers for 
unusually high heat build up.  The last thing you want to do is take out 
your power transformer before the downline damaged component starts to smoke 
or get noticeably hot.  Even this seemingly crude BIG fuse test can be 
finessed.

Bill, you have a serious problem AND if Justin's idea about the bad output 
xfmr turns out to be true AND no one on the list (I'd be surprised if Wes 
and Roy don't have one)  has an exact replacement for it, I have been doing 
xfmr rewind services for several years.  You get back exactly what you send, 
except new wire, new leads, core triple dipped in transformer varnish to 
prevent wire vibration in the windings..... and the xfmr runs cooler than it 
did when new because of improved insulation on today's wire and resultant 
reduction in winding losses that contribute to heat build up.

Good Luck,  Let us know.
Don



----- Original Message ----- 
From: "Jackie" <etreble7 at comcast.net>
To: "Jukebox mailing list" <jukebox-list at lists.netlojix.com>
Sent: Thursday, September 28, 2006 10:12 AM
Subject: Re: [Jukebox-list] Wurlitzer Amp Blowing Fuse


> Don,
> I love your style!
> Jackie
>
> ----- Original Message ----- 
> From: "Don" <dontutt at telus.net>
> To: "Jukebox mailing list" <jukebox-list at lists.netlojix.com>
> Sent: Wednesday, September 27, 2006 11:16 PM
> Subject: Re: [Jukebox-list] Wurlitzer Amp Blowing Fuse
>
>
>> Well.
>> Bill.
>> I am gonna get shot for this, but.......
>>
>> Put in a 30 amp fuse.....   put eye protection in place
>> Turn on....
>> Look and smell for smoke.....  :-(
>>
>> GUARANTEED y'all   'll  find the problem..... fast.
>>
>> Question is....
>> are ya prepared to gamble on destroying something in the process..... 
>> ????
>> on the other hand, maybe it is already "destroyed" or shorted.
>>
>> Good Luck
>> .... and even tho I am 1600 miles away, CALL ME just before you turn on 
>> the power.... 604-824-5711
>>
>> Cheers
>> Don
>>
>> -------SERIOUSLY,  why waste any more time, blow it up (wear eye 
>> protection)
>> ------- we expect a full report, and YES, spelling will count.
>>
>>
>>
>>
>>
>> ----- Original Message ----- 
>> From: "Bill Taylor" <bt_2627 at yahoo.com>
>> To: <jukebox-list at lists.netlojix.com>
>> Sent: Wednesday, September 27, 2006 8:02 PM
>> Subject: [Jukebox-list] Wurlitzer Amp Blowing Fuse
>>
>>
>>> Hi Guys,
>>>
>>> I've been stuck on a problem for a month and can't
>>> find what's causing my fuse to blow.  I'm working on a
>>> Model 1900 with a model 530 amp.  When I start the
>>> amp, the tubes begin for a couple seconds then the
>>> Fuse F4 (2Amp) blows.
>>>
>>> If I pull a lead off C-35A (directly to the rectifier
>>> 5U4 tube), it doesn't blow.  The cap (30mfd 500v)
>>> charges from an ohm meter, but it could be bad so I
>>> bought a new one (although my part source said they
>>> can't get that cap, but use a 47mfd 450 instead that
>>> they've used OK).  I put on the cap, but same problem.
>>>
>>>
>>> So I started to isolate the circuit.  When I was done,
>>> all I had still in the circuit was the output stage
>>> with 2 6L6 tubes push pull ciruit.  Still blows.
>>> Pulled out the tubes, the C-35D cap, and R-77/78  so
>>> thats nothing left except the rectifier, the C-35A
>>> cap, resistors 69A/B (all the big watt resistors), T-1
>>> and T-3.  Still blows after 3 or 4 seconds as the cap
>>> starts charging.  Blows at about anywhere 250-550
>>> volts.
>>>
>>> I looked for any grounds other then the one at the
>>> R-69A/B and they are all isolated.  Both R-69A/B
>>> resistors ohm out correctly when passively tested.
>>>
>>> I'm lost at what to do now.  Anyone with ideas?  Do
>>> you think a transformer can cause a problem like this?
>>> Could those big 15 watt resistors short under load?
>>>
>>> Any ideas, I'm listening!
>>> Thanks!
>>>
>>> Bill Taylor
>>>
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