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Old 22nd January 2011, 06:13 PM   #1
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I recently bought a Vintage Victoria Amp(MIJ) 6" speaker (2) 12av6,(1)50C5, and (1)35w4.I talked with a local amp tech over the phone about it and its issues.
This amp works but it does have a few issues.The on and off sw is located with the tone knobs and is finicky but works when jumper is applied.
The volume knob appears to have no effect.
The tone knob seems to be working when amp is running.
Appears to have two different types of hum going on.
There is a slight hot odor when turned on.Perhaps leaky caps.
I asked if I should I add a isolation transformer and was told a hank cord would be alright.
He also mentioned changing out the filter cap and would take care of some of my problems.
Should I change all my caps?????????
I decided to stat with the filter cap.
I went to order my filter cap and cannot find one anywhere.
I really don't know what I am talking about but he said it probably had a 3 stage cap in it.The cap says 60MFD 150WV twice on the cap.Please see pic below.
I have searched and can not find this any where.
Where do I find one??????????
Any added info would be greatly appreciated.
Links to pics below.

Cap in question?
http://i80.photobucket.com/albums/j1...g/100_0093.jpg

Cap in question?
http://i80.photobucket.com/albums/j1...g/IM000749.jpg

Amp front
http://i80.photobucket.com/albums/j1...100_0089-1.jpg

Controls and input
http://i80.photobucket.com/albums/j1...g/100_0086.jpg

Opened rear view
http://i80.photobucket.com/albums/j1...g/100_0084.jpg

Overhead Circuit board
http://i80.photobucket.com/albums/j1...g/100_0080.jpg
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Old 22nd January 2011, 11:09 PM   #2
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A nice little vintage amp, probably easily restored to full working order.

Where are you? It's difficult to recommend suppliers without knowing this.

w
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Old 23rd January 2011, 12:40 AM   #3
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I live in a very small resort town in Northern California called Lakehead.The largest town is Redding which is about 30 miles south and is very limited for finding electronic components.I was planning on buying my components off the internet.
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Old 23rd January 2011, 11:30 AM   #4
korey is offline korey  United States
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Quote:
Originally Posted by boogeyman View Post
There is a slight hot odor when turned on.Perhaps leaky caps.
If you are not very familiar with tubes, the hot smell is probably the tubes themselves.

Quote:
Originally Posted by boogeyman View Post
I really don't know what I am talking about but he said it probably had a 3 stage cap in it.The cap says 60MFD 150WV twice on the cap.
It's actually a two stage filter capacitor. It has two identical stages in one can. You can also buy two individual capacitors to replace the single two stage one.

Be careful with this amplifier as its what's known as a hot chassis, meaning that it has no power transformer, and one side of the mains voltage is live on the chassis. Isolation is a must.

Last edited by korey; 23rd January 2011 at 11:34 AM.
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Old 23rd January 2011, 11:48 AM   #5
SY is offline SY  United States
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Indeed! Running this amp without an isolation transformer is a deadly dangerous, not just for you, but for any innocent person who might touch it.

Quote:
I asked if I should I add a isolation transformer and was told a hank cord would be alright.
This tells you that you're talking to the wrong person.
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Old 23rd January 2011, 12:02 PM   #6
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Quote:
He also mentioned changing out the filter cap and would take care of some of my problems.
Maybe. The hum might be due to a bad filter cap, but it also may be a sign of poor power supply design. I suspect you won't get the hum out of this amp entirely by just changing some caps.

Quote:
Should I change all my caps?????????
No, not necessarily. And by the looks of that amp (it's in really good nick!), I wouldn't change any of the caps before doing some measurements, drawing a schematic and running some simulations on the schematic (esp. the power supply). Troubleshoot any design issues first, then start changing stuff.
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Old 23rd January 2011, 01:02 PM   #7
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This looks like an easy fix if you know what you are doing. I think you could get all the parts to make this amp right, including an isolation transformer for about $50.00 or so. And then there's shipping.
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Old 23rd January 2011, 02:13 PM   #8
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Wow,Thank you for the help!
I have searched the web for a dual 60mfd but was unable to locate one.
I did however find them in 32uf+32uf,50uf+50uf,and 100uf+100uf all at 500v,could i substitute one of these configurations for the 60uf+60uf 150wv.
I also checked rest of the electrolytic caps and I have;
(3) .01mfd 400v
(1) .001mfd 600v or 800v(hard to read I believe it is 600 though)
(1) 3mfd 15v(can only locate 3.3uf 50v would this work for me????)
Is there a certain brand of capacitor that is better than others???????

I really have no idea of what size isolation transformer I would need to add???????
Apparently I got some bad advice about just using a polarized plug.
I am some what fuzzy still on why this would not alleviate the shock hazard.

Mastadon
"taking some measurements, drawing a schematic and running some simulations on the schematic (esp. the power supply)"
Thank you for your advice but this may be a little over my head.
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