just got a 700 ii

Wheel-right

Wheel-right

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#41
That is very nice watts abundant, thanks for posting about it. Always appreciate your knowledge of these things.
 
K-5BLAZER

K-5BLAZER

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#42
yep he has got a wealth of knowledge a good brain to pick I am glad that him and Joe make kits for pl and not some other company they chose right a small compact amp with a boat load of power to get you evicted would not have it any other way. all kidding a side the power to weight ratio is off the charts.
 
MarkWComer

MarkWComer

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#43
K-5BLAZER said:
thats cool but I am afraid I have not been clear enough when I say the switch is broke it is only the mechanical part that is broken the electric part works. when pushed in the meters come on if not held in it shuts off. I think the spring on the switch has been sprung.
Click to expand...
There is a small spring loaded cam within the switch that keeps the button in, releases when depressed again. That latch is the problem.
 
K-5BLAZER

K-5BLAZER

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#44
thanks that is good to know even if it can be fixed when the time comes to work on this thing it will get a new one.
 
K-5BLAZER

K-5BLAZER

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K-5BLAZER

K-5BLAZER

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#49
I could say I thought I saw a different price when I bookmarket it and at my search the prices are all over the place go figure I guess.
 
mlucitt

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#51
MarkWComer said:
Rectifier here:
https://www.mouser.com/ProductDetail/GeneSiC-Semiconductor/KBPC5006T?qs=/ha2pyFadug1dVU7t4Oxhr%2ByN15CV7zlRcd/Ssq5N7diIglh1/8yHw==

Snubbers here:
https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/DME4S1K-F?qs=/ha2pyFaduimK7f/aS8NHg5cItZR4DZDv/iR1Ry2zr5w2EuIukL2iQ==

I guess the fuse holders are okay.
Click to expand...
Careful on the Chinese fuse holders; the body is more brittle than you may be used to, weak springs and inadequate plating. Better to stay with the brand names such as Buss/Bussman or Mil-spec. Something like:
https://tinyurl.com/y7d95w2s
 
Wheel-right

Wheel-right

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wattsabundant

wattsabundant

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#56
I don't know what the justification for changing out the bridge rectifier is. Diodes are incredibly reliable devices due in part to their tolerance of high currents for a short period of time. Generally speaking, a diode will withstand roughly 10 times their average current rating for 1/2 half of a 60 hertz cycle. A properly sized fuse will protect the rectifer due to short circuits or inrush current at turn on.

I've done a fair amount of testing on the inrush current when an amp is turned on. At my house I have recorded up to 150 amps on the first half cycle on 700's. This maximum current is affected by the transformer impedance, the power source and cabling. Based on this, the stock 25 amp bridge rectifier which has a 300 amp surge rating (see attachment ,Page 4, Ifsm) is more than adequate. The 50 amp bridge that was referenced above is 400 amps.

To prove my belief that the stock rectifier is adequate and the 10 amp AC fuse will protect it from inrush current or short circuits, I pulled out the 700B that I used to test the triac modification that I've posted elsewhere. To summarize the mod uses a triac as an on/off switch and the power switch on the amp controls the triac. The mods prevents failure of the switch.

I took a piece of #12 solid wire and shorted out the DC terminals on the rectifier (see photo). This should be a worst case test. I put on my safety glasses, just like always, and proceeded to turn on the switch. The 10 amp fuse blew and it was not an event because the fuse is relatively fast acting. I replaced the fuse and ran the test 2 more times. I then removed the short, turned the amp on through a light bulb, just like always, and the 50 year old rectifier and the amp still works fine (see the other photo). The triac was not damaged because it is rated higher than the fuse.

Conclusion: I'm satisfied that the stock 25 amp bridge rectifier is adequate if the proper AC fuse is used. There may be other reasons for rectifier replacement such as switching characteristics.
 

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#57
this is over my head it just what some people do. I am wondering if instead of using a 50a 600v that every one that upgrades them uses would there be any gains from using a 50a 800v or a 50a 1000v one.
 
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