Power Supply Experts!! Need help with KEPCO Labs Power Supply

Started by Headbuttking2, June 11, 2006, 09:10:48 PM

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Headbuttking2

I really didn't know where else to turn, and since everyone here seems to know what is going on I figured I would ask this forum.

I have just acquired a 1500 V variable power supply by KEPCO Labs that I am going to use to build/test tube amplifiers..
This thing is huge and is constructed of tubes..

The model # is 1220C and Serial is B-30345

Now my problem is that there are B- and B+ terminals..
Someone machined a BNC plug into the B- port and over the B+ port it says "NC" in marker...

All I can get out of this is a negative voltage (The unit seems to work fine if I want a negative voltage).

The positive terminal must be connected to ground inorder for it to operate..
The positive terminal is connected to the CURRENT meter also.

Here is where I don't understand..
There are massive grey blocks on the chasis..
I can only read one and it says 4 uF at 1000 VDC or 450 VAC, so I don't know if they are all capacitors or inductors. There are 2 smaller ones in the circuit, then the 2 massive ones are on the output. The larges one which is about twice the size of the 2nd largest one produces a negative voltage from a positive one (it has a 1M Ohm resistor across its terminals)..

This is what I observed when I traced the output:

The largest grey block ( I was able to read 4 MFD on the bottom and on the top I can make out "INDUC") has a voltage around 600V on it and as you increase the unit this voltage decreases. There is also a 1M ohm resistor between the terminals of this block.
The 2nd terminal of this block is connected to the negative terminal. This 2nd terminal is also connected to a 2nd grey block. The opposite terminal of this 2nd grey block is where the positive voltage should come from.

I believe someone modified this, because there is a red/white wire coming from the 2nd terminal of the 2nd grey block to the B+ terminal. If it was suppose to be ground wouldn't it be black like the rest of the ground cables?

The insides of this unit are not to hard to trace since it is made of vacuum tubes and there are very few parts, so I traced it the best I could.
On Kepcos website they want $100 for a schematic and service manual which is ridiculous.

Sorry if this post is a little confusing but hopefully someone out there knows a little about vintage power supplys and can help me out here.

I was just wondering if there was away for me to get a positive voltage from this from what I described. Or if someone could just tell me what is going on with this circuitry it would greatly help too.

Thanks in advance.

toneman

I think U are over your head for an electronics project.  :o.   
1500V is way too high for guitar tube amplifiers.
It's also VERY dangerous!!
I'd say, put it on ebay.     :)
Me,... I'll stick to the LowVoltage stuff..   :icon_lol:
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Headbuttking2

Its 0 - 1500V

So I can vary it for the tube amplifier I need..
It wasn't my intention to get a 1500V one, I just wanted one I could use to test designs with..
It is much cheaper then buying a handful of transformers..

HAHA I got this off ebay, and i was the only bidder, so I don't think it would be any use to put it back up, I would just scrap it for parts if worst comes to worse.

toneman

So U got it off Ebay !!   :icon_lol:  :icon_lol:  :icon_lol:

Well,  If half works(?), can U use one half to troubleshoot the other??

Probably will have to reveng the unit.
With tubes it's not that hard...no secret mojo wiring...   :icon_lol:

U might look at another tube pwrsupply...
I would suggest the Heathkit IP-32.
These are great units for practicing with tubes.

Here are some links---
http://bama.edebris.com/manuals/heath/ip32/

http://www.dialcover.com/manuals.html

http://www.vintage-radio.info/heathkit/index.htm

One has several gifs of the manual.
Last one has full schematic of the IP-32.
Heathkit, the company, STILL exists.
They just don't sell kits anymore.
Folks are still selling copies of their manuals on ebay & voilating copyright laws.
U can order a photocopy of any manual thru Heathkit.
An old exhaustgas analyzer manual cost me $15.
What I liked most about Heathkit, was the TheoryOfOperation(TOOp).
Paia manuals were a close second on the TOOp.
Now, the MOTM kit manuals are excellent reading for TOOp.
Have fun with your project!!
Remember to play it safe!! 
BTW, there's a (lower) hiV KEPCO PS on ebay now...#7624485045
afn
T



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TONE to the BONE says:  If youTHINK you got a GOOD deal:  you DID!