Viz WP 707A Lab power supply - Page 1
Forum section: electronics / testgear

author: Mysion
author_rank: Regular Contributor
timestamp: August 23, 2013, 01:14:01 am
content: Just bought a Viz wp 707a on ebay for about 70$ with shipping so I thought I would share some photo's with you guys!It's not as nice as an HP one but I like the dual supply. (Yes I know HP made dual supplys but they cost more)I suspect the small transformer on the left is for the front panel display.It's all working. Mostly. The voltage is close enough although on the right supply it reads .01 volts high. I want to trim it but I have no idea where to do it....Some times LED segments refuse to turn on but rapidly powering it on and off fixes it. A bit disturbing.However the current control is really funky... (In a bad way). You can turn the knob to adjust, however there's no feed back on the display to what it's set too. Also when you do go above the set limit the whole supply shuts off. I would rather it keep it on, just prevent any more current from being drawn.I can't find a manual for it (surprise surprise). It might be fun to try and make a schematic for it. I might take a shot at it.

author: MickM
author_rank: Regular Contributor
timestamp: August 23, 2013, 08:00:57 pm
content: Hi;I have a "WP 708".Try removing the led board and re-seating the displays in their sockets.Mine had worked a bit loose.Each channel has a reset button.(red button top left, and top right).Just remove the problem (or up the current), and push the button.That will enable that channel again, no need to turn it off and on.The switch labelled 'A/V' is for the output.Set the V then switch to A to see the output current.The switch labelled "Measure" switches between measuring the output or becomes a DVM.So you have two DVM's seperate from the supply.Mine goes to 20v/2A two channels and has a fixed 5V supply.Great supply except that the rotary switch is backwards, rote it eft and it RAISES the voltage.Mick M

author: rbola35618
author_rank: Frequent Contributor
timestamp: August 23, 2013, 09:21:00 pm
content: The predecessor to VIZ was RCA (Radio Corporation of America). Worked for them fixing TVs for 13 years!Robert

author: Mysion
author_rank: Regular Contributor
timestamp: August 24, 2013, 07:58:32 pm
content: MickM thanks for the advice. I discovered the reset button soon after I wrote that but it still seems wonky. It's hard to miss there's to big warning stickers about it on top of the unit.Thankfully the rotary switch direction doesn't bother me because this is the first supply that I've used. It looks like it would be easy to modify it to go in the right direction but modifying antique test equipment just...... feels so wrong.....Any ways I started making a schematic. I figure it would be a good learning exercise( and fun) and all I can say is holy crap that transformer has a lot of taps and separate wingdings!

author: The_PCB_Guy
author_rank: Regular Contributor
timestamp: March 18, 2014, 10:20:01 pm
content: I don't usually resurrect old threads but I thought I'd mention I just bought one of these (Just a 707) on Ebay for $33 USD including shipping. It's in worse shape than the one in the first post, but I am thinking it would be a fun restoration project. I would have preferred one that can supply 5 or 6 amps, but 2A will work for most of my projects.Here are some pics:Thanks for posting,Matt