Another WOPL 700b is born !

Vintage 700b

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#1
Hello Guys,
I have gotten a lot done the last several days and have the entire 700b back together. Everything checks out, Bias at .360/.360, DC Offset .0001/.0000. Relay board works perfectly. I have everything finished up but I installed a new LED Board, and I have no lights! Of all the things to be dealing with. I have Pad 14 and 15 populated with the low voltage side of the transformer (5.7v each). On/Off switch,and the inputs/potentiometers are working as they should, the 20db switch is fine. I had slight needle jump when I brought the entire assembly up (DBT and Variac) so the front board seems to be fine, except for no lights. It's frustrating to get this far, and one final thing to figure out.
I was looking at the front panel a week ago, figuring what my strategy would be, after initial bring up. I could not figure out what populates Pad 4 on that board, which may be my issue with the lights. I have run a gray wire, as the instructions mention pad 4 uses a gray wire, but where does the other end of that gray wire from Pad 4 go to? I do not see a run on any schematic that I have. The ironic thing with this particular amp is, the original board that I removed worked perfectly, and bulbs lit when the unit was on. I'm tired, been installing a lot today, started with 5 rows of transistors, had one in last night,, so I may need a nudge to see the forest for the trees. If anyone has a suggestion or two, I would appreciate it. I wanted to get the lights sorted out before I start to do any signal tests.
Thank You,
 

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Gepetto

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#2
Hello Guys,
I have gotten a lot done the last several days and have the entire 700b back together. Everything checks out, Bias at .360/.360, DC Offset .0001/.0000. Relay board works perfectly. I have everything finished up but I installed a new LED Board, and I have no lights! Of all the things to be dealing with. I have Pad 14 and 15 populated with the low voltage side of the transformer (5.7v each). On/Off switch,and the inputs/potentiometers are working as they should, the 20db switch is fine. I had slight needle jump when I brought the entire assembly up (DBT and Variac) so the front board seems to be fine, except for no lights. It's frustrating to get this far, and one final thing to figure out.
I was looking at the front panel a week ago, figuring what my strategy would be, after initial bring up. I could not figure out what populates Pad 4 on that board, which may be my issue with the lights. I have run a gray wire, as the instructions mention pad 4 uses a gray wire, but where does the other end of that gray wire from Pad 4 go to? I do not see a run on any schematic that I have. The ironic thing with this particular amp is, the original board that I removed worked perfectly, and bulbs lit when the unit was on. I'm tired, been installing a lot today, started with 5 rows of transistors, had one in last night,, so I may need a nudge to see the forest for the trees. If anyone has a suggestion or two, I would appreciate it. I wanted to get the lights sorted out before I start to do any signal tests.
Thank You,
Closeup pictures of your wiring to the light board please.

Gray (sometimes black) wire on PAD4 is a ground wire that runs to the single point ground between your bulk caps. That wire does not affect the LED lighting however, it affects meter operation. The only thing you need to get lights is the 5.7VAC measured between PAD14 and PAD15.
 
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Vintage 700b

Chief Journeyman
Joined
Mar 13, 2019
Messages
741
Location
Wisconsin
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Fabricator
#3
Here is a quick picture of the board, the two green wires go to the low voltage side of the transformer. They measure 5.7v each at the light board ( on pad 14with a full 120 v input line.
Sorry, can't post the picture this way. Will work on it tomorrow.
Thank you
 

Gepetto

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#4
They measure 5.7v each at the light board ( on pad 14with a full 120 v input line.

I am not comprehending what this means as written. They should not measure 5.7V each, they should measure 5.7VAC when you measure from PAD14 to PAD15 with your DMM.
 

Vintage 700b

Chief Journeyman
Joined
Mar 13, 2019
Messages
741
Location
Wisconsin
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#5
Hello Guys,
I apologize for the typo last night Joe. I was on my way to bed, had been up since before 5am and worked all day getting the amp squared away. I took a picture of the board to post and the computer and phone would not work together. I threw my hands up and went to bed. This morning, refreshed, I went back in, and tested the transformer terminals, and I did have one of the green wires that I ran for the 5.7v soldered to the wrong post. I had 5.7v and 1.4v. Checking the other transformer post I would have 5.7 across them. I switched the one wire at the transformer, and I have everything working as it should. I am currently listening to a 1959 6 eye recording of Miles Davis' Kind of Blue through the amp....amazing!!!!! I may not leave the living room today!
I knew it was something small last night, I was just out of patience and so tired. It had been a good day, and today, I am still amazed at how clear this album sounds compared even to my other stock 700b. I have the relay and light board, with new bulk caps in that one, stock backplane, and driver board. I unhooked it, to hook this WOPL 700b up.
Thank You for all of the support and help. The quality of the components, directions, and logic in the boards is first class. That has made this rebuild extremely enjoyable, I can't thank you and the Phoenix group enough. I will definitely be going through the other 700b, but just for today, I am enjoying the music! That's what it's all about!
Have a great day everyone,
Thank You
 

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