Resistance checks on FPIII

[Neuronal]

I'm trying to win the award for to be the very last person in the world to construct a new FPIII - had it in the garage, finally getting around to building it now (I'll be working on a similar award for the Paramounts in about a week). Got through the build of the base unit (not extended), took resistance checks, all looks great except the transformer measurements. PT 1,2,6,7,9,10 were (according to the manual) all supposed to read infinity; instead 1 and 2 read zero (true zero, not point anything), and 6,7,9,10 are all variable and equal to each other (varies from 10s to 100s kOhms). Is this ok to power up or did I do something profoundly wrong? Thanks so much for your help - I built a SEX amp 10 years ago, and now am planning in the next month to get through this, the paramounts and a seduction. I know I'll be on this forum asking all sorts of newbie questions about very old equipment, so thanks to all for your patience with me and for creating such a wonderful community.

 

[Paul Joppa]

Don't fire it up!

Transformer pins 1 and 2 should be connected to the power inlet socket and switch, which must be isolated from the chassis for safety. So something is not right. A photo of the transformer wiring might help.

I am also worried that both measure zero - there should be a few ohms difference between them. What resistance range was used for that measurement?

 

[Neuronal]

Thanks for the warning! So I went back and checked these again. I have an autoranging Fluke 179. In autorange mode and across all of the possible manual ranges, the meter reads "OL" at PT1 and PT2; this is the same if the meter isn't measuring anything at all, so I guess that is infinity rather than zero? If I measure resistance across PT1 and 2, it reads about 11 ohms. If I look for continuity between PT1 and the PEM with the power switch off, I find continuity with the black wire on the PEM but not the red or the ground; if the power switch is on, I find continuity with the black and red wires but not the ground. I see the same pattern if I test for continuity with PT2. I've attached pictures of the wiring the best I could take with my crappy iPhone.

I guess the other thing I'm wondering about is whether the other PT terminals (6,7,9,10) are supposed to float around like that.

Thanks again for your help - sounds like you prevented a lot of smoke!

 

[Paul Birkeland]

"OL" is over limit, not zero.

 

[Neuronal]

Am I ok then?

 

[Paul Birkeland]

Do your power transformer terminals read 0 ohms?

 

[Neuronal]

PT1 - OL
PT2 - OL

PT4 - variable, 10s-100s kOhms
PT5 - identical to whatever PT4 is at a given moment

PT6 - variable, 10s-100s kOhms, different from PT4
PT7, 9, 10 - identical to whatever PT6 is at a given moment

If "OL" = infinity, then according to the manual PT1, 2, 4, 5 are all normal. But PT 6, 7, 9, 10 are supposed to be infinity, and they are instead co-varying over time.

Thanks again for thinking about this problem - it is much appreciated.

 

[Paul Birkeland]

None of your power transformer terminals read 0. 

Go ahead and power it up.

 

[Neuronal]

Thanks! Excited to take voltages tonight. I'll let you know how it goes

 

[Neuronal]

Fired up, voltages are dead on, sounds great!!! OK, now onto the Paramounts

Thanks to all for their help with this - gives a newbie like me courage to know there is back up!

 

[Paul Birkeland]

I would definitely toss the LEDs in a kit that old, especially when there are a bunch like the Paramount has.  This is of course unless you live in a very, very dry environment.  If your kits have been sitting around in a garage in Yuma, AZ or Las Vegas, everything should be fine. 

 

[Neuronal]

cool, I'll write to order replacements now. Thanks again for your help.....