roy51
Society Members
If it ain't broke, fix it anyway
Posts: 96
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Post by roy51 on Aug 30, 2021 18:36:52 GMT 12
Wow !!! What a fantastic job, well done, looks great
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Post by DHockey on Aug 31, 2021 8:50:51 GMT 12
The regulator looks great! I may tidy mine up with a cover like that.
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Post by Philconut on Oct 15, 2021 21:11:55 GMT 12
I have finally got the front panel completed and the instrument reassembled. It took most of yesterday by the time I had checked & double checked the wiring. Today I started on the testing of the various functions. Some minor adjustments to resistors were required otherwise everything seems to be working. There is a discrepancy on the ohms range which needs some investigation. I am still quite in the dark about the value of C3 which is across the DC supply on the "Line Adjust" and "Electrolytic" functions. I originally had it at 0.47mfd which set the Line Adjust at mid tap but that gave 35V on the Electrolytic 25V test. I now have it at 0.33mfd which shifts the Line Adjust three taps but the DC voltage on the Electrolytic 25V test is still 30V. If I reduce the value further to correct the electrolytic voltage I run out of taps on the line adjust? - a bit of a quandary. I think I will try setting it up with a valve in place and measure the heater voltage. This will set the correct tap, then I will have to work on the Line Adjust & Electrolytic tests. Anyway, lots of progress with encouraging results.
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Post by Philconut on Oct 19, 2021 21:16:06 GMT 12
All done. It turns out that the heater volts were about 0.5V too low. I found that I had reversed two wires to the heater pins of the valve sockets. I haven't followed it through but it seems that the reversal caused a subtraction on the heater volts circuit. With these the correct way around the heater volts came right and with C3 at 0.5uf the line adjust is correct too. The 25V electro range gives 27V so I am a happy chappy! It really is a clever piece of kit and I too will make good use of it. I'll post some photos when I have assembled it.
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Post by DHockey on Oct 20, 2021 7:07:41 GMT 12
That’s great news John. Glad you got the electro test sorted out. The 25V test on my unit also puts out 27V – 30V depending on where the line adjust is set. When I set mine up, I used the 6X5 heater voltage as the reference for the line adjust. When I had 6.3V – 6.4V on the 6X5 socket I was getting 1 division shy of FSD on the meter, which is good enough for me. I did try playing around with the resistors in the line adjust circuit, but just ended up chasing my tail and left it with the “factory” values. I found the normal setting of the line adjust to be the 11 or 12 o'clock position.
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Post by Philconut on Oct 20, 2021 8:00:55 GMT 12
Yes my Line Adjust is at 11 o'clock. I used the 6.3V of the main winding but I did plug in a 42 for some load. I just noticed yesterday that the UX7 socket is the larger one for a 53, 59 etc. I will have to make an adapter for the smaller UX7 socket.
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