Again, I've found a discrepancy.
Now, regarding the transformers at the EHT block.
My two speakers transformers are differs in colors (the insulating tape's color) and also: layout.
I haven't measured anything yet, but my question is:
Can I harmonise these two to achieve a 'matching pair' or I have to source a transformer?
Now, regarding the transformers at the EHT block.
My two speakers transformers are differs in colors (the insulating tape's color) and also: layout.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I haven't measured anything yet, but my question is:
Can I harmonise these two to achieve a 'matching pair' or I have to source a transformer?
I would not worry about it. There were many variants over the years of production. Measure the output and if they are withing +/5-10% you should be good.
I agree, don't worry about it. You will have two output taps to choose from 590v, and 610v on the one. I think the other one only has 590 if memory serves me right. so you'll adjust the newer one to match the older one and you'll be good. Probably a bigger difference will be the input resistors on the EHT blocks, if they drifted over time, that can change the output a lot. I replace those, and the diodes in the EHT blocks (and I check the caps, but they are very rarely bad; like 2 in twenty years), and finally the neon bulbs and power jack.
Sheldon
quadesl.com
Sheldon
quadesl.com
Thank you for your help, I feel much relieved.
I sourced 2 identical eht boxes from OTA, and swapped the diodes to PH- BY228s. I did not want to exchange the factory capacitors, but I have no way to test them one-by-one.
The two unit's resistors cold-measured the same very precisely, so I hope this won't be a problem. If yes, I will bulid some rectifier boards.
I sourced 2 identical eht boxes from OTA, and swapped the diodes to PH- BY228s. I did not want to exchange the factory capacitors, but I have no way to test them one-by-one.
The two unit's resistors cold-measured the same very precisely, so I hope this won't be a problem. If yes, I will bulid some rectifier boards.
An externally hosted image should be here but it was not working when we last tested it.
Sounds like your power supplies are in good shape. Don't worry about swapping the resistors. I do it when swapping the diodes, just as a preventative measure more than anything. Since you are doing this stuff yourself, if you find something amiss, you can just go back in and track it down. When I'm fixing speakers for others, I err on the side of caution.
Sheldon
quadesl.com
Sheldon
quadesl.com
I will measure the unit's output with the voltage divider and my cheap meter.
I built a 1500mOhm divider as suggested in your book.
I built a 1500mOhm divider as suggested in your book.
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An externally hosted image should be here but it was not working when we last tested it.
These are the measured specs
Thank you. Now, I will have to cosmetically 'refurb' the other supply and I'll measure it, too. I hope they will be close
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I decided to rewire the EHT again, this time for cosmetic reasons only (i know, i know)
But strangely, I measured higher EHT voltages after the procedure:
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