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| Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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25th Jun 2020, 6:44 pm
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#21 |
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Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 902
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Re: Hacker RG 300
no just warm [could be just the heat of the day and its sweltering in my garage]
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25th Jun 2020, 6:50 pm
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#22 |
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Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 902
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Re: Hacker RG 300
still confused by the connections on T7 .In the manual it says connect between the collector of T7 and earth.I have one lead on the T7 collector and the other on the chassis [nothing] if i take the lead off the chassis and connect it to the white lead that was on the T7 collector i get a reading that can be adjusted with RV 1
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25th Jun 2020, 10:19 pm
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#23 |
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Dekatron
Join Date: Jul 2007
Location: Evesham, Worcestershire, UK.
Posts: 4,244
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Re: Hacker RG 300
I've never seen one of these in the flesh, but it's possible the metalwork isn't actually connected to ground. I'd recommend getting a ground from the big smoothing cap in the power supply instead.
As it stands, you're measuring between the positive rail and the midpoint. To be honest, either will do the job... If the amp is now staying cool, then perhaps we can believe the 0.02A reading. But that's a lot less than we must have had before, else it wouldn't have got hot. Perhaps it's the weather, but I think I've lost track of what's happening with this - there is uncertainly about the amplifier itself (which might have an intermittent fault), and there is some uncertainty with the measurements... In your shoes, I'd be tempted to use the other meter to measure the current. If the current in the output transistors is genuinely 20mA, and RV2 has no effect, then I think something has changed with that amplifier. If all else fails, you could send the amp to me. But the more you persevere, the more experience you gain... |
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25th Jun 2020, 10:39 pm
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#24 |
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Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 902
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Re: Hacker RG 300
i removed the amp and reconnected the wires to the collectors of both transistors and they got hot again .one thing i did notice is that both amp units seem to be completely insulated from the main chassis.Testing between the chassis and the metalwork of one of the units there is no continuity and looking closely i can see strips of rubber? [some kind of insulation ]between both units .Will do the test again and find a more suitable earth .I will let you know what happens
Anthony |
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25th Jun 2020, 10:44 pm
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#25 |
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Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 902
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Re: Hacker RG 300
just an observation /While the unit was switched on i noticed that the stereo beacon was lit .Quite a novelty to me as i have never known the beacon work on the RG 200 in the house [yes the bulb is ok]
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26th Jun 2020, 9:18 pm
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#26 |
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Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 902
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Re: Hacker RG 300
Well i did the tests again with a known good earth and got the same results .I then swapped the meters over there is no noticeable difference in the readings
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30th Jul 2020, 11:29 pm
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#27 |
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Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 902
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Re: Hacker RG 300
For those of you who are wondering whats been happening with this thread .I have taken mark up on his offer .The amplifier is now with him .I recently found some schematics for the unit that may be of use to him
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