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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Posted to rec.antiques.radio+phono,sci.electronics.repair
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Converting a positive ground valve/tube car radio to negativeground ?
On Jul 23, 7:35*am, "Brenda Ann" wrote:
"N_Cook" wrote in message ... No user switchable option. I can see its possible to rewire the vibrator so you still get right polarity for the anode supplies. Heaters presumably happy enough powered the other way round but how to change the biasing of the valves ? Unless it's a synchronous vibrator, it should run equally well on either polarity. The radio doesn't get anode voltage from the car's DC, it gets it from the radio's DC-DC converter (vibrator, transformer, rectifier, filtering). Sounds right. But as not in this posting, do recall at least one 12 volt European car radio of the 1950s that had a polarity plug that had to be placed in the correct position. But reading this now can't think why that was necessary! Maybe they were synchronous vibrators or something. BTW not pertinent to this posting but have operate an item of 6 volt DC w. vibrator gear by feeding in 6.3 volts AC from a radio, removing the vibrator and strapping one half of the input winding of vibrator transf. to the supply. So instead of alternatec pulses of DC to each half of the CT input winding, we had 6.3v 60 hertz AC constantly to half the winding. Don't understand the biasing question? |
#2
Posted to rec.antiques.radio+phono,sci.electronics.repair
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Converting a positive ground valve/tube car radio to negative ground ?
In article
, terry wrote: Sounds right. But as not in this posting, do recall at least one 12 volt European car radio of the 1950s that had a polarity plug that had to be placed in the correct position. But reading this now can't think why that was necessary! Maybe they were synchronous vibrators or something. Wonder when transistors started to be used? Hybrid sets were certainly around in the early '60s. -- *I'm pretty sure that sex is better than logic, but I can't prove it. Dave Plowman London SW To e-mail, change noise into sound. |
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