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Old 13th Jan 2019, 8:54 pm   #1
beachboybuff
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Default Confusion on Capacitor Location in HMV 1508

Evening All,

I am trying to restore a HMV model 1508, and am quite confused about a capacitor in the 3 speed playing unit that is attached only at one end. I can't make out where it should be attached to. I have the schematic, although I can't seem to follow it while referring to the actual circuit. It is possible I am reading the schematic wrong, or that it has been modified at some point, which is leading to my confusion. The capacitor in question is they grey one in my pictures, of 0.0022μF. In the diagram it shows it to be before TR3, although looking at the circuit it is wired to the same point as C29. I can't see any obvious points where it has snapped off from either. Any tips or advice would be great.

Thanks,

Michael
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Old 13th Jan 2019, 8:56 pm   #2
beachboybuff
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Default Re: Confusion on Capacitor Location in HMV 1508

Some more pictures, as it is quite hard to convey a representation of the circuit with a few photographs.
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Old 13th Jan 2019, 11:09 pm   #3
Nuvistor
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Default Re: Confusion on Capacitor Location in HMV 1508

It appears to be C32 connected across the heater supply winding of TR3. The grey capacitor is a mixed dielectric type, I would replace it it, mixed dielectric are known to be unreliable.
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Old 19th Jan 2019, 7:37 pm   #4
beachboybuff
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Default Re: Confusion on Capacitor Location in HMV 1508

Hi Frank,

Thanks for your reply. Does that mean that the capacitor is currently in the wrong position, as one lead was already attached to C29, where it does not show this in the schematic? I only ask because I was having trouble following the schematic for the 3 speed playing unit part of the set, and wondered if the schematic could be for an earlier or later model.

Regards,

Michael
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Old 19th Jan 2019, 10:31 pm   #5
Nuvistor
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Default Re: Confusion on Capacitor Location in HMV 1508

The circuit I have from R&TV as far as I can tell shows both capacitors connected to chassis.
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Old 20th Jan 2019, 7:59 pm   #6
Silicon
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Default Re: Confusion on Capacitor Location in HMV 1508

Michael, that black bodied resistor soldered to the tag strip in the first photograph may be a thermistor.
They often have high voltage AC/Mains voltages on them.

If it is, it could get very hot and melt the insulation of the nearby wires.
You may then get mains voltages where you don't want them.
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