Testing a Wearite tape deck question - UK Vintage Radio Repair and Restoration Discussion Forum

pentoad · 12th Jul 2020, 3:18 pm

This deck has a hold down solenoid (330 ohms) which energised from the HT circuit of the amplifier (between the speaker primary and previous gain stage)
I do not have the record replay amplifier.
I don't know what power it requires to actuate it.
In order to test the deck I have an adjustable HT power supply source which is okay for 250vdc, how do I go about simulating the impedance load of the el84 output stage so the current draw is correct for the solenoid?
Or do I apply a low voltage and then adjust it until it is sufficiently magnetised?
I don't want to burn the solenoid out as they are unavailable

ms660 · 12th Jul 2020, 8:02 pm

That seems to tally up with the solenoid in the Ferrograph Series 4 deck, that has a nominal voltage drop of 14 volts.

On playback...HT in = 278 volts, HT out = 263 volts (15 volts drop)

On record...HT in = 240 volts, HT out = 223 volts (13 volts drop)

You can do the Ohms law from that for a series resistance for whatever supply voltage you decide to use.

https://www.vintageshifi.com/reperto...Ferrograph.php

Lawrence.

pentoad · 14th Jul 2020, 2:54 pm

Thank you for your help

12th Jul 2020, 3:18 pm	#1
pentoad Hexode Join Date: Feb 2011 Location: Newcastle upon Tyne, Tyne and Wear, UK. Posts: 280	Testing a Wearite tape deck question This deck has a hold down solenoid (330 ohms) which energised from the HT circuit of the amplifier (between the speaker primary and previous gain stage) I do not have the record replay amplifier. I don't know what power it requires to actuate it. In order to test the deck I have an adjustable HT power supply source which is okay for 250vdc, how do I go about simulating the impedance load of the el84 output stage so the current draw is correct for the solenoid? Or do I apply a low voltage and then adjust it until it is sufficiently magnetised? I don't want to burn the solenoid out as they are unavailable

12th Jul 2020, 8:02 pm	#2
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Testing a Wearite tape deck question That seems to tally up with the solenoid in the Ferrograph Series 4 deck, that has a nominal voltage drop of 14 volts. On playback...HT in = 278 volts, HT out = 263 volts (15 volts drop) On record...HT in = 240 volts, HT out = 223 volts (13 volts drop) You can do the Ohms law from that for a series resistance for whatever supply voltage you decide to use. https://www.vintageshifi.com/reperto...Ferrograph.php Lawrence.

14th Jul 2020, 2:54 pm	#3
pentoad Hexode Join Date: Feb 2011 Location: Newcastle upon Tyne, Tyne and Wear, UK. Posts: 280	Re: Testing a Wearite tape deck question Thank you for your help