Tools you WILL need.


These speakers are different and as such you will need more than just a standard toolkit to service them. I provide a list here of things that I have had to buy in order to work on these speakers.

High Voltage Probe - an absolute must. You will NOT be able to measure any of the high internal voltages without some kind of probe specifically designed to measure high voltages. No AVO or DVM can measure 6000 Volts. Also, the power supply in the Quad is wimpy. Any load will cause it to drop in voltage. I use a high impedance probe which drops the voltage by 1000:1. It has an input impedance of 1000 Mohms. I bought mine direct from RS components but you could make your own. It is essentially a voltage divider. If you want to get really flashy you could get an electrostatic voltmeter but these are not easy to find and aren't actually necessary. You could also try using a voltage divider and an insulated gate FET transistor. What you are looking to do is put NO load on the power supply.

Diaphragm Material - If your going to be replacing treble panel diaphragms you will want something to replace them with. You need to get some Polyester film which is 6 Microns thick. Polyester film is sold by different companies under their own trade names - Mylar, Melinex, Hostaphan, Clysar - these are all trade names for Polyester (Polyethylene Terypthalate) film. I would suggest you buy a part used roll. You probably don't want 20 miles of the stuff. Bass panels use 12 micron PVC film which rarely fail. When they do I use Polyester film.

Conductive Coating Material - You are going to need to apply a conductive coating to the surface of the diaphragm. Several coatings have been suggested from various sources. These include wallpaper paste, liquid soap, toothpaste and most popular graphite. Whichever you choose if you haven't done any diaphragms before you will need to experiment.

Stretching Jig - you will need to hold the new diaphragm taught while you apply the conductive coating and while its being glued to one of the stators. Several designs have been suggested including a straightforward frame type which uses bolts to apply tension to the diaphragm, a design which uses a bicycle inner tube which when inflated gives the desired tension and lastly a similar design to the original Quad stretching machine which used several small weights which were hung on the edge of the diaphragm. All these jigs serve three purposes - to apply a tension to the diaphragm, to hold it while its having the conductive coating applied and to hold the diaphragm while its being stuck to one of the stators. Of these designs the first is the easiest for a hobbyist to make themselves but the third design gives the most consistent results as far as diaphragm tension is concerned. Make your own choice.

Component list and suppliers part numbers.

DescriptionSupplierPart No.Where used
High Voltage ProbeRS Components610-281to measure internal voltages
Silver Loaded PaintRS Components101-5621repair arcing damage
Red Heat Shrink TubeRS Components398-278bass panel supply solder post
22 Mohm ResistorRS Components164-8445treble panel supply
10 Mohm ResistorRS Components164-8401bass panel supply
2.2 Mohm ResistorRS Components164-8316input on voltage multiplier
330 Kohm ResistorRS Components149-105input on voltage multiplier
Silicon Diode 1N4007RS Components261-980voltage multiplier
Diode GP02-30 (alternative to above)RS Components195-3551voltage multiplier
10000pf 2kV CapacitorRS Components305-5255voltage multiplier
Heavy Duty PVC Sticky TapeRS Components198-6719around panels to seal them
Isopropanol Degreasing SolventRS Components693-775genral purpose electrical cleaner
Anti-Corona LacquerRS Components569-313inside panels to repair arced area
High voltage internal cable REDArrow Components440023RBass panel power supply
High voltage internal cable BLACKArrow Components447635EBass panel audio signal
High voltage internal cable WHITEArrow Components437637ABass panel audio signal
150 Kohm 2watt resistorArrow Components016314AMCross over
180 Kohm 2watt resistorArrow Components072537HCross over
270 Kohm 2watt resistorArrow Components016320EMCross over
560pf 2kV capacitorMurataDE1507 SL561J2K or
DE0907 R561K2K
Cross over
200 volt Zenner (11 per circuit)RS Components112-4387Protection circuit
Melinex 'S' Polyester Diaphragm Film 12 Micron ThickPSG LtdN/Anew diaphragm material
M3 * 8mm long pan head slotted screwany fixings co.N/Ato hold treble panel together
M3 * 12mm long pan head slotted screwany fixings co.N/Ato hold bass panel together
M3 nutany fixings co.N/Ato hold bass/treble panel together
M3 washer (2 per screw/nut)any fixings co.N/Ato hold bass/treble panel together
Soluble NylonDupont, Hemel Hempsted (01442 218500)Elvamide® 8023RBass and treble panel diaphragm coating
Methanolwww.blackburnmodels.com (do a search for methanol)N/ATo dissolve soluble Nylon


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