Looking at a picture of the bottom with the cover removed it looks pretty simple with a choke input power supply ,whats the problem ?
Bill in the USA has retired (Morningstar -import company ) although its designed by Alex Yeung who owns EE which WAS in Hong Kong --it too is out of business.
Bill himself verified that and says he is "tired at (now ) 66"--- his post brought my admiration --VERY nice guy !
As I said it looks pretty simple .
Bill in the USA has retired (Morningstar -import company ) although its designed by Alex Yeung who owns EE which WAS in Hong Kong --it too is out of business.
Bill himself verified that and says he is "tired at (now ) 66"--- his post brought my admiration --VERY nice guy !
As I said it looks pretty simple .
Hi Duncan. I have someone repairing or for me, who can repair it. It's just that a new mains transformer is needed, several of the wires are disconnected, and it's got a soft start circuit that is a bit different, and not the most easy to get at and see.
So it works be very useful and easier to confirm the transformer my repairer worked out we need wound, and work out the circuit. Trying to make his life as easy as possible.
Cheers David
So it works be very useful and easier to confirm the transformer my repairer worked out we need wound, and work out the circuit. Trying to make his life as easy as possible.
Cheers David
The EZ90 outputs 70ma at a input RMS voltage of 325-0-325 volts --maximum capacitance 16uf -minimum series resistance 525 ohms and 6.3 volt at 0.6 amp heaters .
So that takes care of the high voltage supply and --separate --heater supply for the transformer .
Three ECC83 valves -each 1.2ma anode current per side ( twin triodes ) so at least 10ma HT and 250 volts supply to them at a total of (approx) 1 amp heater supply.
Thats pretty simple and a light load for a mains transformer ,any thing else like the soft start is after the power supply or additional to it .
Is the soft start faulty or disconnected ?
Thats the only part that might need a circuit diagram as there isn't a standard one unless you buy a module on eBay etc.
So that takes care of the high voltage supply and --separate --heater supply for the transformer .
Three ECC83 valves -each 1.2ma anode current per side ( twin triodes ) so at least 10ma HT and 250 volts supply to them at a total of (approx) 1 amp heater supply.
Thats pretty simple and a light load for a mains transformer ,any thing else like the soft start is after the power supply or additional to it .
Is the soft start faulty or disconnected ?
Thats the only part that might need a circuit diagram as there isn't a standard one unless you buy a module on eBay etc.
Both correct actually.
Duncan has posted the max capability of the EZ90.
The Minimax requires 180-0-180 at around 20/30 mA though it will only consume around 6mA for the two '83's.
The problem is in the filament supply for the EZ90. In their infinite wisdom the transformer winding for the filament uses the same fine gauge wire as the HT winding, and has consequently burnt out. I expect this to happen on all of these preamps so be warned.
What's worse is that when it burns out it can then short onto the mains primary and then blows the leakage trip on your mains supply.
If you don't have an earth leakage trip then this could result in a fire. Hmm, very poor design.
Duncan has posted the max capability of the EZ90.
The Minimax requires 180-0-180 at around 20/30 mA though it will only consume around 6mA for the two '83's.
The problem is in the filament supply for the EZ90. In their infinite wisdom the transformer winding for the filament uses the same fine gauge wire as the HT winding, and has consequently burnt out. I expect this to happen on all of these preamps so be warned.
What's worse is that when it burns out it can then short onto the mains primary and then blows the leakage trip on your mains supply.
If you don't have an earth leakage trip then this could result in a fire. Hmm, very poor design.
Gibodavid I like your manners but are you quoting from the schematic ?
If so no problem but the EZ90 in Wireless Word valve data book says-
input volts (RMS ) = 325-0-325 volts and that applies to the 6X4 as well.
Thats Brimar. UK and probably better it applies to Mullard as well.
I have Linux and all I do if transferring an image from a webpage to a post is to-
Select all -hold and transfer .
If so no problem but the EZ90 in Wireless Word valve data book says-
input volts (RMS ) = 325-0-325 volts and that applies to the 6X4 as well.
Thats Brimar. UK and probably better it applies to Mullard as well.
I have Linux and all I do if transferring an image from a webpage to a post is to-
Select all -hold and transfer .
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JPEG is a poor (fuzzy) choice for line-drawings.
Attachments
Thanks Duncan2. It seems, though, that at some point GilboDavid had a schematic but couldn't upload it. My EE MM is working fine, btw, but just wanted to have a schematic in case things change. Maybe anyone capable of working on it in the future could see what's what w/o a schematic. Mine is the later model with the four inputs (cd, tuner, aux 1 & aux 1) so she's probably got more mileage left in her.
Specifications
Tube Compliment: one 6X4 and two 12AU7
Frequency Response: 10Hz to 150kHz
THD : 0.015%
Output : 2 Volts
S/N Ratio: 93dB
Input Impedance: 100 kOhm
Output Impedance: 1.5 kOhm
Total Gain : 20dB
Power Consumption: 13W
Price: $1,195
https://www.enjoythemusic.com/magazine/equipment/0503/easternelectric.htm
Has a decent amount of gain, but not enough volts to drive an F4.
Tube Compliment: one 6X4 and two 12AU7
Frequency Response: 10Hz to 150kHz
THD : 0.015%
Output : 2 Volts
S/N Ratio: 93dB
Input Impedance: 100 kOhm
Output Impedance: 1.5 kOhm
Total Gain : 20dB
Power Consumption: 13W
Price: $1,195
https://www.enjoythemusic.com/magazine/equipment/0503/easternelectric.htm
Has a decent amount of gain, but not enough volts to drive an F4.