Hello !
I have a car amp whose scheme I can't find Ground Zero GZIA 2230 HPX but we can talk about a similar scheme - gzha-2350x.
This amplifier I suspect has a short or poor insulation in the power supply transformer because it has a very high idle current (6A).
FPQ 50N60 were tested, they had 1.5 V on low - direct polarization, I exchanged them with new ones, as well, high consumption without any load. The load is due to the low insulation of the source transformer.
The amplifier works perfectly fed separately differentially directly on capacitors.
Rectifier diodes are ok. With them removed, there is still a huge idle current consumed by the switching source. FPQ 50N60 is constantly incing.
On electrolytes there is a rectified voltage (the amplifier is powered by 2x12V / 50W in parallel which lights up 75% - so 75 W, so it would be a current of about 6A) but if it is supplied at 12 V directly, the transformer heats up and emits smoke.
I see no other load except the transformer which has a few turns on each winding.
In the primary it has 0.6 ohms.
In the secondary it has 0.2 ohms.
I am interested in who has the expertise on these transformers if the resistors are ok at 0.2 and 0.6 ohm.
It probably needs to be rewound.
I see no other explanation for such a big idle current with impeccable final stage.
Thanks
I have a car amp whose scheme I can't find Ground Zero GZIA 2230 HPX but we can talk about a similar scheme - gzha-2350x.
This amplifier I suspect has a short or poor insulation in the power supply transformer because it has a very high idle current (6A).
FPQ 50N60 were tested, they had 1.5 V on low - direct polarization, I exchanged them with new ones, as well, high consumption without any load. The load is due to the low insulation of the source transformer.
The amplifier works perfectly fed separately differentially directly on capacitors.
Rectifier diodes are ok. With them removed, there is still a huge idle current consumed by the switching source. FPQ 50N60 is constantly incing.
On electrolytes there is a rectified voltage (the amplifier is powered by 2x12V / 50W in parallel which lights up 75% - so 75 W, so it would be a current of about 6A) but if it is supplied at 12 V directly, the transformer heats up and emits smoke.
I see no other load except the transformer which has a few turns on each winding.
In the primary it has 0.6 ohms.
In the secondary it has 0.2 ohms.
I am interested in who has the expertise on these transformers if the resistors are ok at 0.2 and 0.6 ohm.
It probably needs to be rewound.
I see no other explanation for such a big idle current with impeccable final stage.
Thanks
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Shorted transformers (primary-primary or secondary-secondary) generally cause extreme current draw (much more than 6A unless the power supply is limited to 6A).
Are the PS FETs heating up?
Does your amp have two transformers?
How many FETs per transformer?
Are the PS FETs heating up?
Does your amp have two transformers?
How many FETs per transformer?
You have similar diagram posted above, we can talk on it, it is about the same.
Are the PS FETs heating up?- yes, a lot
Does your amp have two transformers? - no, only one core by 4 coils / 4 coils
How many FETs per transformer? - 1 per coil = 4 FETs for the only one transformer
See on diagram "service-ground-zero_gzha-2350x_pre_sch_2"
Are the PS FETs heating up?- yes, a lot
Does your amp have two transformers? - no, only one core by 4 coils / 4 coils
How many FETs per transformer? - 1 per coil = 4 FETs for the only one transformer
See on diagram "service-ground-zero_gzha-2350x_pre_sch_2"
Please post good quality photos of 'your' amp.
The resistance of the coils doesn't mean much unless one is open.
Do you have a scope?
Please (and this applies to anyone who needs repair help) use your sig line to list all equipment you have, editing it as equipment changes. Include the model numbers. If you can't do this due to being a new member, make a list in the next post.
Top of page, menu USER CP >> EDIT SIGNATURE
Oscilloscope (yes or no)
Multimeter(s)
Type of signal source (grounded RCA shields preferred).
Soldering iron
Desoldering pump
Power supply
2 ohm current limiting resistor (hollow cylindrical ceramic 100w preferred)
The resistance of the coils doesn't mean much unless one is open.
Do you have a scope?
Please (and this applies to anyone who needs repair help) use your sig line to list all equipment you have, editing it as equipment changes. Include the model numbers. If you can't do this due to being a new member, make a list in the next post.
Top of page, menu USER CP >> EDIT SIGNATURE
Oscilloscope (yes or no)
Multimeter(s)
Type of signal source (grounded RCA shields preferred).
Soldering iron
Desoldering pump
Power supply
2 ohm current limiting resistor (hollow cylindrical ceramic 100w preferred)
1)it is very hard to read such low ohm values with any precision.
Even shorting plugs and substracting "parasitic"/remaining value is VERY crude.
I suggest you build a 100 mA constant current source, very easy, not even need to build the full supply but an add-on regulator, feed that current to mystery resistor (here a winding) and measure voltage drop in the 200mV scale.
New scale: 2 ohm full scale, so 0.2 ohm=20mV , easy peasy.
2) I suspect that transformer and although rare, you MAY have a shorted secondary: that transformer is step-UP so secondary MUST have higher DCR than primary, even if we are talking sub-ohm levels.
Post close up pictures of YOUR transformer, then remove it, unglue ferrite core parts if needed, count turns, measure wire and rewind it.
Those use very few turns of thick wire, easy to rewind by hand.
The one you linked has 5+5 turn primary, 17+17 turns secondary, for around 45+45V rails.
Yours should not be too different.
Even shorting plugs and substracting "parasitic"/remaining value is VERY crude.
I suggest you build a 100 mA constant current source, very easy, not even need to build the full supply but an add-on regulator, feed that current to mystery resistor (here a winding) and measure voltage drop in the 200mV scale.
New scale: 2 ohm full scale, so 0.2 ohm=20mV , easy peasy.
2) I suspect that transformer and although rare, you MAY have a shorted secondary: that transformer is step-UP so secondary MUST have higher DCR than primary, even if we are talking sub-ohm levels.
Post close up pictures of YOUR transformer, then remove it, unglue ferrite core parts if needed, count turns, measure wire and rewind it.
Those use very few turns of thick wire, easy to rewind by hand.
The one you linked has 5+5 turn primary, 17+17 turns secondary, for around 45+45V rails.
Yours should not be too different.