Im working on a fosgate 550x. Ive replaced the power supply fets, checked the gate resistors,and checked all mpsa 56's and 06's. When power and ground are applied NO remote the amp draws 20 amps or more of current. Wondering what do i check next im stummped
Sorry forgot to metion in last post i checked all outputs, the 317's 337's and u1620's and 1620r's all check fine
Connect ONLY remote and ground. With your black meter probe on chassis ground, what is the DC voltage on each of the gate legs of the power supply FETs?
Are all PS FET gate resistors within tolerance?
Are all PS FET gate resistors within tolerance?
All the gates measure 3.82 volts. the other two legs on all power supply fets read 13.91 volts. the gate resistors all read 10.1 ohms
Further checking in this amp it looks like the torriod got hot at one time and melted the coating off one of the leads.
So wondering where do i go from here?
Further checking in this amp it looks like the torriod got hot at one time and melted the coating off one of the leads.
So wondering where do i go from here?
Sorry did that wrong the first time the gates read 10.08 volts.
The other two leads on the fets are 0 volts.
Looks like the torriod got hot at one point it melted the coating off one of the leads.
Wondering where do i go from here
The other two leads on the fets are 0 volts.
Looks like the torriod got hot at one point it melted the coating off one of the leads.
Wondering where do i go from here
If you're reading 10v on the gates, the PNP driver transistors (likely marked 2A) are open. They will be near the TL494.
Is only one turn damaged or do you have multiple turns damaged on the transformer?
Can you post a photo of it?
Is only one turn damaged or do you have multiple turns damaged on the transformer?
Can you post a photo of it?
I can't see enough detail on the transformer.
If only 1 winding (the terminal winding) is shorted, you may be able to desolder it and insulate it with heatshrink tubing or Kapton tape to prevent it from shorting. If there is more significant damage, you will have to get a replacement transformer from Rockford or rewind the one you have.
If you have replacements for the driver transistors, replace them and measure the gate voltage again.
If only 1 winding (the terminal winding) is shorted, you may be able to desolder it and insulate it with heatshrink tubing or Kapton tape to prevent it from shorting. If there is more significant damage, you will have to get a replacement transformer from Rockford or rewind the one you have.
If you have replacements for the driver transistors, replace them and measure the gate voltage again.
i replaced one 2a on the board went to measure the voltage on the gates 1 side theres no voltage at all wondering what the problem might be
What's the DC voltage on pin 9 of the 494?
Pin 10?
The base of the 1a drivers?
The collector of the 1A drivers?
Pin 10?
The base of the 1a drivers?
The collector of the 1A drivers?
i measured the voltage on all the pins of the 494
Pin1-- 0 volts
pin2-- 4.73
pin3-- .06
pin4-- .10
pin5-- 1.53
pin6-- 3.43
pin7-- 0
pin8-- 13.17
pin9-- 5.06
pin10-- 5.67
pin11-- 13.17
pin12-- 13.17
pin13-- 5.02
pin14-- 5.02
pin15-- 5.02
pin16-- 0
all reading are with just remote wire and ground hooked up.
Also on the 1a drivers they are showing no voltage on any of them
Pin1-- 0 volts
pin2-- 4.73
pin3-- .06
pin4-- .10
pin5-- 1.53
pin6-- 3.43
pin7-- 0
pin8-- 13.17
pin9-- 5.06
pin10-- 5.67
pin11-- 13.17
pin12-- 13.17
pin13-- 5.02
pin14-- 5.02
pin15-- 5.02
pin16-- 0
all reading are with just remote wire and ground hooked up.
Also on the 1a drivers they are showing no voltage on any of them
I don't have the schematic diagram for this amp but if it's like virtually every other Rockford amp using the 494, the collector of the 1A driver transistors should be directly connected to pins 11 and 12 of the 494. Find the open trace or feedthrough and repair it.
ok 1 quick question on this amp is it common or do i have something shorted the power supply fets are mtp75n05hd.
the drain and the source of the fets show 0 ohms between them like they are connected together i took them out and touched the pads.
i still get 0 ohms between the drain and source on the pads is this normal or is something shorted?
the drain and the source of the fets show 0 ohms between them like they are connected together i took them out and touched the pads.
i still get 0 ohms between the drain and source on the pads is this normal or is something shorted?
0 ohms isn't normal.
It could be due to a shorted transformer winding. Clamp your meter probes in the B+ and ground terminals (nothing else connected to the amp). With the meter set to diode check or continuity (wherever it beeps when the probes are shorted), twist the transformer. Does the meter go from showing a short to showing something closer to an open circuit?
If not, the windings may be welded together or have too much pressure between them to break the connection between them when twisting the transformer.
If you're absolutely sure that you don't have a short between the pads on the FETs and the FETs are not defective, pull the transformer (or at least the 4 wires on the secondary. If the short is through the transformer, the short between legs 2 and 3 of the FETs should clear.
It could be due to a shorted transformer winding. Clamp your meter probes in the B+ and ground terminals (nothing else connected to the amp). With the meter set to diode check or continuity (wherever it beeps when the probes are shorted), twist the transformer. Does the meter go from showing a short to showing something closer to an open circuit?
If not, the windings may be welded together or have too much pressure between them to break the connection between them when twisting the transformer.
If you're absolutely sure that you don't have a short between the pads on the FETs and the FETs are not defective, pull the transformer (or at least the 4 wires on the secondary. If the short is through the transformer, the short between legs 2 and 3 of the FETs should clear.
thanks perry the transformer is junk . hooked the power and ground probes up to the terminals and it is shorted. turning twisting doesnt help at all the ttransformer is junk.
wondering if this amp is worth fixing ?? or is it a parts amp? any advice would greatly be appericated
wondering if this amp is worth fixing ?? or is it a parts amp? any advice would greatly be appericated
You can rewind the transformer. Do you have a dial or digital caliper?
Before you do that, you should get a good drive signal to the FETs.
Before you do that, you should get a good drive signal to the FETs.
does anyone know of anyone who rewinds transformers??
Gonna be honest with u i dont have the first clue on how to do it
Gonna be honest with u i dont have the first clue on how to do it
All you have to do is...
Measure the wire so you know what gauge to buy.
Buy it from eBay, Amidon, Surplus Sales of Nebraska...
Remove the windings from the core counting the number of windings and paying attention to the way they're laid down on the core. Photographing it from several angles before removing any windings will help you to remember the layout.
Replace the windings with new wire.
If you don't want to rewind it, Check with Rockford. I think most of their transformers are in the $25-30 range.
Measure the wire so you know what gauge to buy.
Buy it from eBay, Amidon, Surplus Sales of Nebraska...
Remove the windings from the core counting the number of windings and paying attention to the way they're laid down on the core. Photographing it from several angles before removing any windings will help you to remember the layout.
Replace the windings with new wire.
If you don't want to rewind it, Check with Rockford. I think most of their transformers are in the $25-30 range.
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