RF T1500-1BD

brandes.cm · 2nd November 2011, 01:35 PM

The two mylar caps in the output filter circuit are completely toast, would anyone know the value? The only number I have for the pcb is 1325-52759-05. RF support is down and can't ask for a schematic, I would guess they won't release it anyway.

Gate resistor value for the PS fets as well?

I have never seen such a mess before, apparently the guy didn't fuse this amp. The PS fets started on fire and actually cooked the paint on the clamp.

Perry Babin · 2nd November 2011, 01:47 PM

From photos I have, it appears that the output filter caps are 6.8uf. I can't read the voltage. The gate resistors for the power supply are 60.4 ohms.

At least it's repairable. The following amp wasn't.
IrfanView HTML-Thumbnails

brandes.cm · 2nd November 2011, 02:11 PM

Would you have a schematic for anything in that era?
brandes.cm@gmail.com

The current sense resistors Dale WSR .01 ohm, 3W or 5W? They list the same package size for both. The 5W may have the pad on the bottom of the package though.

Perry Babin · 2nd November 2011, 02:15 PM

The ones in the amp photos are marked WSR-3 which are 3w resistors.

Sorry, no schematic. They weren't releasing it when I last inquired.

brandes.cm · 3rd November 2011, 03:41 PM

The caps are 100V, was able read one once it was removed and cleaned.

brandes.cm · 12th November 2011, 02:50 AM

Still having issues with this amp. If I just apply B+ and gnd or Rem and gnd I have no issues. I can see the gate drive signal in the power supply. One side goes from gnd to B+ and the other is referenced above gnd and switches from here to B+. Looks to be a nice square wave at 50% duty cycle.

Should the sync signal be sawtooth 100Khz? I am basing this off the 1000BD schematic I have.

brandes.cm · 12th November 2011, 03:07 AM

Cancel that, I see the sync signal is suppose to be a low pulse just as it's acting.

I pulled the rectifiers and still the same reaction of my supply going into over current mode. Maybe the transformer is garbage?

Perry Babin · 12th November 2011, 03:10 AM

If the drive signal on the gates doesn't go all of the way to ground, the PNP drivers are likely defective.

I've never seen a sawtooth waveform on the sync pin but I rarely check that pin. The frequency will be twice the frequency of the output frequency on pins 13 and 16.

brandes.cm · 12th November 2011, 03:23 AM

I was getting the 100Khz carrier and sync signal mixed up. The sync looks to be generated from a set of Flip-Flops from the carrier signal. It's divided by 2 first then the sync is generated.

I will just pull that board again and replace the drivers.

brandes.cm · 12th November 2011, 04:37 AM

All working now, thanks again.
Bad drivers causing my grief.

2nd November 2011, 01:35 PM	#1
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	RF T1500-1BD The two mylar caps in the output filter circuit are completely toast, would anyone know the value? The only number I have for the pcb is 1325-52759-05. RF support is down and can't ask for a schematic, I would guess they won't release it anyway. Gate resistor value for the PS fets as well? I have never seen such a mess before, apparently the guy didn't fuse this amp. The PS fets started on fire and actually cooked the paint on the clamp.

2nd November 2011, 01:47 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	From photos I have, it appears that the output filter caps are 6.8uf. I can't read the voltage. The gate resistors for the power supply are 60.4 ohms. At least it's repairable. The following amp wasn't. IrfanView HTML-Thumbnails __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

2nd November 2011, 02:15 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The ones in the amp photos are marked WSR-3 which are 3w resistors. Sorry, no schematic. They weren't releasing it when I last inquired. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

12th November 2011, 03:10 AM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If the drive signal on the gates doesn't go all of the way to ground, the PNP drivers are likely defective. I've never seen a sawtooth waveform on the sync pin but I rarely check that pin. The frequency will be twice the frequency of the output frequency on pins 13 and 16. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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2nd November 2011, 02:11 PM	#3
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Would you have a schematic for anything in that era? brandes.cm@gmail.com The current sense resistors Dale WSR .01 ohm, 3W or 5W? They list the same package size for both. The 5W may have the pad on the bottom of the package though.

3rd November 2011, 03:41 PM	#5
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	The caps are 100V, was able read one once it was removed and cleaned.

12th November 2011, 02:50 AM	#6
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Still having issues with this amp. If I just apply B+ and gnd or Rem and gnd I have no issues. I can see the gate drive signal in the power supply. One side goes from gnd to B+ and the other is referenced above gnd and switches from here to B+. Looks to be a nice square wave at 50% duty cycle. Should the sync signal be sawtooth 100Khz? I am basing this off the 1000BD schematic I have.

12th November 2011, 03:07 AM	#7
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	Cancel that, I see the sync signal is suppose to be a low pulse just as it's acting. I pulled the rectifiers and still the same reaction of my supply going into over current mode. Maybe the transformer is garbage?

12th November 2011, 03:23 AM	#9
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	I was getting the 100Khz carrier and sync signal mixed up. The sync looks to be generated from a set of Flip-Flops from the carrier signal. It's divided by 2 first then the sync is generated. I will just pull that board again and replace the drivers.

12th November 2011, 04:37 AM	#10
brandes.cm diyAudio Member Join Date: Sep 2009 Location: Wisconsin	All working now, thanks again. Bad drivers causing my grief.

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