Hi all,
Working on my RF T1500, seems to be an issue with the power supply card, I'm not seeing any gate drive. I've removed the card but haven't started measuring stuff yet but will start on that tomorrow. What typically goes out on these?
Does anyone have the schematic for this power board (1325-52873-06)? I have the schematic of a T1000BD that I'm referencing off of.
Also, is there a direct replacement for the LM339DG comparators? They seem to be obsolete.
Thanks
edit: after browsing around on here i've found out about quest components which have the LM339DG in stock 🙂
Working on my RF T1500, seems to be an issue with the power supply card, I'm not seeing any gate drive. I've removed the card but haven't started measuring stuff yet but will start on that tomorrow. What typically goes out on these?
Does anyone have the schematic for this power board (1325-52873-06)? I have the schematic of a T1000BD that I'm referencing off of.
Also, is there a direct replacement for the LM339DG comparators? They seem to be obsolete.
Thanks
edit: after browsing around on here i've found out about quest components which have the LM339DG in stock 🙂
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Try Rockford to see if they've released the diagram you need.
Any LM339 in the SOIC package should work. One example:
LM339DRG4 - Octopart
Any LM339 in the SOIC package should work. One example:
LM339DRG4 - Octopart
Thanks Perry, I saw some variances in the specs and wasn't sure about it, but that's good to know!
Also, are these the original fets on the power supply section?
I came across a thread earlier that mentioned they were IRFP parts.
Output FETs:
Also, are these the original fets on the power supply section?
An externally hosted image should be here but it was not working when we last tested it.
I came across a thread earlier that mentioned they were IRFP parts.
Output FETs:
An externally hosted image should be here but it was not working when we last tested it.
You can generally look at the solder connections to determine if they're original.
The HUF75344 (in photo) are the originals. Many people use the IRFP064N as replacements.
The HUF75344 (in photo) are the originals. Many people use the IRFP064N as replacements.
Spent some time working on it today. There is no output drive from the UC3526 IC. Inputs to +E and -E are 5V and 0V respectively (on UC3526), which makes sense since I only have power into GND and REMOTE of the amp. Shutdown,reset,vRef signals are 5V as well. Supply voltages look normal as well, 12v. So asides from no drive output, everything else seems OK, but I know this doesn't mean the IC itself is good.
Next, I took a look at the LM339 ICs. Supply voltages are good on both LM339s. Then I checked the output of each comparator within that package and they are all 5V, except for output #4 on U101. Should all outputs be logic HIGH or LOW for normal operation?
Next, I took a look at the LM339 ICs. Supply voltages are good on both LM339s. Then I checked the output of each comparator within that package and they are all 5V, except for output #4 on U101. Should all outputs be logic HIGH or LOW for normal operation?
UC3526:
pin 12 - 0v
pin 11 - 0v
pin 10 - ~4V
pin 9 - ~3V
Shouldn't there supposed to be something into sync? What drives this?
pin 12 - 0v
pin 11 - 0v
pin 10 - ~4V
pin 9 - ~3V
Shouldn't there supposed to be something into sync? What drives this?
Hi Perry,
Pin 14 - about 12v
Pin 17 - about 12v
Pin 18 - 5v
I noticed the IC with markings AH-16, all the pins do not measure anything. What is this IC? It looks like a voltage regulator, but it doesn't seem to be?
Pin 14 - about 12v
Pin 17 - about 12v
Pin 18 - 5v
I noticed the IC with markings AH-16, all the pins do not measure anything. What is this IC? It looks like a voltage regulator, but it doesn't seem to be?
AH-16?
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That's interesting. It seems that AH-16 references BCP53-16, looking at the datasheet it has a lower beta compared to PZTA56.
I wonder if this was changed before? It does seem like someone has worked on this driver board before since I see flux residue and unclean solder connections. Specifically on R104, this is a 20ohm resistor instead of a 10ohm resistor from what I'm seeing online?
What the PZTA56 drive? I should be seeing at least something on the emitter pin?
And yes, I ran out of chipquik and didn't have an extra hand for using two soldering irons. I've the board connected via jumper wires now for testing.
I wonder if this was changed before? It does seem like someone has worked on this driver board before since I see flux residue and unclean solder connections. Specifically on R104, this is a 20ohm resistor instead of a 10ohm resistor from what I'm seeing online?
What the PZTA56 drive? I should be seeing at least something on the emitter pin?
And yes, I ran out of chipquik and didn't have an extra hand for using two soldering irons. I've the board connected via jumper wires now for testing.
Check with Rockford to see if the diagram for this board has been released. I'm assuming that you only have the main board for the 1000 since they use the same PS board.
R104 could be a factory revision. My photos have it as a 10 ohm.
R104 could be a factory revision. My photos have it as a 10 ohm.
The amp was sitting on my bench for a day. Today I went to go work on it and the moment it powered up, I saw gate drive, despite not having done anything new. Applied B+ and the amp turned on fine, no protection, etc.
Then it turned off, gate drive disappears. I thinking loose connection so I start pushing on random components on the driver board and nothing. I flex the driver board a little and it will come and go at certain times. Now I'm thinking cold solder joint somewhere? Reflow all connections and same thing.
I do notice now, that the protect light is on now, before it wasn't, even with no gate drive.
I was about to take down some measurements when gate drive was present and not present.
Gate drive present:
UC3526:
1 - 5V
2 - 12mV
3 - 4.21V
4 - 4.73V
5 - 5V
6 - 9mV
7 - 9mV
8 - 5V
9 - 3.63V
10 - 2.09V
11 - 20mV
12 - (see attached picture for sync, about 1.5V amplitude)
13 - see gate drive picture (measured at fets)
14 - 12V
15 - ground
16 - see gate drive picture (measured at fets)
17 - 12V
18 - 5V
U101 (lm339)
1 - 5V
2 - 6.38V
3 - 12V
4 - 75mV
5 - 2.88V
6 - 2.5V
7 - 6.95V
8 - 4.09V
9 - 4.57V
10 - 0.443V
11 - 5.44V
12 - 4mV
13 - 9mV
14 - 9mV
U102
1 - 6.38V
2 - 6.43V
3 - 12V
4 - 0.35V
5 - 3.0V
6 - 79mV
7 - 2.88V
8 - 3.94V
9 - 5V
10 - 1mV
11 - 7.42V
12 - 9mV
13 - 7.61
14 - 7.61V
No gate drive
UC3526
All pins the same except for shutdown (pin 8) which is now ~0V and sync (pin 12), about 1.1V amplitude and no waveform.
U101
1 - 5V
2 - 1.35V
3 - 12V
4 - 0.388V
5 - 1.6V
6 - 2.5V
7 - 2.26V
8 - 4.09V
9 - 2.84V
10 - 0.457V
11 - 9mV
12 - 9mV
13 - 9mV
14 - 0.64V
U102
1 - 0.73V
2 - 2.1V
3 - 12V
4 - 0.364V
5 - 2.72V
6 - 0.30V
7 - 1.56V
8 - 3.89V
9 - 4.98V
10 - 4.98V
11 - 7.32V
12 - 8mV
13 - 3.09V
14 - 3.09V
Another thing I noticed is, when I first apply power to the amp, I will see gate drive for a second before it goes away (sometimes longer). When it goes away, I can sometimes power cycle and I will see gate drive each time before going away. When I see the gate drive it looks normal as well.
Initially I was thinking a bad driver transistor because of the weird gate drive waveforms that occasionally show up, but since the outputs of the comparators on the LM339 also change, I'm thinking there is a bigger issue as well?
I have replacement ICs coming tomorrow for UC3526 and the LM339s. But they seem to be working?
also: still pending on rockford if they will supply me with the schematics.
Then it turned off, gate drive disappears. I thinking loose connection so I start pushing on random components on the driver board and nothing. I flex the driver board a little and it will come and go at certain times. Now I'm thinking cold solder joint somewhere? Reflow all connections and same thing.
I do notice now, that the protect light is on now, before it wasn't, even with no gate drive.
I was about to take down some measurements when gate drive was present and not present.
Gate drive present:
UC3526:
1 - 5V
2 - 12mV
3 - 4.21V
4 - 4.73V
5 - 5V
6 - 9mV
7 - 9mV
8 - 5V
9 - 3.63V
10 - 2.09V
11 - 20mV
12 - (see attached picture for sync, about 1.5V amplitude)
13 - see gate drive picture (measured at fets)
14 - 12V
15 - ground
16 - see gate drive picture (measured at fets)
17 - 12V
18 - 5V
U101 (lm339)
1 - 5V
2 - 6.38V
3 - 12V
4 - 75mV
5 - 2.88V
6 - 2.5V
7 - 6.95V
8 - 4.09V
9 - 4.57V
10 - 0.443V
11 - 5.44V
12 - 4mV
13 - 9mV
14 - 9mV
U102
1 - 6.38V
2 - 6.43V
3 - 12V
4 - 0.35V
5 - 3.0V
6 - 79mV
7 - 2.88V
8 - 3.94V
9 - 5V
10 - 1mV
11 - 7.42V
12 - 9mV
13 - 7.61
14 - 7.61V
No gate drive
UC3526
All pins the same except for shutdown (pin 8) which is now ~0V and sync (pin 12), about 1.1V amplitude and no waveform.
U101
1 - 5V
2 - 1.35V
3 - 12V
4 - 0.388V
5 - 1.6V
6 - 2.5V
7 - 2.26V
8 - 4.09V
9 - 2.84V
10 - 0.457V
11 - 9mV
12 - 9mV
13 - 9mV
14 - 0.64V
U102
1 - 0.73V
2 - 2.1V
3 - 12V
4 - 0.364V
5 - 2.72V
6 - 0.30V
7 - 1.56V
8 - 3.89V
9 - 4.98V
10 - 4.98V
11 - 7.32V
12 - 8mV
13 - 3.09V
14 - 3.09V
Another thing I noticed is, when I first apply power to the amp, I will see gate drive for a second before it goes away (sometimes longer). When it goes away, I can sometimes power cycle and I will see gate drive each time before going away. When I see the gate drive it looks normal as well.
Initially I was thinking a bad driver transistor because of the weird gate drive waveforms that occasionally show up, but since the outputs of the comparators on the LM339 also change, I'm thinking there is a bigger issue as well?
I have replacement ICs coming tomorrow for UC3526 and the LM339s. But they seem to be working?
also: still pending on rockford if they will supply me with the schematics.
Attachments
Today I replaced UC3526 & both LM339s. Got more consistent gate drive initially. Applied B+ and blue power light came on but the protect light was on was well. It was drawing ~3A @ 13v. Noticed the output FETs getting slightly warm so I disconnected everything and put it back in the case.
Once it was back in the case, when I apply B+ it would attempt to turn on but not fully turn on (rapid pulsing noises). I look at gate drive and I can see spikes (see picture attached).
Now gate drive is gone again and will occasionally come back. Also the protect light will sometimes be on and sometimes off.
I think it is something causing the PWM driver to turn off and its borderline between on & off. What conditions causes the PWM driver to turn off?
Also, what drives SYNC? In the T1000bd schematic, it is driven by a 74HC74A flip flop.
Once it was back in the case, when I apply B+ it would attempt to turn on but not fully turn on (rapid pulsing noises). I look at gate drive and I can see spikes (see picture attached).
Now gate drive is gone again and will occasionally come back. Also the protect light will sometimes be on and sometimes off.
I think it is something causing the PWM driver to turn off and its borderline between on & off. What conditions causes the PWM driver to turn off?
Also, what drives SYNC? In the T1000bd schematic, it is driven by a 74HC74A flip flop.
Attachments
When you have the pulses like those in the image above, what's the DC voltage measured directly across the middle legs of the rectifiers?
What happens to the drive signal if you lower the DC supply voltage to about 11.5v?
What happens to the drive signal if you lower the DC supply voltage to about 11.5v?
pin 2 of the rectifiers i'm seeing +100V and -100V on the two rectifiers.
After not touching the amp for a few hours, I go to turn it on and gate drive is there again. But it is kind of a rounded saw toothed look (see attached). I modulate the input voltage to 11V to 14V and as I'm modulating, I see that the gate drive will jump between this rounded saw tooth waveform to a normal square waveform. After a few seconds of modulating the waveform is a nice square waveform and not switching back and forth.
I connect B+ the amp turns on, has blue power LED and the protect LED is slightly on (very dim). I connect a speaker and touch the RCAs input and the speaker moves.. So amp is working, when it does work.
After about 30 seconds of the amp being powered on, i hear switching noises coming from the power supply section. I look at gate drive and it is still a nice square waveform but it is shifting around a bit, looks like the frequency is unstable. I noticed that the switching freq with just GND and remote power is about 36kHz and when B+ is applied it drops to about 26kHz. I guess this is how they change duty cycle since the pulse width remains the same but freq decreases, effectively increasing the duty cycle.
edit: sorry for the sideways pics... it looks fine on the computer before uploading
edit2: also, i measured the rectifier voltages with my scope so that is peak voltage, and not the averaged voltage.. maybe around 70V averaged voltage on pin 2 of the rectifiers?
After not touching the amp for a few hours, I go to turn it on and gate drive is there again. But it is kind of a rounded saw toothed look (see attached). I modulate the input voltage to 11V to 14V and as I'm modulating, I see that the gate drive will jump between this rounded saw tooth waveform to a normal square waveform. After a few seconds of modulating the waveform is a nice square waveform and not switching back and forth.
I connect B+ the amp turns on, has blue power LED and the protect LED is slightly on (very dim). I connect a speaker and touch the RCAs input and the speaker moves.. So amp is working, when it does work.
After about 30 seconds of the amp being powered on, i hear switching noises coming from the power supply section. I look at gate drive and it is still a nice square waveform but it is shifting around a bit, looks like the frequency is unstable. I noticed that the switching freq with just GND and remote power is about 36kHz and when B+ is applied it drops to about 26kHz. I guess this is how they change duty cycle since the pulse width remains the same but freq decreases, effectively increasing the duty cycle.
edit: sorry for the sideways pics... it looks fine on the computer before uploading
edit2: also, i measured the rectifier voltages with my scope so that is peak voltage, and not the averaged voltage.. maybe around 70V averaged voltage on pin 2 of the rectifiers?
Attachments
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One of the protection LEDs will remain partly lit. That's normal.
You have to measure rail voltage with both probes on the rectifiers' center legs, neither probe on ground.
The frequency of oscillation for the PS will read differently after the output stage begins to oscillate and the two oscillators are synchronized.
You have to measure rail voltage with both probes on the rectifiers' center legs, neither probe on ground.
The frequency of oscillation for the PS will read differently after the output stage begins to oscillate and the two oscillators are synchronized.
So Rockford will not provide the schematics.
It is at a point where it will now attempt to turn on every time. I'll hear it try to charge up the caps for a second and then it will go into protect.
Sometimes, it will turn on and stay on. When it does stay on, eventually it will start producing switching noises and the gate drive looks like its oscillating, but the amp stays on and will continue to play music.
When the amp is on, measuring the rectifier center leg with a regular multimeter, one lead on ground, i'm seeing 43.4V and -49V. HV test point jumper is showing ~93V. I wasn't sure what you meant by leaving out the probe ground since my PSU is earthed to the same point as my scope.
Any ideas what typically causes it to try and turn on but then go into protect?
edit: going to try and replace the TL072C op amp.
It is at a point where it will now attempt to turn on every time. I'll hear it try to charge up the caps for a second and then it will go into protect.
Sometimes, it will turn on and stay on. When it does stay on, eventually it will start producing switching noises and the gate drive looks like its oscillating, but the amp stays on and will continue to play music.
When the amp is on, measuring the rectifier center leg with a regular multimeter, one lead on ground, i'm seeing 43.4V and -49V. HV test point jumper is showing ~93V. I wasn't sure what you meant by leaving out the probe ground since my PSU is earthed to the same point as my scope.
Any ideas what typically causes it to try and turn on but then go into protect?
edit: going to try and replace the TL072C op amp.
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