Sam, used the same method to separate high voltage and low voltage to rails for safety work on GZCA 35K SPL. The best method to work on this type amplifiers. One jumper for HV on PSU, and another for only drive section.
That top mosfet driver (at the beginning) looks like it has a hole in it where the magic smoke escaped! Also, you can use the power supply itself to vary the rail voltage. Just replace one of the resistors in the resistive divider that feeds back to the power supply controller with a pot. As you said, the feedback pin looks for a constant voltage, and once that's achieved, then it stops pumping the power supply essentially. With a pot in the resistive divider, you can change at what rail voltage the feedback pin sees the voltage it wants, and there you have a built in adjustable rail supply! I guess as you mentioned in another comment, that might not give you a huge range on the rail, but it depends on the controller. Some switching controllers can go into pulse skip mode to achieve lower voltages, or when the load (current draw) is really low. They only pulse the boost circuit when the DC rail falls below the target.
That's not correct I'm afraid buddy, the power supply fets are supplied with PWM at all times of course, in order to supply current to the output section. Even with the deadtime set to extremely high, the voltage on the rails is still exactly the same. The only way is with an external rail supply. There is no way to use the original power supply section to vary the rail voltage.
@@barevids What are the part numbers of the mosfet gate driver you removed, and the switching controller where you fool the feedback temporarily? I'd be interested in looking at the datasheets of those... every switching controller I've ever run across sets the output voltage by using a voltage divider to a feedback pin.
i imagine that if the output section is shorted they cook the board with this initial 12v, the firsts taramps "platinium series" had this problem in the past, thanks for the vídeo.
Yo, thanks a TON for your videos, I have learned so much!! I have a question about voltage injection, would it be possible to supply the +/- rails off a battery pack? like +/- 80V directly?
Great great video. Laughed so hard at "if there's any ladies watching....definitely not...who the hell...anyway" :D :D :D :D :D Instead of doing this with the donor board for the +rail voltage, another bench power supply can be used to supply 0-100v. No need of big Amps. Additionally You are using the overcurrent protection of it ;)
Yes very true! I would need a supply with a middle point ground reference though. I find that when I have just hung a. Single ended DC supply across - rail to + rail, it often shifts over time due to uneven current draw from both rails. But yes, that is the eventual solution.
Happy new year Sam and good to see you again! What do you think about In Phase amplifier IPA4001D ? I ask because i hear a lots of negative thinking about In Phase
hey man i just picked up a vfl 750.1, it is blown and im currently working on it, has no lights on it, no power or protect, few mosfets were blown at the output section, i took them out and hooked it up to a 12v supply i have, it draws maximum amperage and then after a loud click from the amp it goes down to about 2 amps, still no lights thoe, any idea on where i should go from here?
@barevids I have a power 1000 chrome rf amp. It hasn’t been powered in 15+ years. The PCB is newer than the amp as RF replaced it for the last factory one years ago. What’s the best way to power it up or test it? I’m uk based so it could go to you? It was working fine last time it was used. Cheers 🤘🏻😀
@@barevids How would I go about that? I haven't powered it up in years and someone did a poor soldering job on the fuse at some point. I would love to know how much you charge for a once over. I'd like to know if it is healthy before installing it. It might be a good idea to recap it. I'm certainly not confident, and I respect you and your knowledge and you sharing it.
That's exactly what I've done here haha. Remember bench supply is DC. Transformer needs AC. So we use switching supply of a spare amp tand it's transformers to step up voltage.
I have a sundown sfb 3000 it's I guess China Brazilian board the speaker outputs for the sub is putting out DC voltage I don't know what I should replace on the amp I don't know if my repair guy in my city knows how to fix these kind of amps
@@barevids no I mean the app was working good for a while and now it's not when I hook up a sub to the speaker I'll put the sub pushes all the way out and stays that way
It would be cool to see you tidy that up into a stand alone high voltage dc power supply with its own voltage and current display. I think it could be done for pretty inexpensively, maybe even mount the high voltage portion of the power supply remotely so it doesn’t take up so much workspace.
