Aha....here it is ....to prevent triac latching and fuse blowing........but it is from PT2400/1800 service manual. They recommend adding some resistors ,,to weight,, low line voltage....it should prevent to happen what happens if line voltage drops....so here is my thinking. Maybe you have poor power capability at your outlet. So what happens. voltage drops and amplifier starts to open triac more and more. Lower is the line voltage more is triac open. And this cause very high currents to flow into amp. Psu become somehow resistive load. As you find out this transformer can't be couplet directly to mains. Maybe. On my experience these amps draw very high current spikes when play loud. At poor pwr lines you can observe how lights flicker all around. Maybe everything just work fine. Try some other heavy duty socket. Or at least measure line voltage. I heard story how sensitive are these amps when line voltage drops. It looks like that I have just luck so far. I know a lot of cases when people drive PA hard and then suddenly fries psu from FOH mixer. Why? Voltage drops, magnetic field in transformer falls and primary starts to behave resistive which means heat....Carver amp fight with low lines on it's own manner but only to certain value.....maybe just thinking.
Aha and there is only one more thing.
From PM1.5A/PM1200 service manual..
Driving the output level to maximum at high frequencies with no load can cause the outputs to fail if this condition is sustained. At location R86 change value from a 43E to a 27E.
Maybe something there starts to latch........arround Q23
Best regards
Taj
Aha and there is only one more thing.
From PM1.5A/PM1200 service manual..
Driving the output level to maximum at high frequencies with no load can cause the outputs to fail if this condition is sustained. At location R86 change value from a 43E to a 27E.
Maybe something there starts to latch........arround Q23
Best regards
Taj
Hello Tajzmaj,
thanks for you investgations.
Normally i connect al items via a 4KVA safetytransformer to mains. The Carvers had some problems with starting up. This moment I use a very stable mainsoutlet. In Holland the mains network is very reliable. Mains fluctuations are within 2%. Powercord is only two metres and about 2,5 mm2. No problem for any amplifier.
I know that current increases when linvoltage decreases, as any switched powersupply do.
I checked triac circuit with a scope and no latching occur. Every half period, the triac is tarted again.
Latchup of the poweramp due to HF does not occur.
I hope someone has a good method for testing the magcoil outside the amp.
Speakertech
thanks for you investgations.
Normally i connect al items via a 4KVA safetytransformer to mains. The Carvers had some problems with starting up. This moment I use a very stable mainsoutlet. In Holland the mains network is very reliable. Mains fluctuations are within 2%. Powercord is only two metres and about 2,5 mm2. No problem for any amplifier.
I know that current increases when linvoltage decreases, as any switched powersupply do.
I checked triac circuit with a scope and no latching occur. Every half period, the triac is tarted again.
Latchup of the poweramp due to HF does not occur.
I hope someone has a good method for testing the magcoil outside the amp.
Speakertech
About magcoil....it is just transformer like many others. When i bought my M400 ,,the cube,, have a problem. It was made for American market and it has only 110V primary. I made revers engineering and find nothing special.Connect it via variac, increase voltage till some saturation shows up and connect some sort of load on secondary. You should get only minor difference IN/OUT if you calculate power....nut I'm sure that you know such methods......but as I mentioned before. It is just transformer. I opened one. Smaller but it is still ,,magnetic coil,, From transformer of size like some 100W amp easy deliver 2x200W+ at 8E load.......Here is power nice and stable too. Ljubljana is capital city here and we have here more likely 235VAC but still. We use here German standard(schuko) and 2.5 sq mm wires are installed by law for all domestic outlets and my house has 70 sq mm income cable. By ground....but still. It is worth to measure.
"I'm almost certain that I noticed somewhere in those manuals to do something to prevent fuse blowing at high levels."
I remember a mod to limit the maximum conduction angle. Without this limit, low line voltage (and high amplifier drive levels) will cause the conduction angle to increase to the point where the transformer will overheat ( I saw some that had started smoking).
Yes, it may look like an ordinary transformer, but it will not take a full sine conduction.
I remember a mod to limit the maximum conduction angle. Without this limit, low line voltage (and high amplifier drive levels) will cause the conduction angle to increase to the point where the transformer will overheat ( I saw some that had started smoking).
Yes, it may look like an ordinary transformer, but it will not take a full sine conduction.
Not sure why the mystique about these power supplies survives to this day. It is indeed a transformer similar to any other, the only difference is the primary has reduced turns so that under full load and sagging line it can still provide tight regulation (short term) with the conduction angle control.
You can easily make it smoke however, because it is really only about a 3-400 watt transformer, determined by the line frequency and core volume. Low line and high power causes problems as well, even if no more than a few hundred throughput watts is drawn from the line. It's not because of the increased conduction angle necessarily, but the high peak currents in the relatively light gauge primary winding.
Driving a 1200 watt continuous output (max amplifier rating), will make these transformers blow smoke under any other conditions. I've had my fun with that.
Working high voltage rail in these amps is +-125, IIRC.
You can easily make it smoke however, because it is really only about a 3-400 watt transformer, determined by the line frequency and core volume. Low line and high power causes problems as well, even if no more than a few hundred throughput watts is drawn from the line. It's not because of the increased conduction angle necessarily, but the high peak currents in the relatively light gauge primary winding.
Driving a 1200 watt continuous output (max amplifier rating), will make these transformers blow smoke under any other conditions. I've had my fun with that.
Working high voltage rail in these amps is +-125, IIRC.
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Of course it don't take full sine wave conduction at full voltage(110 or 220vac). But will work just fine if you connect it via variac and turn up the voltage and observe primary current. I think that saturation at m400 shows up at some 50vac for 110v unit. PM1.5 is different amp but the same principal. Uf and don't ask how much work I spend to modify regulator board at m400 which is early version and I was unable to find voltage modification procedure + transformer has only 110V primary.....grrrrr
Hm...I once again look over these manuals and only thing which I can find is from M400 manual where 1 resistor should be replaced if value is different.......and this should reduce max triac firing angle......it is in position R4 according to PM1.5 service manual...which should be 33K 1W for 230V version.
Ha ha ha and here is something from PT1800/2400 service manual.....
,,To prevent fuse from blowing prematurely when driving a 2 ohm load........,, Replace 6.3A fuse with 8A.....ha ha
Good solution....i like such solutions. Very funny. It rocks.
Best regards
Ha ha ha and here is something from PT1800/2400 service manual.....
,,To prevent fuse from blowing prematurely when driving a 2 ohm load........,, Replace 6.3A fuse with 8A.....ha ha
Good solution....i like such solutions. Very funny. It rocks.
Best regards
It is in the manual of PM1.5 written down. Voltageconversion is possible with a splt primary, connected the windings in parrallel or series. If there's only one winding, you'll have to replace the transformer.
R4 is 33 K ohm in my amps. They're factory built for 230 volt operation.
A 6,25 A fuse blows, but a 15A fuse keeps the amp going. But that;s not my style of repairing amps.
I'm afraid that this problem is unsolvable for me.
I tested everything which could lead to those heavy currents, I replaced the transformer for another one and borrowed another amp for comparing electronics and it has the same problem.........
In Holland nobody knows, I mailed anatech, but didn't get response yet.
Who knows.....
Speakertech
R4 is 33 K ohm in my amps. They're factory built for 230 volt operation.
A 6,25 A fuse blows, but a 15A fuse keeps the amp going. But that;s not my style of repairing amps.
I'm afraid that this problem is unsolvable for me.
I tested everything which could lead to those heavy currents, I replaced the transformer for another one and borrowed another amp for comparing electronics and it has the same problem.........
In Holland nobody knows, I mailed anatech, but didn't get response yet.
Who knows.....
Speakertech
I have had to run out with replacement amplifiers to jobs at sites than had inadequate power wiring. Even an extension cord is enough to make a Carver blow fuses.
Amplifiers with 'trick' power supplies (including switch-mode types) don't like inadequate wiring.
I always keep some old style amplifiers (big and heavy) around with beer-can sized filter caps and huge transformers for this very purpose.
Amplifiers with 'trick' power supplies (including switch-mode types) don't like inadequate wiring.
I always keep some old style amplifiers (big and heavy) around with beer-can sized filter caps and huge transformers for this very purpose.
What do you want?
My walloutlet is a 3-phase 230/400 Vac 32amps outlet..When I connect a load of about 20KVA, mainsvoltage drops about 2 volts on each phase. That's less than 1%.
The powercord of the amp is a fat one, 3x 2,5 sq mm and no longer than about 3 feet. Europe has 230 volts, resulting in current draw that's only 50% compared on a 127 net.
I have no doubt about electric power in my lab!
Wherever do you have a better power supply?
I can't get better.
If it is true what you say, no amplifier should operate well.
I assure you, wiring is perfect, mains is also perfect, the problem is in the amp.
Those amps are running since the eighties. I cannot imagine that they alway failed, as there was used an extensioncord or the electric powerstation was not within 100 metres.
This discussion is no use!
Speakertech
Ej Speakertech
I have as before mentioned several of these amps. They work perfectly. I drive them hard even sometimes on bad electricity.....i have no such problems. But what about this idea. Connect some heavy load just on bare psu. Some big 1000W bulb or 3x500W halogen reflector. There you have nice 250vdc supply in the amp. You will find out if there defective psu or something else......
Or sell the amp to me....He he he
Best regards
I have as before mentioned several of these amps. They work perfectly. I drive them hard even sometimes on bad electricity.....i have no such problems. But what about this idea. Connect some heavy load just on bare psu. Some big 1000W bulb or 3x500W halogen reflector. There you have nice 250vdc supply in the amp. You will find out if there defective psu or something else......
Or sell the amp to me....He he he
Best regards
"This discussion is no use!"
I agree, you have no knowledge of the challenge people setting up portable sound systems face.
You have probably never had to face hooking your 120A power distro to a box fed from an 8ga drop from the utility pole.
You have probably never had to call the utility on a Saturday night to replace the transformer on the pole with several thousand people waiting on you.
You have probably never had to put out a grass fire from a temporary power generator while waiting for the utility company to show up (fortunately I had people detailed to watch for this very thing).
etc.
On the other hand, it sounds like there is something wrong with your amplifier. I have never tried to verify how much power my PM1.5 drew while bench testing. I can tell you that it would trip a 20A thermal breaker with both channels driven before reaching the rated 600W/4Ω.
I ended up dumping all my Carver and Soundcraftsman with the PCR power supplies, and a friend dumped all his QSC with switchmode supplies. They all sounded anemic with less than ideal line quality.
I agree, you have no knowledge of the challenge people setting up portable sound systems face.
You have probably never had to face hooking your 120A power distro to a box fed from an 8ga drop from the utility pole.
You have probably never had to call the utility on a Saturday night to replace the transformer on the pole with several thousand people waiting on you.
You have probably never had to put out a grass fire from a temporary power generator while waiting for the utility company to show up (fortunately I had people detailed to watch for this very thing).
etc.
On the other hand, it sounds like there is something wrong with your amplifier. I have never tried to verify how much power my PM1.5 drew while bench testing. I can tell you that it would trip a 20A thermal breaker with both channels driven before reaching the rated 600W/4Ω.
I ended up dumping all my Carver and Soundcraftsman with the PCR power supplies, and a friend dumped all his QSC with switchmode supplies. They all sounded anemic with less than ideal line quality.
Uf sorry Speakertech but just one more joke......
Maybe you have too good power for this amp which is designed for touring where is very often to have ,,loose,, power lines.
Mmmm i like hot extension cords. Once 3x125A connector melts into ice when we worked in a hockey venue.....he he
I really wish that you will repair that amp.
Maybe you have too good power for this amp which is designed for touring where is very often to have ,,loose,, power lines.
Mmmm i like hot extension cords. Once 3x125A connector melts into ice when we worked in a hockey venue.....he he
I really wish that you will repair that amp.
In this case, I'm testing the amp under ideal conditions. Then it should work properly... or not?
The tripping 20A thermal breaker, was that with music or a sinewave input?
Slow blow fuses tripped earlier with a sinewave, but continuous sinewaves are normally spoken not audiosignals in practice.
Speakertech
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My amplifier worked perfectly (as far as I could tell), I was just bench testing it with a sinewave. It drove music just fine, but would trip a breaker if you tried to test it.
The power cord incident was at a high school dance. The students were using their home stereo speakers (two pair of JBL L-100s) and were concerned about blowing up their hi-fi amplifiers, so I loaned them a PA amplifier. The extension cord was probably 16ga and maybe 10~12 foot long. After blowing the fuse we ended up moving the equipment, eliminating the cord, and then the rest of the night was OK.
The power cord incident was at a high school dance. The students were using their home stereo speakers (two pair of JBL L-100s) and were concerned about blowing up their hi-fi amplifiers, so I loaned them a PA amplifier. The extension cord was probably 16ga and maybe 10~12 foot long. After blowing the fuse we ended up moving the equipment, eliminating the cord, and then the rest of the night was OK.
According to service manual it should be 6A slo- blo. But if I'm honest maybe I just leave original fuses in units which I get from USA. If you want I can check what's inside........I also have several units bought in europe but who knows what was replaced. I never care much about exact values but always like to install somehow higher values.....because I think that if something goes wrong will 10A fuse do the job just good.....and I hate fuse blowing at live gigs......