hello!
Now I get -38,4V and +36,6V left and right +36,5V and -38,1V
Its getting closer! But it did not give me an answer!
Teake.
Now I get -38,4V and +36,6V left and right +36,5V and -38,1V
Its getting closer! But it did not give me an answer!
Teake.
Hi Harry
I measured on one monochannel on the + of the elco to gnd, and from - to gnd, I did the same with the other channel. I measured with an multimeter on 200DC. Teake
I measured on one monochannel on the + of the elco to gnd, and from - to gnd, I did the same with the other channel. I measured with an multimeter on 200DC. Teake
Hi Teake,
How did you connect ground to zero?
I would disconnect the Elco (at least the plus side) and do the measurements I described. It can be one of the diodes in the rectifier is blown. That has happened to me.
Greetings, Harry
How did you connect ground to zero?
I would disconnect the Elco (at least the plus side) and do the measurements I described. It can be one of the diodes in the rectifier is blown. That has happened to me.
Greetings, Harry
I connected ground to zero to floating point gnd and now it looks that I'm getting the same figures. It looks like its getting stable now. I'm getting now from one channel +and- 37,1V and from the other 37,2V. For several ours. Thanks Harry.
ps But mayby the rectifiers er broken because I made some shortening in the beginning. I guy in the local elektronics shop told me that that doesn't matter. But you never know! I will measure that.
ps But mayby the rectifiers er broken because I made some shortening in the beginning. I guy in the local elektronics shop told me that that doesn't matter. But you never know! I will measure that.
He Harry I measured the rectifiers + and - to GND and measured the same voltages 24,2V on both rectifiers the same, so I don"t think they are wrong. The PSU looks stable now, so I will connect the pcb's and see what,s happening, and measure that.
Greetings teake.
Greetings teake.
Hi there!
I mounted the pcb's to the psu, there are only 3 of them getting hot. I figured out that I had to put a 221K instead of a 221R on R17 on Cristijan's PCB. When I did that and connected te pcb's there was some smoke coming from one mosfet. At that moment I did not have connected the mosfets to the heatsinks, i turned the power down and cennected them to the heatsinks and put them on the psu again, but only three are getting hot, so what's happening here? Distroyed the mosfets? How can I measure that. Thanks Teake.
I mounted the pcb's to the psu, there are only 3 of them getting hot. I figured out that I had to put a 221K instead of a 221R on R17 on Cristijan's PCB. When I did that and connected te pcb's there was some smoke coming from one mosfet. At that moment I did not have connected the mosfets to the heatsinks, i turned the power down and cennected them to the heatsinks and put them on the psu again, but only three are getting hot, so what's happening here? Distroyed the mosfets? How can I measure that. Thanks Teake.
A smoking mosfet? Just take it out and put a new one in.
In case you don't have a variac try adding a lightbulb (60-100W) in series with the mains wire to prevent high current running through the amp. Turn the bias pots down as well for the time being. I'm in a hurry and will provide a decent link to test transistors when I get back.
/Hugo 🙂
In case you don't have a variac try adding a lightbulb (60-100W) in series with the mains wire to prevent high current running through the amp. Turn the bias pots down as well for the time being. I'm in a hurry and will provide a decent link to test transistors when I get back.
/Hugo 🙂
Uh, now my 3 mosfets who went hot also cooled down and there is no temperture anymore. On the speaker terminals i got 28 and 24 V so what's going on! I am thinking of letting the projekt down, or will let the job done by a professional. But I'm not that kind of guy, I want to win! And listen! Music man, that's my life!
Well I measured the mosfets but than I burned an 221R resister and mayby some other resisters too!, and a part of the pcb maybe. Well I"ll see tomorrow if he will start again.
Hi there!
Well, I did put a new resistor 221R in the pcb and connected the power cable and again the resister began to smoke, what's the problem I'm getting a little confused, what did I wrong.
Teake.
Well, I did put a new resistor 221R in the pcb and connected the power cable and again the resister began to smoke, what's the problem I'm getting a little confused, what did I wrong.
Teake.
Again!
Instead of 221K I had 221 R on the pcb, what can happen with the other parts when I connect them to the main.
Instead of 221K I had 221 R on the pcb, what can happen with the other parts when I connect them to the main.
As there are many 221R resistors in an Aleph it would be nice to know which one went up in smoke.
You can safely assume that, if it's a gate resistor, the mosfet went to heaven. From your previous posts I would expect a fairly high damage rating on a number of semiconductors. Best way to proceed is a thorough check of all mosfets, source resistors and no, there are no 220k R's in your Aleph. 🙂
/Hugo
You can safely assume that, if it's a gate resistor, the mosfet went to heaven. From your previous posts I would expect a fairly high damage rating on a number of semiconductors. Best way to proceed is a thorough check of all mosfets, source resistors and no, there are no 220k R's in your Aleph. 🙂
/Hugo
Please check the original service schematics from Mr. Pass, they give a lot of data about the voltages some parts should generate. It's too late now, but you can check a lot of other areas of your board.
The only 221K resistor present on the original schematics are R19.
Following the data from Mr. Pass in the service manual, this resistor trims the DC current value for the network that regulates the bias. If you used a value 100 times to low, this means you set bias way too high. So you will probably have blown your mosfets. For sure if you tested without the heatsinks mounted.
BTW, you can buy matched mos-fets in Holland. (Not from me). I don't want to advertise for other people, so if you cannot match mosfets yourself give me a pm.
Greetings, Harry
The only 221K resistor present on the original schematics are R19.
Following the data from Mr. Pass in the service manual, this resistor trims the DC current value for the network that regulates the bias. If you used a value 100 times to low, this means you set bias way too high. So you will probably have blown your mosfets. For sure if you tested without the heatsinks mounted.
BTW, you can buy matched mos-fets in Holland. (Not from me). I don't want to advertise for other people, so if you cannot match mosfets yourself give me a pm.
Greetings, Harry
Hi there!
Another question!
Is it possible that, when the mosfets are destroyed, the IRF9610 also been destroyed. I checked the whole pcb several times but I could not find any wrong part or soldering. And why only the 221R burned from the second mosfet and not the others, it's for me a question? Will it burn again when I change again the resistor? I checked the solderings several times but could not find any miswiring or connections. I'ts getting a little frustrated, because it should be an low cost projekt.
Greetings teake.
Another question!
Is it possible that, when the mosfets are destroyed, the IRF9610 also been destroyed. I checked the whole pcb several times but I could not find any wrong part or soldering. And why only the 221R burned from the second mosfet and not the others, it's for me a question? Will it burn again when I change again the resistor? I checked the solderings several times but could not find any miswiring or connections. I'ts getting a little frustrated, because it should be an low cost projekt.
Greetings teake.
Hi Teake,
Mosfets cannot break, except by overheating or a too high gate voltage. As long as you soldered the zeners first, and used your anti-static arm brace while soldering they sould be okay.
Before you put in the new mosfets, check the board without the power mos-fets.
Check that you have +/- 34VDC on the board. (Not there? short circuit!)
Check bias network for the IRF9610. (4-5 VDC)
Your bias network for power mosfets (4-5 VDC)
Try applying signal, and check result on R52.
Now install the power mosfets mounted to a heatsink, and listen to music.
I did not consider the Aleph 5 a lowcost project, but a very high value for money project. Remember to use sufficient heatsinks, or protect on 75 degrees.
Greetings, Harry.
Mosfets cannot break, except by overheating or a too high gate voltage. As long as you soldered the zeners first, and used your anti-static arm brace while soldering they sould be okay.
Before you put in the new mosfets, check the board without the power mos-fets.
Check that you have +/- 34VDC on the board. (Not there? short circuit!)
Check bias network for the IRF9610. (4-5 VDC)
Your bias network for power mosfets (4-5 VDC)
Try applying signal, and check result on R52.
Now install the power mosfets mounted to a heatsink, and listen to music.
I did not consider the Aleph 5 a lowcost project, but a very high value for money project. Remember to use sufficient heatsinks, or protect on 75 degrees.
Greetings, Harry.
- Status
- Not open for further replies.