crossfire vr4000

Perry Babin · 2012-02-08 3:26 am

I think I'd try two 9v Zeners if they're connected like the ones I mentioned earlier.

timwebb · 2012-02-08 3:28 am

ok. im ordering them. in a day or two.

Perry Babin · 2012-02-08 3:43 am

Be aware that if those are not close enough to the originals or are being used in a different way, it may blow the output transistors.

timwebb · 2012-02-08 3:52 am

are the diodes are used to stabilize the output drivers? would it be a way to buffer it. if there were a spike in the voltage?

Perry Babin · 2012-02-08 5:54 am

I think they're there to limit the voltage reaching the gates of the FETs. It's just a guess. I rarely see the DLM based amps and have never seen the driver board that you have. You may be able to confirm that that's how they're connected if one end of the two diodes connects to the source leg of the FETs and the other end of the two diodes connects to the gate resistors.

timwebb · 2012-02-18 9:22 pm

i cant find the 1N4237 diode.

Perry Babin · 2012-02-19 5:42 am

Why do you need that diode?

Are you sure that that's the right number?

timwebb · 2012-02-19 5:54 am

i was buying a few of each for testing

Perry Babin · 2012-02-19 6:06 am

Where did you get that number from?

timwebb · 2012-02-19 6:25 am

Perry Babin said:
That's not true for most MELF diodes. Most have no indication as to their rated voltage. In some of the other DLM boards, they used a 1N4237 and a 1N4740 connected in reverse series configuration. I'd suspect that these are similar. You would need at least one good pair to test to know what they really are if you can't get that information from the manufacturer.

i were going to order these for tests.

Perry Babin · 2012-02-19 8:17 am

1N4737 Sorry about that. If something doesn't seem right, ask. I don't have much time to spend here and can't or don't take the time to proofread everything.

timwebb · 2012-02-19 5:17 pm

oh ok.

timwebb · 2012-02-28 5:01 am

got the parts ordered. im reading the board tracing everything. the diodes connects to the other driver card. one end goes to the pin labeled 70v+ and the other end 70v-. i would need 70 volt zener diodes correct?

Perry Babin · 2012-02-28 12:53 pm

For each pair of the two adjacent diodes with the striped ends connected, are you finding that one end is connected to +70v and the other end to -70v?

That doesn't seem right.

timwebb · 2012-02-28 4:38 pm

Yrs. I will check again when I'm off work. But the traces on the board run to each 70+ and 70- on the driver cards.

timwebb · 2012-02-28 7:25 pm

ok checking again the diodes are in parallel. one end of the cathode is on the 70v pin,the other goes to the output transistors one set goes to the irfp240. the other goes to the9240 output gate resistors.

Perry Babin · 2012-02-29 1:37 am

For the two adjacent diodes, are the anodes directly connected?

Are the cathodes directly connected?

timwebb · 2012-02-29 1:59 am

the anodes directly connected. the cathodes are not.

Perry Babin · 2012-02-29 2:00 am

That's not in parallel. They are in series.

timwebb · 2012-02-29 2:07 am

oh my mistake doing to much at one time..

crossfire vr4000

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