Hello all !
The U1-74ACT00 IC fried while I was testing a new classic board.
All worked great for a few minutes, them, the LCD went dark, there was no power at TX and I saw that the 74ACT00 was getting a lot of hot.
I removed the 74ACT from the board and tested alone with 5v. The IC gets hot a lot. Its fried.
Without 74ACT, the RX works fine.
As Im waiting for a new 74ACT00 to solder, I would like to know what would be the causes for the 74ACT00 getting fried.
I have to mention that I had tested the new classic board without L15 on the board until I saw that there was no power coming out, and saw that L15 was missing.
I soldered L15 and all went just fine, until a few minutes, when the 74ACT fried.
Would L15 missing be enough to cause this ?
My mainboard is one of the first batches from *Rxxxx*, and the classic board a new one from approved dealer.
U1-74ACT00 fried
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- Posts: 399
- Joined: 30 Dec 2021, 22:54
Re: U1-74ACT00 fried
Hello OM,
Rxxxx changed maybe the main board, but it is also not good to use the Drive chain without power source connected trough L15 to the PA FETs
I would also check the PA FETs and RX mute switch Q1 before using it with another 74ACT00.
73 de Chris
Rxxxx changed maybe the main board, but it is also not good to use the Drive chain without power source connected trough L15 to the PA FETs
I would also check the PA FETs and RX mute switch Q1 before using it with another 74ACT00.
73 de Chris
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
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- Posts: 9
- Joined: 22 Mar 2022, 22:19
Re: U1-74ACT00 fried
Hello all !
I replaced the fried 74ACT00 with a new one.
On another RF board that I have with 3 BS170, the (tr)uSDX works.
With the new board with FDT86256, I dont have power.
Is there a good way to test the FDT86256 ?
It probably also fried because of the lack of L15 in the inicial test.
I replaced the fried 74ACT00 with a new one.
On another RF board that I have with 3 BS170, the (tr)uSDX works.
With the new board with FDT86256, I dont have power.
Is there a good way to test the FDT86256 ?
It probably also fried because of the lack of L15 in the inicial test.
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