Author Topic: Technical opnion about wave generator with problem  (Read 2693 times)

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Offline israelTopic starter

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Technical opnion about wave generator with problem
« on: August 08, 2013, 11:03:48 pm »
Hi guys.

I have this wave generator with some problems, are all under control except the display indication ... is dead

I have seen that there is voltage in pin 3 of IC that varies as a function of the position of the frequency control. i suspect that the reason that the display does not show anything could be the IC HEF-4379VP

there a reliable way to know if the problem is that IC?
I have found on the internet but is quite expensive. and before buying I would like to have some more expert opinion.

attached images to see the team and the IC.


sorry for my terrible english :-[


Best regards
 

Offline AlfBaz

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Re: Technical opnion about wave generator with problem
« Reply #1 on: August 08, 2013, 11:29:47 pm »
Have you checked for any output on the scan and data out pins?
 

Offline tinhead

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Re: Technical opnion about wave generator with problem
« Reply #2 on: August 08, 2013, 11:34:11 pm »
the right trim pot didn't look good, check it first.
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Offline fpliuzzi

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Re: Technical opnion about wave generator with problem
« Reply #3 on: August 09, 2013, 12:25:17 am »
Hello,
The socket that the HEF-4379VP sits is in may be as tarnished as the right hand trim pot that tinhead pointed out. if you haven't done so already you may want to try lifting the chip up a bit on each side and then reseating the HEF-4379VP. The pins may be making poor contact. Worth a try anyway.

Regards,
Frank

 

Offline israelTopic starter

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Re: Technical opnion about wave generator with problem
« Reply #4 on: August 10, 2013, 11:14:00 am »
Quote
Hello,
The socket that the HEF-4379VP sits is in may be as tarnished as the right hand trim pot that tinhead pointed out. if you haven't done so already you may want to try lifting the chip up a bit on each side and then reseating the HEF-4379VP. The pins may be making poor contact. Worth a try anyway.

Regards,
Frank


was one of the first things I thought.




I researched a little more, and I think that might be the IC makes the voltmeter function to control the display  :'( :'(

I thought at the decoder, but this was fine.


Anyone know where I could get cheap HEF4739VP?
The only site I found sells it at $ 62 + shipping


Regards,
« Last Edit: August 10, 2013, 11:19:50 am by israel »
 

Online PA0PBZ

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Re: Technical opnion about wave generator with problem
« Reply #5 on: August 10, 2013, 11:48:26 am »
Are there any pulses on the scan lines (pins 10 - 13)?
Is the thing oscillating (pin 25)?
Keyboard error: Press F1 to continue.
 

Offline israelTopic starter

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Re: Technical opnion about wave generator with problem
« Reply #6 on: August 10, 2013, 03:45:33 pm »
Quote
Are there any pulses on the scan lines (pins 10 - 13)?
Is the thing oscillating (pin 25)?



The tests show these results:

1 --- 10.6820 v fixed
2 --- GND
3 --- The voltage varies according to the frequency and amplitude -4 mv to 1.8 volt
4 --- 3.8993 v fixed
5 --- no voltage
6 --- 6.6758 v fixed
7 --- no voltage
8 --- 3.6862 v fixed
9 --- no voltage
10 -- 1.3440 v fixed
11 -- 4.9380 v fixed
12 -- 1.3462 v fixed
13 -- 1.3460 fixed
14 -- no voltage
15 -- 5.114 v fixed
16 -- 1.4945 v fixed
17 -- 5.127 v fixed
18 -- 3.3385 v fixed
19 -- no voltage
20 -- no voltage
21 -- 4.9771 v fixed
22 -- 4.9797 v fixed
23 -- 3.5055 v fixed
24 -- 4.9796 v fixed
25 -- 3.2070 v fixed (no clock in scope)
26 -- 3.3875 v fixed (not response at 250 khz)
27 -- 4.9796 v fixed
28 -- 4.9820 v fixed




I see that pin 25 delivers no signal, according to the manual the clock signal is 250 KHz. I tried to inject a 250 KHz signal on pin number 26 (clock input) to see what happened, but there is no result.

« Last Edit: August 10, 2013, 03:47:10 pm by israel »
 

Online PA0PBZ

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Re: Technical opnion about wave generator with problem
« Reply #7 on: August 10, 2013, 03:58:38 pm »
Well, if the thing is not oscillating and there is a supply voltage, it might be dead, I don't see anything like an enable line...
All you can do is check the L, R and C on the clock pins, but if these are OK I think it's game over for the IC.
I did a quick search and all I found is the one you found too for $62.
Keyboard error: Press F1 to continue.
 


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