17 Dec
2017
17 Dec
'17
3:23 a.m.
I have a suspicion that this component may be faulty on the input side of my
H7826 PSU. A little tester I have does not recognise it, it is possible that
the currents it uses are too low for this particular triac, but I am not
sure.
There are new ones on ebay, but I am not sure if I can trust ebay sellers to
have genuine parts. So I would like to identify a suitable replacement. I
have found a few suggestions for replacements, but looking at the datasheets
many seem to have a lower peak gate power then the BT139. I am not sure what
the critical parameters are, so I don't know how to choose a replacement.
Can anyone suggest a good replacement for this part?
Thanks
Rob
17 Dec
17 Dec
5:24 a.m.
I have a suspicion that this component may be faulty on the input side of my
H7826 PSU. A little tester I have does not recognise it, it is possible that
the currents it uses are too low for this particular triac, but I am not
sure.
What is the function of this triac in your power supply?
I have come across a triac which is used to switch between 115V and 230V input
in the PSU of a DEC 3000/300. My triac went short circuit which caused some
release of magic smoke when the PSU was used on 230V. I also had difficulty
finding a replacement for it so I ended up leaving it out. The PSU worked
fine on 230V only without it once I replaced the other damaged components.
If your triac has a different function, ignore the above.
Regards,
Peter Coghlan.
6:23 a.m.
On 12/17/2017 08:24 AM, Peter Coghlan via cctalk wrote:
OUTPUT CROWBAR:
The common use is to create a hard short circuit across the output if
the output voltage
exceeds a safe limit.? The logic is that a power supply is cheap
compared to the rest
of the computer.? The typical output where this is done is the 5V rail.
The tester likely cannot test a triac its not a simple transistor or
diode.? They are easy to test
a light bulb (12V) and a DC source.
Allison
I have a
suspicion that this component may be faulty on the input side of my
H7826 PSU. A little tester I have does not recognise it, it is possible that
the currents it uses are too low for this particular triac, but I am not
sure.
What is the function of this triac in your power supply?
I have come across a triac which is used to switch between 115V and 230V input
in the PSU of a DEC 3000/300. My triac went short circuit which caused some
release of magic smoke when the PSU was used on 230V. I also had difficulty
finding a replacement for it so I ended up leaving it out. The PSU worked
fine on 230V only without it once I replaced the other damaged components.
If your triac has a different function, ignore the above.
Regards,
Peter Coghlan.
11:07 a.m.
Thanks Peter,
Now that you mention it, I have heard that these triacs get used in the auto
voltage detection. I was about to reverse engineer the schematic and that is
now my next step. I would still like to identify possible replacements
though in case I ever need spares for this part.
Regards
Rob
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Peter
Coghlan via cctalk
Sent: 17 December 2017 13:25
To: cctalk at classiccmp.org
Subject: Re: BT139-600G Triac Equivalent
caused
I have a suspicion that this component may be faulty on the input side
of my
H7826 PSU. A little tester I have does not recognise it, it is
possible that the currents it uses are too low for this particular
triac, but I am not sure.
What is the function of this triac in your power supply?
I have come across a triac which is used to switch between 115V and 230V
input in the PSU of a DEC 3000/300. My triac went short circuit which some release of magic smoke when the PSU was used on
230V. I also had
difficulty finding a replacement for it so I ended up leaving it out. The
PSU
worked fine on 230V only without it once I replaced
the other damaged
components.
If your triac has a different function, ignore the above.
Regards,
Peter Coghlan.
1:05 p.m.
On 2017-Dec-17, at 3:23 AM, Rob Jarratt via cctalk wrote:
I have a suspicion that this component may be faulty
on the input side of my
H7826 PSU. A little tester I have does not recognise it, it is possible that
the currents it uses are too low for this particular triac, but I am not
sure.
There are new ones on ebay, but I am not sure if I can trust ebay sellers to
have genuine parts. So I would like to identify a suitable replacement. I
have found a few suggestions for replacements, but looking at the datasheets
many seem to have a lower peak gate power then the BT139. I am not sure what
the critical parameters are, so I don't know how to choose a replacement.
Can anyone suggest a good replacement for this part?
Any parameter can be critical, depending on how the device is being used.
The parameters primarily or commonly of issue with triacs are the peak blocking voltage
and the RMS conducting current.
The gate power is going to be a function of the trigger circuitry, so one isn't going
to know for sure without analysing the trigger circuit design.
With that said, gate circuits are generally designed for fairly low-level operation and
not to be using a lot of power.
If this triac is on the input side and just used as a switch for input voltage selection,
the requirements are probably pretty generic.
The Q-thousand series of triacs are (were?) pretty common:
https://www.digchip.com/datasheets/parts/datasheet/472/Q2003L-pdf.php
Try comparing with the Q6015L5 (pdf.32-33).
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4 comments
4 participants
participants (4)
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allisonportable＠gmail.com -
bhilpert＠shaw.ca -
cctalk＠beyondthepale.ie -
robert.jarratt＠ntlworld.com