Re: BT139-600G Triac Equivalent
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).
RE: BT139-600G Triac Equivalent
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-boun...@classiccmp.org] On Behalf Of Peter > Coghlan via cctalk > Sent: 17 December 2017 13:25 > To: cctalk@classiccmp.org > Subject: Re: BT139-600G Triac Equivalent > > > > > 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.
Re: BT139-600G Triac Equivalent
On 12/17/2017 08:24 AM, Peter Coghlan 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. >> > 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. > 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
Re: BT139-600G Triac Equivalent
> > 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.
BT139-600G Triac Equivalent
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
