The resistance across B+ and ground is .4 ohms.
Aqeeb127 - I measured the diode resistance and its .3 ohms. It doesn't matter if I switch the leads end to end it reads the same both ways. Should it block the flow in one direction? I don't have a diode setting on my dmm. The diode is soldered to the board, I don't know if it can be tested while its attached.
Aqeeb127 - I measured the diode resistance and its .3 ohms. It doesn't matter if I switch the leads end to end it reads the same both ways. Should it block the flow in one direction? I don't have a diode setting on my dmm. The diode is soldered to the board, I don't know if it can be tested while its attached.
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The diode and the PS FETs are across the B+ and ground. It's easier to check the diode first (desolder and check).
If it's OK (it's likely shorted). Measure the resistance between legs 1 and 2 of the PS FETs. They shouldn't read anything near 0 ohms (more like 100 ohms). If they read shorted, remove them and check them out of the circuit.
If it's OK (it's likely shorted). Measure the resistance between legs 1 and 2 of the PS FETs. They shouldn't read anything near 0 ohms (more like 100 ohms). If they read shorted, remove them and check them out of the circuit.
One ps fet measures 100 ohms across legs 1&2. The other fet is 1.7 ohms across 1&2. Should I go ahead and desolder the diode to check it? I suppose there is likely multiple things wrong here.
You can desolder (and clean the pads for the FET to eliminate the possibility solder bridges) and re-check the resistance across the B+ and ground.
Lay your iron across all 3 solder pads and when the solder melts, pull the FET out. The tab of the FET will get hot so be careful.
Lay your iron across all 3 solder pads and when the solder melts, pull the FET out. The tab of the FET will get hot so be careful.
OK I learned that I want one of those solder suckers. I really had to fight that thing to get it out. With the offending fet removed the bat+ to ground measures open.
DS017 purchased directly from Edsyn site to avoid counterfeits.
Laying the iron down and heating all 3 terminals should have made it almost fall out.
Laying the iron down and heating all 3 terminals should have made it almost fall out.
Should I replace both of them at the same time? Is there another component that could have caused this one to fail that I should check? The power supply diode perhaps?
The RP diode is there in case the amp is connected with reverse polarity.
Both FETs need to be replaced. Do you now read 100 ohms from pad 1-2 for the FET you removed?
Order the FETs from Mouser or digikey. Order a few extras. Do NOT buy them (or the DS017) from ebay. Order the IRFZ44.
Both FETs need to be replaced. Do you now read 100 ohms from pad 1-2 for the FET you removed?
Order the FETs from Mouser or digikey. Order a few extras. Do NOT buy them (or the DS017) from ebay. Order the IRFZ44.
The manual calls for IRFZ44 60v/35a/.028 ohm
The ones I can find have suffexes on them...
Https://www.mouser.com/ProductDetai...iMZZMshyDBzk1/Wi5%2bqVgN3%2bWS8T%2bK1ofX17ZA=
I measured from 1-2 where the fet had been on the board. The multimeter danced around a bit then settled on open. The other fet is still installed. Shall I remove it and measure again? When I check the other fet that is still installed the reading is different than what I had initially. Now it reads open between 1-2.
The ones I can find have suffexes on them...
Https://www.mouser.com/ProductDetai...iMZZMshyDBzk1/Wi5%2bqVgN3%2bWS8T%2bK1ofX17ZA=
I measured from 1-2 where the fet had been on the board. The multimeter danced around a bit then settled on open. The other fet is still installed. Shall I remove it and measure again? When I check the other fet that is still installed the reading is different than what I had initially. Now it reads open between 1-2.
Yes they both read the same. Would you mind looking at this fet and tell me if it would be a good one to buy?
IRFZ44EPBF Infineon Technologies | Mouser
The manual calls for IRFZ44 60v/35a/.028 ohm
IRFZ44EPBF Infineon Technologies | Mouser
The manual calls for IRFZ44 60v/35a/.028 ohm
When you initially power the amp up after replacing the FETs, I'd suggest clamping everything down and using a 5 amp fuse instead of the 20 amp fuse. This will offer better protection for the various components in case there is another problem.
One more thing you could check is the drive on the gate pads. The manual says that you should see about 4v DC.
One more thing you could check is the drive on the gate pads. The manual says that you should see about 4v DC.
Meanwhile, do you have a picture of the small driver board or maybe a schematic of it from your technical manual? I recall fixing a JBL amp (GTQxxx) a couple of years ago by replacing a small transistor on the driver board. I remember having an NTE equivalent in my stash which I used to confirm the fix but replaced with the actual part later on.
Damuho - the technical manual is available here:
Download JBL GTS100 Technical Manual
I can take any pics of the board you want, if you need more than just the manual. Let me know.
Download JBL GTS100 Technical Manual
I can take any pics of the board you want, if you need more than just the manual. Let me know.
Not sure if you've changed the FETs but just as a quick check, look at the small PWM module and see if you can detect a short on either of the complementary MPS2907 and MPS2222 transistors. Specifically, check between the collector and base (middle and right pins) of both devices.
Thanks damuho. I lost my place and had to put this and all my other projects in a storage unit for now. It may be a while, but I'll get back to this.