Panasonic PT-L735 - Page 1
Forum section: electronics / repair

author: asp
author_rank: Regular Contributor
timestamp: December 25, 2018, 08:42:27 am
content: HiCan anyone please point me in the right direction for fixing my Panasonic projector? The Lamp was dead so I got a new one but it never started either, so I opened the power source and found 2 IGBTs that ware in short (Q9608 and Q9609 from the attached schematic). In reality Q9608 and Q9609 are 20J321 and I replaced them with GT20J341What I suspect might be bad as well is also Q9606 but for the life of me I can't find a 2SB0710 transistor (I know aliexpress has some but wouldn't want to wait 1 month for it to get here) so I ordered this onehttps://www.tme.eu/en/details/pmbt2907a.215/PMBT2907A.215; should that be a good replacement? .What else should I look for? IGBT Driver? Some other parts? Thanks

author: Armadillo
author_rank: Super Contributor
timestamp: December 25, 2018, 09:50:29 am
content: Firstly, don't install the 2 IGBTs, you need to ensure that both bases are not high at same time.A. Measure Voltage at IC9602 - Pin 4 wrt Pin 3 and Pin 7 and Pin 3, make sure both not high at same time.B. Then, make sure T9604 are not fused/shorted. You have to take it out to ring test it.If both pass, then install the IGBT and run it using series light bulb test.Above my opinion, the way I would proceed it.

author: asp
author_rank: Regular Contributor
timestamp: December 25, 2018, 11:56:40 am
content: Thanks Armadillo.Just an update...I tested and it seems D9608 is bad as well and I have no idea what to replace it with. On the package it's written M2W and it's a SOT-23. Any ideas?Q9608 is shortened between E and C and Q9609 between all 3 pins

author: Armadillo
author_rank: Super Contributor
timestamp: December 25, 2018, 12:01:02 pm
content: MA720Quote from: asp on December 25, 2018, 11:56:40 am

author: Armadillo
author_rank: Super Contributor
timestamp: December 25, 2018, 12:06:55 pm
content: Quote from: asp on December 25, 2018, 11:56:40 amAlternatively, remove IC9602 and measure [Or remove any other shorts and measure]Pin 6 and Pin 7 > 3 KohmPin 4 and Pin 3 > 3 Kohm

author: asp
author_rank: Regular Contributor
timestamp: December 25, 2018, 12:26:23 pm
content: Quote from: Armadillo on December 25, 2018, 12:06:55 pm6-7 ~ 6.2K3-4 ~ 8.4K

author: Armadillo
author_rank: Super Contributor
timestamp: December 25, 2018, 01:00:12 pm
content: With a short such like this, I would be surprise if R9601 or the fuse still survive.

author: asp
author_rank: Regular Contributor
timestamp: December 25, 2018, 01:41:44 pm
content: Quote from: Armadillo on December 25, 2018, 01:00:12 pmcan't find any fuse except 2 main ones which are ok since the projector worksexcept for the lamp powering onR9601 seems to be doing quite wellAnyway now I have to wait till 2nd of Jan to get the components and see if it works (i just hope PMBT2907A.215 is a good replacement for 2SB0710)thanks for the help

author: asp
author_rank: Regular Contributor
timestamp: January 03, 2019, 12:53:29 pm
content: After changing the IGBT’s (Q9608 and Q9609), the diode (D9608), transistor (Q9606) and IGBT controller (IC9602).... the proiector is alive...again.I think what caused everything was D9608. I was not in short but had a lower than expected resistance (22ohms)Thanks again for the help