Help diagnosing SM Power Supply board for video projector - Page 1
Forum section: electronics / repair

author: ^Gecko^
author_rank: Newbie
timestamp: July 25, 2018, 06:28:21 am
content: I'm been following the voltage with my meter and I have around 154vdc going in to the switching chip IC651, but I am measuring nothing on the outputs going to the transformer. Is it safe to assume that the switching regular has gone tits-up? Or should I be looking at IC601 (under a big choke coil) ? The datasheet for that part is completely unavailable. I emailed the manufacturer and they tell me it's a custom chip and that they can not give me the datasheet because of that.

author: eblc1388
author_rank: Frequent Contributor
timestamp: July 25, 2018, 07:04:02 am
content: If you are seeing 154V dc, then the power factor correcting circuit is not functioning or disabled. The voltage on the high voltage electrolytic capacitor C616 should be about 380V or more.The datasheet of the FA5332M(IC601) is available at the following site:https://html.alldatasheet.com/html-pdf/61401/FUJI/FA5332M/81/1/FA5332M.html

author: ^Gecko^
author_rank: Newbie
timestamp: July 26, 2018, 12:11:22 am
content: Thanks. Yeah I'm only getting the same 154vdc across that capacitor too. It could also explain why I'm only getting around half a volt at output K6A (to the lamp ballast board)The only way I can get my probes in to IC601 is to remove the big choke (current transformer?) T601

author: eblc1388
author_rank: Frequent Contributor
timestamp: July 26, 2018, 07:10:09 am
content: From my understanding of the circuit, the 154V rectified ac voltage should be sufficient to start the switching regulator STR-Z2156 and produce secondary voltages. Then some feedback circuit via the optocoupler PC603 pin#4 would go low and enable the PFC function via stopping the conduction of Q623. IC601 pin#12 goes high and PFC runs and produce 380V on the rail, whereas switching regulator would response and maintains the correct voltages at the secondaries.I'm sure at present pin#4 of PC603 is several volts w.r.t. the negative terminal of high voltage capacitor C616. If this is the case, then the PFC function is not activated.The chance of switching regulator STR-Z2156 failure is high. Unfortunately, I couldn't locate a datasheet for this chip so I can't say for sure if it will work with 154V or not.

author: Chris56000
author_rank: Frequent Contributor
timestamp: July 27, 2018, 04:47:33 pm
content: Hi!Can I ask what Make & Model your Projector is please?It looks there's a good service manual available – if you could provide us a link to the Manual or full model details I can examine it in more detail and come back with further fault– finding advice if you need it!Chris Williams

author: tibimakai
author_rank: Contributor
timestamp: July 29, 2018, 03:29:06 am
content: That would be helpful.I have repaired recently, a Benq 1070 and the IC PMD1000(HDMI board) and a shorted capacitor were causing the problem.

author: ^Gecko^
author_rank: Newbie
timestamp: August 11, 2018, 06:08:57 pm
content: Quote from: Chris56000 on July 27, 2018, 04:47:33 pmThe projector is an Eiki LC-X1100. I have a few of them, none of them power up at all, and I'm assuming that they all have the same problem.I found the electrical schematic from here:https://elektrotanya.com/eiki_lc-x1100_lc-x986.pdf/download.html

author: Chris56000
author_rank: Frequent Contributor
timestamp: August 13, 2018, 04:14:07 am
content: Hi!Thanks for confirming the details!I've just got my new work table up at home and pride of place on it will go a new colour laser, so I'll get printing & get back with step–by–step fault–finding advice as soon as I can!Chris Williams

author: ^Gecko^
author_rank: Newbie
timestamp: August 23, 2018, 12:33:13 am
content: Those are, of course, only the electrical schematics. I haven't been able to find the proper service manual for the projector as a whole (exploded diagrams, etc) for the chassis.

author: ^Gecko^
author_rank: Newbie
timestamp: October 28, 2019, 08:11:54 am
content: How's it going? I know it's been a long time since my last post on this topic, and that's where my project and troubleshooting had ended. I've gotten a bit of motivation to look into it again, and my new question is what the hell is so special about IC651 (STR-Z2156) that I can't get some other similar part to replace it? I can't find anything like it on digikey or mouser, maybe I'm not looking in the right place.I did however find an internal schematic for the chip itself.http://igorx.irk.ru/datasheet/5431DX23YOvBpG7Uc2yk.pdfI'm also curious what the system would do if I just fed in 16, 6, and 6(or 5?) volts (ac? dc?) where the transformer outputs are.