Emerson EWC0902 - CRT Repair - Page 1
Forum section: electronics / repair

author: TexasAggie15
author_rank: Newbie
timestamp: August 11, 2025, 02:11:55 pm
content: Hi,First timer here. Mechanical engineer by education and trade. For some background, last year I picked up a flipping side-hustle, and with that often time I acquire broken items in need of repair. I recently picked up an Emerson EWC0902 9" CRT/VCR combo unit. Physical condition but it wouldn't power on. Opening it up (I am aware of the dangers and take precaution), I noticed R589 and R590 were fried (Linking the circuit diagram from manuallibs- page 47). These two are a part of the h-drive circuit. From some research (12voltvids on youtube) and discussion with ChatGPT, I understood to check the h-drive transistor (Q572) and HOT(Q571). If the HOT latched on, it likely pulled too much current through the H-drive circuit and blew the resistors. I pulled both out of circuit. H-drive measured good on a diode test. HOT measured 0.06V from B to E so I bought a new, beefier model per recommendation of ChatGPT. I also reflowed the solder joints on the h-drive transformer (T572) With a new HOT and new resistors (1/2 watt because that's what I had), I put the device on a 100W dim bulb tester. Upon plugging it in the bulb shone bright and then dimmed and the tv a brief whining noise alongside the bulb shining. Upon powering it up, the bulb shone bright again briefly and then dimmed, and I heard the familiar noise of a CRT kicking on. I got the menu on the screen. All looked well and good. So I powered the device off. Let it sit for a while, and powered it on again. All the same things happened. But on the third time, when I tried to turn it on from the remote control, the bulb started to dim and then the bulb shone bright and I heard a whining coming from the tv. No screen action. I immediately shut it off. I pulled the HOT back out and it is at least still measuring good on a diode test. I'm looking for some direction. I am leaning towards the flyback being borderline? Could it be the dim bulb tester? I had a larger CRT tv cycle on and off on the same 100W bulb because it couldn't draw enough starting current to stay on. In that case the bulb flashed bright on and off. I don't know what else could have gone wrong. I am limited on what I can test and measure as my arsenal of tools is still building. I have a multimeter and an ESR.TL;DRI have an Emerson EWC0902R589 & R590 in the H-drive circuit were fried and replacedHOT (Q571) B to E measured 0.06V on diode test so it was replaced with a new oneH-Drive measured good on diode testReflowed H-drive transformer (T572) solderPut device on 100W Dim bulb tester, it started and shut down twice fine. The third time the bulb stayed brightB+ measured 112V (should be 117 according to the manual) but it was on the 100W dim bulb testerLooking for help

author: Uunoctium
author_rank: Frequent Contributor
timestamp: August 11, 2025, 03:16:38 pm
content: The first, i would have a closer look on the two capacitors in parallel to primary winding of HOT (horizontal output transformer) - C680, C681. In doubt, desolder and measure them. In case they need to be replaced, use FKP with a minimum of 1.500V.Next suspicious could be any diode, diode/electrolytic combination on auxiliary windings at HOT. (D584, C584 or D585, D572)

author: TexasAggie15
author_rank: Newbie
timestamp: August 12, 2025, 11:53:40 am
content: For measuring the high voltage capacitors, is a simple capacitance measurement sufficient? They appear physically fine, and I don't think my multimeter goes into the low picofarad range. I've been planning on picking up an inexpensive LCR meter, so I could grab that and measure them. I'm wondering if the capacitors are breaking down at high voltage?

author: Uunoctium
author_rank: Frequent Contributor
timestamp: August 12, 2025, 03:52:02 pm
content: The two capacitors (together acting as one) are essential fora) the high voltageb) the picture widthand they are often faulty or have bad solder joints by themselves.Your test with the bulb in series, and the fact that a picture appeared, suggests that the HOT (Horizontal Output Transformer) is probably okay (high voltage present, filament heats). However, this is not 100% guaranteed.There must therefore be another part of the circuit drawing much more current than normal, and connected to the HOT. Otherwise, the driver transistor and resistor would not have been destroyed by overload.For that reason, you should check all pathways connected to the HOT – especially those that are rectified and smoothed by a capacitor – for purposes such as beam current limiting or flyback energy recovery to supply the vertical power line.

author: TexasAggie15
author_rank: Newbie
timestamp: August 12, 2025, 04:10:30 pm
content: To clarify, the h-drive transistor did not fail as far as I know. It measured ok per a diode test. The HOT is what was failed and replaced. Once it was replaced, the TV functioned normally twice for <1 min test runs. The third time I turned it on is when the dim bulb stayed bright and the screen shut down.I see the AFC and ACL on secondary windings. I can check components there as well.