45" Pioneer projo model:SD-P4571K/KC

45" Pioneer projection tv model:SD-P4571K/KC,year:Nov 94.Intermittent flashing picture with no audio and lines running across screen (left to right) while problem present.When menu button is pressed picture and sound come in perfect but customer can't watch with menu screen on as it's obviously annoying.

Eventually after about 15 minutes or so picture looses severe convergence and the bottom of the picture curves upwards and the top of picture is curver upwards as well.

When tv looses convergence menu can longer be accessed and channels cannot be changed only volume and power but no OSD bar for volume.I can no longer access RCA input jacks. When tv is first turned on from a cold start I can access RCA input jacks with perfect picture & sound but when switched to tuner input picture begins to flash.

I replaced the 3 electrolytic capacitors in the seperate IF block:

C22=0.47 uf,50v C26=0.47 uf,50v C05=47 uf,16v

I also resolder IF block,tuner and lots of parts on many boards,I don't repair projection tv's nor do service/pickup calls but this one is an exception. Anyone have any common repair tips for me?.Thanks in advance.

Sidney E-mail:sidneybek(at)yahoo.com Dartmouth,Nova scotia Canada

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Found these for you:

Symptom: Picture fades in and out. Color fades in and our. "Piecrusting" etc. This occurs on video inputs as well as tuner inputs. Cure: 9V supply is unstable and voltage is too low. Replace C129 on power supply assembly.

Symptom: No tuner video/audio All other inputs ok. Replaced tuner & IF packs twice, IC451 (PD5217B) once, and still had same problem. All tuner voltages present. Cure: Confirmed IF pack by injecting IF signal. Confirmed tuner by manually varying VT. Discovered missing PLL Enable signal. (Last pin on Tuner Assy). Found glue had corroded a trace off pin 46, IC451. (Near J624 & J645). Repaired trace and restored normal operation.

Symptom: SYMPTOM: REPEATED FAILURES OF TUNER. CAUSE: DEFECTIVE Q112 IN Cure: POWER SUPPLY CAUSING 13.5V LINE TO BE AROUND 17V

Symptom: SYMPTOM: NO VIDEO, AUDIO OK, OSD OK, TEST CROSS PATTERN OK. Cure: CAUSE: DEFECTIVE A/V IO PINP Y/C SEP. ASSY.

On the symptom of loss of convergence / control. I'd check all power supplies to see if they7 remain stable, esp. the +5 standby, noise could be causing misoperation of the microprocessor. Could also be a defective micro or NVRAM IC.

Has this set had the shield plate put in to protect the micro? These had a problem in early production with static discharge from the CRT's toasting the uP, if I recall correctly.

Jammy