HP 1502 (P9617D) pulsing on and off with bad capacitors

[japlytic]

Today, my daughter's HP 1502 (P9617D) monitor (3 years old) was pulsing on and off (with a flash of video). I tried it on another computer with the refresh rate set within the monitor's specifications - same result.

Later, I opened up the monitor and found that all but two (one of them was an LZ series unit) of the low-ESR Hermei capacitors have bulged .

The list of the capacitors used as below (I cannot find datasheets for the Hermei units) :

C922, C925: Hermei LE 1000uF 16V, low impedance, general purpose, replacing with 1000uF 16V Samxon GF.
C201: Hermei LZ 150uF 25V, ultra low impedance, high ripple current, replacing with 1000uF 25V Samxon GF.
C924, C926, C929, C930, C932, C933: Hermei LT 470uF 16V, high ripple current, low impedance, replacing with 1000uF 16V Samxon GF.
C207: Unknown CD110 50uF 4.7uF (general purpose), replacing with a 35V 4.7uF tantalum unit (SCP/Short Circuit Protection pin on TL1451 won't get anywhere near 35V).
C907: WC (with stylized Westinghouse W) SM 22uF 50V (general purpose), replacing with 63V 100uF Samxon GF (used for SMPS controller Vcc filtering).
C905: Hermei HT 100uF 400V, standard, general purpose, leaving as is - generally no problem.

[JPack]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

[argus]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

Sorry to drag up an old post. I've just repaired the same monitor based on your parts list so Thank you very much!.

I used a 470uF 25V cap in place of C201 cause I couldn't get the 1000uF to fit. Still a good margin over the original 150uF. Will this be OK?

There is a surface mount zener that has become quite hot. It is marked 7.5B 36 (the 36 could be 35 or 3S) the last character is difficult to make out. I did not replace it because I could not identify it but the screen is working ok.

I notice it had been hot on yours too based on the photo. Would it be worth replacing and if so what wattage would the original surface mount part be?
A through hole 1W 7V5 zener would fit in its place would that be sufficent?

[davmax]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

Zener diode. Have you checked that there is 7.5 volts across this device? best measure it whilst it still works. Remember that an SMD device has better heatsinking than the normal wired type. You should be able to work out what power it is currently dissipating if you can identify the resistor in series and the voltage drop across it. Current I = E/R Zener watts = Vz x I

Is the 470U 25V cap a low ESR type?

[argus]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

Yes I used low ESR for all the replacements.

I'll look at measuring the zener

Thanks!

[vince88]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

The same "power board 715L1034-1" circa October 2003 with potentially faulty HERMEI caps is used in a number of lCD monitors, including HP1502, Compaq FP15 & FP5315, Iyama PLE383, etc. The message posted in this forum as "Compaq FP15" also applies to HP1502. Here it is.
++++++++++++++++++
I just repaired a Compaq 15" LCD screen Model FP15 Model Number PE1233 Product Name P9618C Manufactured in October 2003; it is similar to HP1502. This LCD has 2 boards, one 'power-backlight board' reference 715L1034-1 and one 'processor board'. This 715L1034-1 seems to be used by quite a few other lCD e.g. Ilyama, etc.
The 'power board' 715L1034-1 was not working. Main issue with the 'power board' were 7 HERMEI capacitors that had "bulged at the top and popped the rubber seal at the bottom", out of a total of 10 HERMEI capacitors on the board. I am surprised that Compaq/Hp used as late as October 2003 caps that have been considered as questionable since 2000 :-( .
I replaced these seven capacitors including 5 rated 470micF/16V [C926, C924, C929, C930, C930] and 2 rated 1000micF/16V [C922 & C925].

Due to these faulty caps, Zener diode ZD904 [7.5V, 150mW] had overheated and left a visible burnt mark on the pCB, but it was still working; ZD904 can be tested in circuit by connecting +12V through a serie resistor to the Zener and measuring the voltage across the Zener; should be 0.7V one way and 7.5V the other.

After recapping, the FP15 LCD monitor is now working.
By the way, a decent 'Service Manual' of the power board can be found at http://www.eserviceinfo.com/index.p...ring=vf15++fp15 but the component reference number have changed by 100 e.g. component C922 on the board will be C822 in the service manual. Hope this helps.

The faulty HEMEI's are either purple or black [*C stands for degrees C]:
- purple 470micF/16V marked LT 105*C 0326, diameter: 8.2mm & height: 12mm
- black 1000micF/16V marked LE 105*C 0331, diameter: 10.1mm & height: 15mm.
I enclose a photograph of some of the 7 faulty caps. Good photographs of the 'power board' 715L1034-1A and another example of 'bulged capacitors' can be found in the 'allinbox' forum at http://forum.allinbox.com/aspectgee...ujet_8417_1.htm
Vince

[vince88]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

The same "power board 715L1034-1" is also used in BenQ FP15 and what seems to be a clone sold as Dell. I wonder how many LCD monitors use this 'power/backlight' board with potentially faulty HERMEI's ?
Vince

[stuart06]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

First of alll I would like to thank you all for the info posted and I would also like to add the Hp Pavilion f1523 monitor to the list suffering from the same defects.
Replaced the 7 defective components and the monitor is working as good as new.
Thanks again.

[nomakon]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

Replaced the 7 defective components and the monitor is working as good as new.

Me too TY FOR ALL!!!!!

DZ903 is replaced with zenner 7.5V 500mW NO SMD and OK!!!!

[gonzo0815]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

The zerner is used as an crow bar circuit. It shorts out, when the voltage and thus the current trough is getting to high.
If the cap on the regulated voltage rail is getting bad, usually the other rails are going up.
I have seen bad zener in many such psu`s in various appliances.

[teds01]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

Thanks to all! using the parts list from Japlytic, I have successfully repaired a number of the HP 1502 monitors.

They all seem to work fine now, considering this is the first time I have used a soldering iron, and also recapped a board. All thanks to the resources in this forum, cheers!

[Krankshaft]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

The classic Hermei capacitor failure I really do hate those caps.

Purple with the turtle shell vents give them away.

Hopefully in order to evade legal action for their poor quality products they changed their name to something else already .

[punkthrasher]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

same problem with me but after replacing all the faulty cap. the monitor won't turn on, when power applied the power led only blink once after that nothing. Any idea whats wrong.

[Krankshaft]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

Check the inverter drive transistors for shorts they are near the high voltage transformer.

They are located above and below that fat blue cap.

[Brian C]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

Replaced the 7 defective components and the monitor is working as good as new.

Me too TY FOR ALL!!!!!

DZ903 is replaced with zenner 7.5V 500mW NO SMD and OK!!!!

Judging from the size of DZ903, it should be 7.5V B-rank 1000mW Zener Diode.
http://www.rohm.com/products/databoo...df/ptz7.5b.pdf

[Brian C]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

My mistake... ZD904 is SMD 1W 7.5V Zener Diode. ZD903 is axial 5.1V Zener.

[monrepguy22]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

Hey guys-thanks for this awesome post.

I got an Hp 15" for free-exhibiting the same symptoms as you guys have said. I have very limited soldering and electronics repair experience, but I replaced 5 of the 7 capacitors you said were faulty-only 5 of them were bulging. My monitor now stays on and holds a video signal, but for some reason it displays too many red pixels, making the image nearly unusable. Do I need to replace the other capacitors? I know the video signal coming from the computer is good-tried it on 2 other monitors....Could it be a video signal problem in the monitor? What would you recommend?

Thanks

[humphrey]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

It would make sense to change all the caps with the exception of the 100mFx400v as they have been exposed to the same conditions.

[gwbm]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

Thanks to this thread I was able to fix my HP f1523 which exhibited the classic on-off cycling behaviour. Interestingly, I found that all 7 of the notorious Hermei capacitors looked fine, but the 1000 uF 16v Elite EX capacitor (C925, black with light blue polarity stripe) was bulging badly. I replaced it and the monitor is now fine!

Thanks again

[arneson]

Re: HP 1502 (P9617D) pulsing on and off with bad capacitors

My monitor had a triple whammy.
All the smaller caps shown were bulged and shot,
and the 400v main power filter was totally crispy critter,
and two of the inverter drivers were shorted.
My fear is that if I get it to light up
I'll find someone got pissed and punched the screen.