Compaq TFT5010 rack mount monitor

[severach]

I have a Compaq TFT5010 with no backlight. There was a bad cap SMD 100uf 16v C160 on the video board but that may not have been the problem since the Compaq logo was visible on the unlit display. All the 100uf 16v SMD caps on the video board show poor ESR. There was a bad cap Sanyo 100uf 25v C23 on the inverter. At first I ignored it because it was a Sanyo and the top wasn't popped but then I looked closer and noticed that the bung was pushed out. I replaced that but the back light still didn't work. Fuse F1 on the inverter board tested good.

I found a second working monitor and started comparing parts. Q2 7627 on the bad inverter was the closest to the bad cap so I tried that first. The Atlas DCA55 was unable to identify it 'Unknown/Faulty component' so it is not a standard transistor or FET. Thinking that I may not be testing these tiny SMD components right I pull Q9 J7 and find that it is an NPN transistor. The Q2 7627 on the good inverter tested exactly the same 'Unknown/Faulty component'. Comparing voltages I see:

Bad board:
Q2 Pin 1: 0V (connects to Q4 8637 Pin 3)
Q2 Pin 2: 12v (connects to capacitor and 12v rail)
Q2 Pin 3: 0.18v-0.34v (connects to PWM)

Good board:
Q2 Pin 1: 11.2V
Q2 Pin 2: Same
Q2 Pin 3: Same

I switch Q2 and the bad board works, the good board fails so Q2 is it. Now how do I get one? As I look around the board I see that semiconductor SOT-23 labeling is abysmal compared to similar size capacitors and resistors.

D1: C304t C3/04/t
D2: C304t C3/04/t
Q1: 9435A (delta)13GA
Q2: 7627 76/27 (paired with Q4)
Q3: L7 (paired with Q7)
Q4: 8637 86/37 (paired with Q2)
Q5: DKQH H-Bar (paired with Q6)
Q6: DKQH H-Bar (paired with Q5)
Q7: M6 (paired with Q3)
Q8: 9435A (delta)13GA
Q9: L7 (paired with Q12)
Q10: DKQH H-Bar (paired with Q11)
Q11: DKQH H-Bar (paired with Q10)
Q12: M6 (paired with Q9)
SD1: 310A 31/0A
SD2: 310A 31/0A

To make matters worse a few are different on the other board.

Q3: L6
Q7: M7
Q9: L6
Q12: M7

I see SMT identification charts but they aren't helping.

[severach]

Re: Compaq TFT5010 rack mount monitor

The two best SMD code translators I found were CliveTEC SMD marking codes and TKB SMD Database. From these I was able to figure out many components including Q2-76 that I broke. On the resistance scale the good Q2-76 measures 45K+22K = 67K from base to emitter and the bad Q2-76 measures open from base to emitter.

I bought an inverter board on eBay hoping to solve my problems. The board didn't work. I fixed fuse F1 and it still didn't work. I stole Q2-76 and got my original board working so I know that transistor works. No semiconductor shorts and transformers are fine. Q3-L7, Q7-M6, Q9-L7, Q12-M6, Q11-DK tested fine. After swapping Q2-76 too many times a terminal split so I decided that swapping SMT parts doesn't work for long.

So I diagrammed the circuit to eliminate the guesswork.

Looks like Q2 and Q4 form a power on circuit for the TL1451. Easy to diagnose and easy to jumper when replacement parts are not readily available.

The backlight flashes for half a second and T1 isn't putting out anything. I fix a bad connection I caused on Q7-M6 and now it works but does not dim even though the 2IN+ voltage changes from 0.95v to 1.33v. Maybe I messed up a SMT cap desoldering them to get the values or maybe that part of the TL1451 is burned out. I don't need dimming.

They'll both work when I get the replacements for Q2-76 DTA144WKA.

[PlainBill]

Re: Compaq TFT5010 rack mount monitor

I have a Compaq TFT5010 with no backlight. There was a bad cap SMD 100uf 16v C160 on the video board but that may not have been the problem since the Compaq logo was visible on the unlit display. All the 100uf 16v SMD caps on the video board show poor ESR. There was a bad cap Sanyo 100uf 25v C23 on the inverter. At first I ignored it because it was a Sanyo and the top wasn't popped but then I looked closer and noticed that the bung was pushed out. I replaced that but the back light still didn't work. Fuse F1 on the inverter board tested good.

I found a second working monitor and started comparing parts. Q2 7627 on the bad inverter was the closest to the bad cap so I tried that first. The Atlas DCA55 was unable to identify it 'Unknown/Faulty component' so it is not a standard transistor or FET. Thinking that I may not be testing these tiny SMD components right I pull Q9 J7 and find that it is an NPN transistor. The Q2 7627 on the good inverter tested exactly the same 'Unknown/Faulty component'. Comparing voltages I see:

Bad board:
Q2 Pin 1: 0V (connects to Q4 8637 Pin 3)
Q2 Pin 2: 12v (connects to capacitor and 12v rail)
Q2 Pin 3: 0.18v-0.34v (connects to PWM)

Good board:
Q2 Pin 1: 11.2V
Q2 Pin 2: Same
Q2 Pin 3: Same

I switch Q2 and the bad board works, the good board fails so Q2 is it. Now how do I get one? As I look around the board I see that semiconductor SOT-23 labeling is abysmal compared to similar size capacitors and resistors.

D1: C304t C3/04/t
D2: C304t C3/04/t
Q1: 9435A (delta)13GA
Q2: 7627 76/27 (paired with Q4)
Q3: L7 (paired with Q7)
Q4: 8637 86/37 (paired with Q2)
Q5: DKQH H-Bar (paired with Q6)
Q6: DKQH H-Bar (paired with Q5)
Q7: M6 (paired with Q3)
Q8: 9435A (delta)13GA
Q9: L7 (paired with Q12)
Q10: DKQH H-Bar (paired with Q11)
Q11: DKQH H-Bar (paired with Q10)
Q12: M6 (paired with Q9)
SD1: 310A 31/0A
SD2: 310A 31/0A

To make matters worse a few are different on the other board.

Q3: L6
Q7: M7
Q9: L6
Q12: M7

I see SMT identification charts but they aren't helping.

I'm hoping you can shed a glimmer of hope on a problem on a Sceptre monitor. I've found the cause of the problem (bad solder joint on a cap) and the components it killed (two SMD transistors). I'm running into a problem identifying the transistors. The inverter circuit itself is very similar (identical?) to the drawing you made. I'm having difficulty identifying the transistors Q5, Q6, Q10, Q11 marked with DKQH. Do you have any suggestions on identifying the manufacturer, or even the designation of the package?

PlainBill

[severach]

Re: Compaq TFT5010 rack mount monitor

Compaq TFT5010 1024x768
Panel: LG Philips LM151X2 (C2TH)
Power Supply: 12vDC 5A 4 pin Power DIN KPP-4P
Power Interface Board 60mm x 75mm: Optoma TFT5010 00.56/03.001 Rev:A 2SK8050S SK8050S KPJX-PM-4S
Video Board 175mm x 117mm: Optoma 00.56706.001 TFT5010 M/B Rev:A DVI Pixelworks PW111-10Q AD9886KS-100 Sil141CT80
Button Board: Optoma TFT5010 00.56702.001 Rev:A
Inverter 40mm x 150mm: Optoma INV-154 00.56704.001 TL1451A Transformer GCI EPC19N998-C024

The Power DIN connector is the same shape as the common 4 pin connector for an external hard drive but is not compatible. The wide pins are independent 12v sources and the narrow pins are independent grounds. The power board has traces and parts for a 15 pin VGA connector not present and the case has a punch out. The video board has a DVI input that does not accept DVI signals. It only accepts VGA signals through the VGA pins of the DVI connector. The stock VGA to DVI cable and a VGA to DVI adapter work. The dimming circuit seems to work on both boards. The brightness doesn't change much from 0 to 100.

This inverter circuit is almost the same as the inverter in the TL1451ACN based Dell E172FP E172FPb E173FP E173FPb. The transistors are labeled in the Dell service manual. DK are in the same position as NPN 2SC5706 and 2SC5707 on the infamous BenQ boards.

The last letters must be a production date code. I have 3 INV-154 inverters and the last letters are all different.

DKQH DKQG DKQF DK QH DK QG DK QF

According to the charts
DK BCX42 Sie N SOT23 gp audio pnp 125V comp BCX41
Where Sie == Infineon and "pnp" is a misprint. The Atlas DCA55 and the type column show that it is an NPN.

The new Rohm DTA144WKA parts are in and labeled 76 just like the old ones. Two parts in, two boards working.

I didn't have the original supply so I had to hack 12v in from another transformer.

[Scenic]

Re: Compaq TFT5010 rack mount monitor

^ those Elna's in the second pic are pushing their bungs out.

[PlainBill]

Re: Compaq TFT5010 rack mount monitor

Compaq TFT5010 1024x768
Panel: LG Philips LM151X2 (C2TH)
Power Supply: 12vDC 5A 4 pin Power DIN KPP-4P
Power Interface Board 60mm x 75mm: Optoma TFT5010 00.56/03.001 Rev:A 2SK8050S SK8050S KPJX-PM-4S
Video Board 175mm x 117mm: Optoma 00.56706.001 TFT5010 M/B Rev:A DVI Pixelworks PW111-10Q AD9886KS-100 Sil141CT80
Button Board: Optoma TFT5010 00.56702.001 Rev:A
Inverter 40mm x 150mm: Optoma INV-154 00.56704.001 TL1451A Transformer GCI EPC19N998-C024

The Power DIN connector is the same shape as the common 4 pin connector for an external hard drive but is not compatible. The wide pins are independent 12v sources and the narrow pins are independent grounds. The power board has traces and parts for a 15 pin VGA connector not present and the case has a punch out. The video board has a DVI input that does not accept DVI signals. It only accepts VGA signals through the VGA pins of the DVI connector. The stock VGA to DVI cable and a VGA to DVI adapter work. The dimming circuit seems to work on both boards. The brightness doesn't change much from 0 to 100.

This inverter circuit is almost the same as the inverter in the TL1451ACN based Dell E172FP E172FPb E173FP E173FPb. The transistors are labeled in the Dell service manual. DK are in the same position as NPN 2SC5706 and 2SC5707 on the infamous BenQ boards.

The last letters must be a production date code. I have 3 INV-154 inverters and the last letters are all different.

DKQH DKQG DKQF DK QH DK QG DK QF

According to the charts
DK BCX42 Sie N SOT23 gp audio pnp 125V comp BCX41
Where Sie == Infineon and "pnp" is a misprint. The Atlas DCA55 and the type column show that it is an NPN.

The new Rohm DTA144WKA parts are in and labeled 76 just like the old ones. Two parts in, two boards working.

I didn't have the original supply so I had to hack 12v in from another transformer.

Those transistors are Rohm 2SC4672. DK is Rohm's designation for that transistor, Q specifies the high gain range (P would be the low gain parts). I believe the last letter is a lot or date designation. Of course, the part may be available from other manufacturers.

PlainBill

[severach]

Re: Compaq TFT5010 rack mount monitor

^ those Elna's in the second pic are pushing their bungs out.

They don't look like it to me even in the picture and they wern't in RL. The brown stuff under the caps is glue.