25) ibm 수리내역

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QUESTION NO. P70703-4:  IBM 6556-03N monitor Sony chassis SCC-LO7G-A   raster is tearing top 1/3 of screen, improves as it warms up.  Worse in high resolution modes.

Check C575; also check C573, since the problem is worse in certain modes.

QUESTION NO. P41703-7:  IBM 6558-03n monitor (Sony scc-l04h-a) shuts down deflection code.  Need part # or ic # for ic 702(vertical) which is missing.

The Sony schematic shows IC702 is LA7841L also check R720 1R 1/2W flame proof resistor and R727 1R 1/2W Flame proof resistor.

QUESTION NO. P101702-6:  IBM 6547-0BN monitor has a faulty HOT SEC5088.  Could not find any other faulty components, but when I replaced it, the transistor promptly blew again, what other components could be responsible?

What replacement did you use for your SEC5088?  Proper number for replacement is KSC5088.  2SC5088 is not equivalent.

QUESTION NO. P100302-2:  IBM 6558-03/U monitor made by Sony displays only lower half which shakes or is very wavy.  Changed vertical IC, did not help.

The common cause of such symptoms in the Sony N3 chassis is a defective IC007, CXA2043Q, Sony p/n# 8-752-078-46.

QUESTION NO. P80502-9:  IBM 6547-0BN monitor.  I am looking for info and possible replacement and/or datasheet for a HOT marked "SEC C5088".

"SEC C5088" stands for Samsung Electronics Corporation 2SC5088 which many electronic supply stores can carry.

This device is KSC5088, formerly made by Samsung Electric Co. (SEC).  It is rated 1500 Vcbo, 800 Vceo, 8 Amps (15 Amp surge), 50 Watts, Tstg < 3 usec, Tfall < 0.2 usec, no internal damper diode. Possible substitutes include NTE2324, 2SC4923, 2SC49244, 2SC5299.

QUESTION NO. P62702-1:  IBM 6543-303 (G50) monitor, in mode 640 X 480 works fine, but in dos mode the vertical raster is reduced 50%.

Check the system control processor ST6370.

QUESTION NO. P40902-8:  IBM G74 monitor.  Photo transistor OP601 PC123 (made by Sharp) and video driver LM2405T burnt.  What is a reasonable substitute for PC123?

The Sharp PC123 optocoupler resembles an NEC PS2501-1.  This NEC device is listed by Mouser (www.mouser.com) and Digikey Corp (www.digikey.com), among others.

QUESTION NO. P116-9:  IBM G74 monitor.  Opto coupler OP601 PC123 (made by Sharp) and video driver LM2405T burnt.  What is a reasonable substitution for PC123 opto coupler?

A reasonable substitute for the Sharp PC123 is the NEC type PS2501, which is carried by Mouser Electronics (www.mouser.com) and Digikey Corp. (www.digikey.com).

QUESTION NO. P823-9:  IBM 7095-593 monitor with a pincushion problem.  I replaced the 47 Ufd cap near the flyback and also the vertical IC.

First check C539.  If that is not the cause, try checking IC501 (either STV7778 or TDA9103).

QUESTION NO. P411-4:  IBM 2124-001 monitor.  I need a value for c335, c336 and r214.

This IBM is similar to the Acer 7154e chassis. C335 = 220 pF/2KV, C336 = 0.01 uF/50V, and R214 = 15K ohms.

QUESTION NO. P10604-9:  IBM 6547 monitor, transistor KSC 5088 Blown & IRFI 6530 .  I replaced them & they blew again.

If you are not able to ring the flyback, unplug and short the tube top cap to the aquadag. Now measure resistance to chassis from top cap, any reading is bad news. Can also test for capacitance, nano farad OK  15 to 25 pF bad news.

QUESTION NO. P320-2:  IBM 6555-773 monitor has overdriving G2.  It is just raster no video.

Once again, the likely problem in this GDM20E03 chassis is IC420, which controls both the G2 levels and video signals.

QUESTION NO. P320-1:  IBM 6555-773 monitor has no video when turned on. I adjusted the brightness button , but nothing happens.  However, I can see in the dark the display for brightness is up to 100% already.

The FCC# for this IBM model indicates that it is a Sony GDM20E03 chassis, and it suffers from the same faults as that chassis (listed elsewhere on this page).  The common problem is IC420 = CXA1907S (Sony p/n# 8-752-071-56). This IC controls both G2 and RGB video. If pin#22 of IC420 is too low, G2 voltage will be too low.  If the fault is low or no filament voltage, check C677 and C683.

QUESTION NO. P121-9:  IBM 8513001 monitor.  I need values for R806.

Iif R806 is from the power supply then its value is 370 ohms at .25watts.

QUESTION NO. P116-9:  IBM 2124 -001 monitor, manuf. date dec.97, it has a Samsung CRT (mod# M36KUQ35X92) (SKD).  The part # of the main PCB is 55.78520.001.  I need the value of C335 on the main PCB or any useful info in identifying or cross referencing (the cap is burnt beyond recognition).

This chassis is similar to the Acer 7154e. C335 is a 220 pF/2KV ceramic disk capacitor, but is better replaced with a 3KV rating. Mouser (www.mouser.com) carries such caps.

QUESTION NO. P1027-10:  IBM 6544-403 monitor has raster but no video.  However, when powering down video is momentarily present.  Replaced LM1205 on CRT pcb-same.

On this G70 model, when there is no video with the signal cable still attached, but the picture flashes on the screen during shut-off, the usual cause is a bad rubberized-membrane control panel (under the CRT face), which must be replaced.

QUESTION NO. P921-2:  IBM 6324 monitor has burned resistor R321causing it to appear dead when a video signal is applied.  Need the value of the resistor, and possible causes why it may have burned.  There is a 47 mf 50v cap attached to one lead - tested good. The resistor is located near Philips IC TDA4852 that I have been unable to cross.

R321 is 100 ohms.  Check if zener CR310 is defective, or if vertical IC Z302 = TDA8351 is shorted; or if the supply voltage to pin#6 of Z302 exceeds 50V.  The TDA4852 is a Philips Horizontal & Vertical Deflection Controller IC.

QUESTION NO. P821-6:  IBM 7097-593 monitor Sept '96.  Q607 shorted (Nec J449).  I need replacement part # or Equivalent ECG number.

2SJ449 is a 250 Volt, P-channel MOSFET, and it has no ECG replacement.   Use either the original 2SJ449, or else use 2SJ307.  B&D Enterprises (800-458-6053; www.bdent.com) lists these two P-FET's, but if you cannot get either, an IRFI9630 might squeak by.  However, since that one is only rated for 200 Volts, it is not a recommended substitute.  Also, check out HOT Q602, R182 = 10 ohm/2W, and just replace C182 = 10 uF/250V.

QUESTION NO. P726-7:  IBM 2124 monitor had a blown Q310.   After replacing, the monitor and the HV came on long enough for me to see R214 fry.   I traced this to a bad c335 and replaced both.  I could not find a 2KV cap, so I used a 6KV.  Now the monitor powers up, but no HV even after replacing d316 (d317 was OK).

If R214 has fried, it seems likely that the overvoltage also damaged IC201 = TDA4858, so check or replace that IC. Also check out regulator FET Q317, and see if coil L304 looks burnt, rings bad, or has dropped below 0.5 mH inductance (nominally "2 mH", but an inductance of at least 0.7 mH probably is OK). For C335, a source for these 2KV and 3KV (preferred) 220 pF ceramic caps is Mouser Electronics (800-346-6873; www.mouser.com).   If there are width/pin problems after power-up, but L304 is OK, then check out Q302 and Q303.

QUESTION NO. P425-3:  IBM 2124 monitor.  Front indicator flashes about three times per second.  Black/blank screen.  Ticking sound from transformer in front of Q602 coincides with front led flashing.  Replaced Q602 and IC601, checked diodes on P.S. area.  Still same.

Check FET Q317 (IRFI630 or similar) for leaky/shorted; also check D316 and D317.  If the FET is bad, also check if coil L304 got cooked, and check if it still retains at least 0.5 mH of inductance (0.8 to 2 mH is nominal), or else your new FET may also die.  Also check HOT Q310, disk cap C335 = 220 pF/2KV, and R214 = 15K ohm.   A bad C335 can cause any of these components to die, so replace C335 if you have even the slightest suspicion; it can test good when it is not.

QUESTION NO. P327-4:  IBM 2124 monitor with the HOT S/C.   Replacing the device returns the monitor to service for a couple of minutes before getting very hot and blowing the transistor again.  There is no evidence of HT issues when the monitor is on, as the picture is very good.

Whenever the HOT blows, check C335 = 220 pF/2KV disk cap off the HOT collector, and R214 = 15K, 1/8W, in line with C335.  Replace C335 on even the slightest suspicion, it often seems OK when it is not. Also check C319, D316, D317, MOSFET Q317, coil L304 (probably damaged if burnt, or if it measures under 0.5 mH), and IC201 = TDA4858.  Check the solder in the horizontal area, and around the diodes in the secondary of the power supply.  Finally, ring the flyback.

QUESTION NO. P218-3:  IBM G70 monitor, when powerd up the led blinks green/orange.  The high voltage comes up but there is no picture.  With or without video signal the problem is the same.  Already replaced processor and keyboard assembly for no good.  What does the blinking led means (I believe the processor senses a fault condition somewhere)?

Sounds like a video card problem.  Try swapping known to be good card with old card and also try switching slots.

QUESTION NO. P126-1:  IBM 9527 monitor displays only a vertical line.

Failure of the horizontal deflection circuitry, or open horizontal yoke.  Check transistors T32 and T48, and their associated components (B+ line resistors, B+ regulator FETs, inductor M3, etc). Check generally for bad solder connections.

QUESTION NO. P123-1:  IBM P70 6554-603 monitor, Sony chassis - FCC id AK8GDM17ER01, fails to start.  When turned ON, the power indicator LED is green then turns orange (or cycling green/orange if the monitor is connected to the CPU) after about 5 seconds.  During the 5-sec LED "green" time, dc supply voltages of 180v, 75v, +/-15v and 22v are present at connector CN640.  Also during this time 12.7v supply is present at SMPS IC601. All aforementioned voltages disappear after the monitor shuts down ("orange" LED time).  CRT filament is momentarily lit, and the usual high voltage crackle and half-second bright flash at the back of the CRT is observed during this 5-second start-up time.  These other supply voltages were also observed 6v at connector CN671, and +/-15v, 5v at CN670.

Try to change the tda  (ic) controls the horizontal and vertical and the B+ and you have the protection circuit controlled by this one.  Good chance.

QUESTION NO. P1124-8:  IBM 2124/Acer 7154E monitor came in with shorted HOT.  Replaced that & c335 220p/2kv, r214/15k. still no HV start. 48v on collector of HOT, Q316 * 317 OK. deflection IC TDA4858 warm to touch.

The most probable culprit is a shorted coil L304, p/n#19.40133.001. It's best to ring it, but if you cannot, and it's testing below its 2 mH inductance, or it appears at all discolored or burnt, or it runs very warm, replace it. Also check D316 and D317. Note, sometimes, the diodes & transistors in this unit will not test out as shorted, and yet still have high reverse leakage, so be aware of this.

QUESTION NO. P1118-9:  I need the cross for a ZTX 948 transistor for an IBM G50 monitor.

Believe it or not, that little ZTX948 PNP transistor is rated for over 5 Amps!  Do not use a cross, get the original. If you do not have a local supplier for Zetex Super E-line transistors, try B&D Enterprises (800-458-6053, www.bdent.com) or Digi-key (800-344-4539, www.digikey.com), who both list ZTX948 in their stocks.

QUESTION NO. P114-10:  Two IBM 7097-5C3 monitors ans serial # 2304066.  Q602 (C5442A) and Q607 (J449) shorted and R182 (I think it is 10 ohm 2 watt) was open. Replaced all, and set came up for about 20 seconds, then Q607shorted out again. Can make high voltage function by substituting B+ and base drive on Q602 with Sencore HA2500. With FBT isolated from B+, voltages on Q607 seem awfully high (around 200 volts).  What should these voltages be, and what could be wiping out Q607?   Also, what is the value R182?

Whenever Q602, Q607, and R182 are bad, C182 = 10 uF/250V must also be checked or replaced, it gets bad ESR and causes excess power dissipation. R182 = 10 ohm/2W.

QUESTION NO. P1018-3:  Several IBM G50 6543-301 monitors that are dead.  When turned on, they make a high pitch grumble.  I suspect the flybacks are bad. I cannot locate replacements. It is a Sampo FEA-426.

Possible sources might be Component Technologies (888-359-2225), ICM (800-748-6232), Cactus Technology (626-357-7979), or Sampo itself, (770-449-6220). In Europe, try ICHE (UK), or AGEA Technologies (France). Or, for a substitute, HR Diemen (www.hrdiemen.es),  email (HR@hrdiemen.es), lists their transformer# HR7933 as an equivalent to FEA426.  Other components implicated in "dead" G50's are, capacitors C162 & C164; the AC bridge rectifer (BR66) and the two 1.5 ohm resistors beside it; R507 = 470 ohms & R523 = 1 ohm near the flyback; Q520 = ZTX948, Q521 = ON4873, Q522 = BUZ11A; the Z200 uProc.; and the front panel keypad.

QUESTION NO. P108-2:  IBM 6321-001 monitor. When powered on it emits a pulsing squealing sound every second or so. There does not appear to be any high voltage. The power light does not appear to come on. I have checked most of the diodes / transistors in the main power circuit. I also checked the HOT on a whim. The HOT seems to have some funny readings.

It did turn out to be the HOT transistor that was blown. I have since replaced it and the monitor is now repaired.

QUESTION NO. P101-2:  IBM 2124 monitor.  When switched on, sometimes a display is shown on the screen.  I checked for bad contacts.  The led on the front is green all the time.

Replace ceramic disk cap C335 = 220pF/2KV (it is better to use a 3KV-rated cap), also check the in-series resistor R214 = 15K ohm for damage. Do this soon, before this cap causes your HOT to short out. After replacing C335, run the monitor awhile at a faster scan rate (like 54 KHz), and then check if the new cap has been overheating.   If it is overheating, the replacement cap is not of sufficiently high quality.

QUESTION NO. P923-10:  IBM 6317-001 monitor with vertical problem.   The picture only moves from the bottom not from the top,whereas it should move from the both ends by using the vertical controls.  If the vertical button is pressed to open the picture, it starts shrinking the picture and work opposite of its function.

Try checking capacitor C311 = 10 uF/100V, near the flyback.

QUESTION NO. P910-1:  IBM 8517 monitor works for a while then shuts down.  When I turn it off, wait a few minutes turn it back on it would come back on. Did this for awhile, now it will not come on. High voltage just starts up then the high voltage goes down. Changed a few caps in the power supply. Sounds like the monitor is going into shutdown.

Check whether D503 (SMD zener, 9.1 Volt) has gone bad. If bad, replace with either an SMD or thru-hole type zener; zener voltage ratings from 9.1 to 12 Volts should work OK as replacements.

QUESTION NO. P92-10:  IBM 9527011 monitor.  We have replaced R143 which was open, as well as T26, T32, and T47. T26 showed signs of excessive heat. We have B+ voltage (160V) but it does not appear to be making it to or through the horizontal circuitry. The B+ is making it to C96.

If you check the FCC number, you will see that this is a Nokia chassis. Check that those FET's are getting good gate pulses. Also, inductor M3 can cook and short between windings, so check out M3. You may need to change the TDA4852 on the microprocessor board. This Nokia has the same problems that other Nokia chassis have (bad solder, bad SMD's, etc); see more details in Monitor Repair Answer# P826-1.

QUESTION NO. P823-10:  IBM 6543-301 monitor (G50), dead.  I have a 45vdc in the hot.  In the power supply I have 166vdc.  I changed IC tda4855 and tda4866 with no change. Also, what is the IC ST6370J5B1/BLI.for this?

If the unit is 'dead', check Q520, Q521, Q522, Q603, R102 & R145 = 1.5 ohm, R133 = 0.15 ohm, R424 = 180K, R520 & R521 = 22 ohm, R523 = 1 ohm, the bridge, CR113 = BR66, CR502 = BYV27, and check caps C162 = 470uF/25V and C164 = 1000uF/25V for value and ESR. These two capacitors, when marginal or bad, can cause a host of problems. That voltage of 45 VDC is too low. It could be there's a fault in the voltage boost circuit run by FET Q602, if the FET does not operate. It would be unusual (though not unheard of), for a FET to fail as nonfunctional, rather than shorted, so see if the FET's gate is getting good drive pulses. If not, my suspicion would be to ring coil L600, in series with the FET, for shorted turn(s), that would cause an overcurrent-related shutdown of the driver IC, Z600. But, there's a possibility that the driver IC could be dead, or that it's not receiving its 12V supply (at pin#7). The preprogrammed microprocessor IC, ST6370J5B1/BL, is an expensive and hard to find IC, that, when it goes bad, can cause shutdown problems.

QUESTION NO. P720-3:  IBM G41 monitor with two transistors that I need a cross ref for; ssh5n90 and Dn or ON-4873.

SSH5N90 is a Samsung FET, TO3P case, 900 Volts, 5 Amp, 150 Watt. A possible cross would be 2SK1358, or maybe 2SK872, available from MCM (800-543-4330), B&D Enterprises (800-458-6053), etc. ON4873 is a Philips HOT, and LJ Enterprises (800-627-8755) has carried this OEM HOT. It is never a great idea to try to sub a HOT, and that's also true here, but if you get stuck, try a Philips BU2520.

QUESTION NO. P716-8:  IBM 6543-301 monitor.  When turned on, it turns the high voltage on and there was a picture in about 5 seconds but, after turning it on and off 20 times at does not even start the high voltage any more.

First check/replace C162 & C164 in the power supply. These capacitors can cause problems when marginal, and eventually can kill other parts, so also check resistors R424, R507, R520, R521, R523; transistors Q520, Q521, Q522, and Q600; and diode CR502.  If none of these parts are faulty, the bad news is that the CPU IC, Z200 = ST6370J, also commonly marked "IBM PLUTO", is a common and expensive failure item for shutdowns in this chassis.

QUESTION NO. P716-2:  IBM-2124 (FCC JVP7154E) monitor also known as Acerview 7154.  Need replacement for L304 2mH measured at 768uH and a source.

Try a Mitsubishi, or an Acer (FCC#JVP) supplier, part number 19.40133.001 is L304. In the US, Gastron Technology (626-813-1503), ICM (800-445-1503), and Marcus & Assoc. (800-445-1503), among others, have carried Acer parts.

QUESTION NO. P77-2:  IBM 2124 monitor. The horizontal output Xister was S/C. Replaced ok. When fired up a small disc ceramic cap off the Collector of the H/output Xister was s/c. This caused a resistor connected to the cap to burn open. I measured the B+ at voltage a the H/out collector and only had 50 DC.  Also no base drive to the H/output.  What is the value and working voltage of the disc ceramic cap?  What is the vaule of the 1/8 watt resistor connected to the cap?  What should the B+ voltage be at the Collector of the H/output?  Where is this voltage fed from?+?

If the FCC# on this IBM is JVP7154E, then the ceramic cap is C335 = 220pF/2KV, the resistor R214 = 15K ohm. In VGA mode, expect the B+ at the HOT collector to be around 78 VDC, with 1200 Volts peak-to-peak. The FET for B+ regulation is mounted on the same heatsink as the HOT, but check out both Q316 and Q317, also coils L304 and L305 and assoc. components.

QUESTION NO. P68-2:  IBM 6542-103 (G40) 14" Monitor is unbearably fuzzy.  External controls (contrast & brightness) have only slight effects. Have been unable to find schematics. Have found Vertical/Horizontal hold.   Hoping to find focus.

Focus control is located on the side of the flyback. However, if the focus adjust also raises and lowers the raster you have a bad flyback and it will need to be replaced.

QUESTION NO. P622-3:  10 IBM G41 6542-301 Monitors, all have problems.  Where can I find service information on these?

Try M. I. Technologies, www.mitechnologies.com (document 2884-L).

QUESTION NO. P526-10:  IBM 6543-301 monitor (G50) with no high voltage in the hot.  There is 45vdc and 45vdc in the neck board.  When I start the monitor the led blanking "green orange".  I changed the IC number tda4855 and tda4866 with no change.  Also, what is the pin out for IC ST6370J5B1/BLI.

Is there B+ at the collector of the h output or B+ terminal of the flyback? Is there B+ at the collector of the h driver transistor, do you have any HV at initial startup or does the unit totally refuse to produce any eht? What value is the regulated B+ from the smps? It should measure roughly 125 - 130 volts. If there is no source to the deflection ckts then look for probs in the regulator/smps.

QUESTION NO. P412-2:  IBM  6543-305 (G50) monitor, dead.   After replacing LM393 in power supply, the monitor works, but the bright control key does not.  The other control keys are working.

Check R424, near the flyback, for value or open. If R424 is OK, see if that fragile ribbon cable assembly going to the user controls has broken, and needs replacing.

QUESTION NO. P45-10:  IBM G70 monitor  6544--403.  I need a part # cross for Q872.  The part is marked FQ161 replacing to fix green screen.

If Q872 has a TO-92 case, this is probably a Philips BFQ161, NPN video transistor, rated 19 Vceo, 0.5 Amp, 1 Watt, Ft  >1 GHz; there is no ideal cross for this device.  Arrow Electronics (800-833-3557) lists BFQ161 in its inventory, or you might try a Philips distributor, but the device is obsolescent.

QUESTION NO. P225-2:  IBM 6540-00N monitor. No screen, LED is on, have high voltage(25Kv), tube neck doesn't light up, 0v at heater. Capacitor between the two heater lines says 223Z on it, What value is this? (223pF?)

The value is 0.022 uF. See the answer to question# P216-2, on the TV repairs answer page, for the details on reading these capacitors.

QUESTION NO. P129-7:  IBM  9527 17P Monitor.  It looks like regulation trouble.When you turn on the monitor It is very dim.Turning up the screen control,causes a wide fluctuation in the screen size.  Almost invariably a cap in switched mode?  Closed architecture of course.  Cannot get any schematics from ICM,or IBM.

It's time tp polish off those trouble shooting skills. Is the switch-mode voltage changing?  You may have a bad FET on the input to the flyback.   Of course you could have a bad flyback or even a shorted crt.

QUESTION NO. P1210-4:   IBM G70 6644-433 monitor. Horizontal width jumps from normal full screen to full screen minus 1" on each side. Left most push buttton (\\ >.<) restores screen to full. This happens at approximately 5 to 10 minute intervals. I suspect that the microprocesser is the culprit, but would like another opinion before I spend the $40.

I have seen two IBM G70 monitors with similar problems. The buttons seem to drift on their own. Cleaning the ribbon cable contacts on the mylar button strip fixed one but the other needed a new mylar button strip. To test this, set the controls and then disconnect the strip. The monitor stayed stable this time. One monitor had the horizontal problem and the other had a standby problem as well as the screen would lose blue over a few minutes (this one was fixed by cleaning the contacts).

QUESTION NO. P1027-6:  I have an IBM G70 and need the value of R101.  Also, R101 and CR105 were replaced. CR105 shorted R101 open. I tried a .57 ohm and it works somewhat. when plugged in, it comes up and stays. when unplugged and replugged in, R101 pops and opens. I can also hear faint ticking sound. HOT ok . When monitor comes up first time, it functions fine.

R101 is a 0.33 ohm fusible-type resistor.

QUESTION NO. P107-3:  I have an IBM 8517 SVGA Monitor with no high voltage.   The green led comes on.  I replaced shorted mosfet, shorted horizontal outbut transistor, and an open  device (P5502).  I assumed the open device was a fusible resistor.  I did not know the value of the component so I replaced with a 1.6amp fast-acting fuse.  When powered up, a blank screen and heard the usual static crackle associated with high voltage upon turn off.  During one power up, the new HOT shorts and causes power transformer to squeal.  The yokes test OK.   I think the flyback is OK.  What's up?

The ITC is bad.

QUESTION NO. P1027-8:  I have an IBM 14" monitor that will not sync properly.  It is labelled 2248 on the front and has type 96G0134 written on the back.  Can you confirm‎ for me that this is a VGA or SVGA monitor and not a XGA monitor?  If it is an SVGA monitor,  do you have any tips on what might be wrong with it?

I have looked through IBM for that model number and cannot find it.   Chances are it is a fixed frequency monitor. If you recheck the numbers on the monitor you cam go to RESTORSTONE at http//www.restorstone.com/monitormanu/searchmainint.html or GRIFFIN at Http//www.nashville.net/~griffin/monitor.html.

QUESTION NO. P921-8:  I have an IBM 8512-003 VGA monitor that has a high pitch sound coming from the power supply. The picture is wavy, but is still very clear. Could anyone help me with a remedy to this problem?

First, replace C120 = 10 uF in the power supply, use a 105캜 cap if you can. Also check fast recovery rectifier CR105, and, near the flyback, 3 Amp, 600 Volt rectifier CR212.

QUESTION NO. P925-5:  We have several IBM G50 and G41 that have HV problems. The HV leaking from the FBT. First we suspect the FBT itself but we are not sure. It could be that the HV is too high. The picture is OK.

Reading your question states that hv is leaking from the fbk. This would indicate to me that the insulation of the fbt is breaking down causing a path to neutral for the hv. Only cure that I have found that works is to replace the fbt assemblies. You may try applying a sealant to the fbt but I will bet it will not stop the short.

QUESTION NO. P98-5:  Tenemos un monitor IBM 6543-302 con insuficiente e incontrolable anchura horizontal, estando a la vez fuera de frecuencia.  풮odeis ayudarnos?

La averia que tiene ese monitor es muy comun tienes un condesador electrolitico seco, normalmente llevan tres condensadores cerca de la deflexion horizontal cambialos los tres y ya esta. Para encontrarlos sigue los cables del yugo de deflexion de horizontal.

QUESTION NO. P729-4:  I am wondering why the damper diode of the IBM G70 monitor keeps shorting. A new diode (BY359F 1500) will bring it back to life, but only for a few minutes. The diode shorts, the power supply stops.  Could you tell me what the original diode for cr301 should be?  IBM G70 model 6544-403 part number 96G1870 FCC ID AN06544.

Diode must be at least 2A 1000V.  Any diode less than that will blow.

QUESTION NO. P81-7:  I have an IBM 8513 that blew the HOT transistor after making a buzzing noise. When I replaced the transistor, the monitor has HT voltage but no longer has any vertical deflection.

Prob the vertical output ic and associated rectifier and protect resistor{s}. Prob the ic failed causing an overload which is what caused the ps to buzz in agony before opening the fuse resistor.

Check all power rectifiers coming off the flyback. Perhaps there is a shorted one which powers the vertical outputs. There may be a fusable resistor in series with the rectifier. Also check the electrolytic capacitor on that line too, as well as the parts in the vertical circuit.

QUESTION NO. P720-9  MONITOR IBM 8515  I have replaced a fbt TLF71004D in the 8515-002 model and it worked correctly.  The same fbt on the 8515-022 and 8515-222 models do not work correctly.  Apparently the boards are the same, without difference.   I have tested more fbt and different models but without results!!   The fbt is not original, is a copy but works correctly on the 002 model !!   Both the model install a tlf71004d fbt.

You should test the tube, preferably with the Sencore beamrite 7000 which checks low level tracking. This test when it fails indicates a "leaky" tube which affects contrast and colors - NO way to fix this problem.

QUESTION NO. P325-10:  IBM G70 which is completely dead.  By probing at the SMPS I can see attempts to start but nothing happens. HOT measures ok.

Check the diode CR210 (can be replaced by BYV29-500). If it's ok, then check CR112, CR122 (can be replaced by 20V zener).  If replaced, both diodes must be replaced, and flyback-tranformer must be adjusted .  Also check Q101, Q102, R103 and R104.

Also check two resistor ( 3M3) near Q101 and Q102

QUESTION NO. P36-6: Tengo un monitor IBM mod 6322 con el siguiente problema, no hay deflexion vertical esto ocurrio despues de averiarse el teclado e verificado el circuito de vertical y en una de las patas del tda 8351 hay 45v 풽s normal? 퓁deas?

I have a monitor IBM mod 6322 with no vertical deflection due to damage to the keyboard. I checked the vertical circuit and in one of the legs of tda 8351 there is 45v. Is this normal? Ideas?

If you have TDA8351, a 9-pin device, then pin # 6 can have up to 50-60 Volts in normal operation, and 45 Volts is a typical value. Pin 6 is the input for the supply to the flyback switch. If instead you have TDA8351A, a 13-pin device, this input is at pin # 8. For more information on TDA8351, download the datasheet from http://207.87.19.21/acrobat/2083.pdf.

Si usted tiene TDA8351, un dispositivo de los 9-contactos, despu? un contacto # 6 pueden tener hasta 50-60 voltios en la operaci? normal, y 45 voltios son un valor t?ico. El contacto 6 es la entrada de informaci? para la fuente al interruptor del tiempo de retorno. Si en lugar de otro usted tiene TDA8351A, un dispositivo del 13-contacto, esta entrada de informaci? est?en el contacto # 8. Para m? informaci? sobre TDA8351, descargue el datasheet de http://207.87.19.21/acrobat/2083.pdf.

QUESTION NO. P219-6:  Three IBM 9518-001 monitors with problems in the vertical, there is no stable image.

The 95xx series monitors are XGA variety. Which translates to a special type needing a different drive signal, otherthan a std vga signal. Symptoms are loss of vertical and horiz sync.

QUESTION NO. P220-2:  IBM 8512-001,with problems in the vertical, there is no stable image. Change the resistances of adjustment, no results.

Verify that pin 14(Vert.Sig) from the cable end position to the chassis is not open. These IBM cables have been known to open very easily. Generaly kinks at the cabinet input area are common.

Check the capacitor that is across the vertical yoke pins on the mainboard.

QUESTION NO. P24-3:  Several IBM 8515-001 monitors all of which have a hole in the lopt. After replacing the lopt and checking the hot the unit starts and then goes into protection immediately and switches off, even the led goes out. It is not a short on the secondary of the psu. I have tested.the new lopt works in a working unit. The vertical ic appears to be ok.

Check for a bad capacitor to the rear of the board, near the lopt.

QUESTION NO. P23-3:  IBM 9517-001 monitor with a sync problem. It will sync at 640 x 480, but will not sync at any other frequency. The display appears to be shifted to the left, and when entering Win95, display goes completely off, and appears to be at the top of the screen. In other responses on this service, similar questions were answered the monitor being an XGA and not capable of VGA and SVGA. Is this monitor an XGA as well?

BM monitors with model numbers beginning with "95" are XGA monitors. These monitors are generally not compatible with VGA/SVGA systems.

QUESTION NO. P113-8: IBM model 5154 VGA, no raster, no green power LED. Before total failure it was having trouble displaying the first couple of characters on left hand side of the raster.The switching PSU is a modular plug in. I've pulled the horz transistor, it checks OK and does not solve the problem. Have replaced the main IC in the PSU, a SG 3542 switch mode control IC, and this does not solve problem either. Input caps and rectifiers SEEM to perform OK and produce a good 300 v D.C. One clue is the supply to the IC which is usually shown as 28 v D.C. in the data sheet is made from what appears to be some sort of complex boot strap circuit whose source is the big output transformer. Am I chasing my tail on this one ?

This sounds like a classic P.S. failure. Other P.S. that I've repaired had low valued caps in the current sensing curcit. I recall there were 3 electrolitics 10uf, 1uf. & 47uf(not sure). All were grouped together at the top of the board. I assume you have checked the MJE13005's for countinuty.

QUESTION NO. P19-2: IBM - 8514 monitor Diag - dead, fuse is okay.

Other symptoms would be helpful. As unsual noises squeals, humming. etc.Any LED indications. Two distinct problems come to mind. One is open/shorted HOT. The other is shorted low voltage cap on the video board, something like 100uf @50vdc.

QUESTION NO. P1211-2:  IBM model 9518-001 VGA monitor , on boot up the vertical sync is out and a loud squeal when windows starts the colors are blurred, as soon as program manager loads every thing is normal.

IBM 9518 is a XGA monitor. It will not work with VGA or SVGA mode.