Intermittent Pin Cushioning Problem - IBM 9527-011

[ricardo]

Hello To ALL,

ref: PC Monitor, IBM 9527-011; FCC ID IEY9527 (Nokia Chassis)

Symptoms is that image vertical left side has bow in to the centre
intermittently. Right side vertical OK. Image occasionally "twitching"
towards the centre and at times image unreadable while got "sqeezed" to
the centre. With computer shutdown and OFF, I power ON the monitor, the
raster(?) image shows the same pincushion (bowing inwards) problem and
twitching! ;-(( Control panel at front with pincushioning button
depressed does NOT restor but attempting to, meaning button is working.
A soft "whistling" sound heard whenever image in distress mode (twitchng).

I have the cover removed and the system board carrier (chassis?)
detached from CRT. The smaller processor board(video input + BNC
connectors) is under the main board. I am "staring" ;-)) at the circuit
boards not knowing where to look for the culprits ie caps, ic's,
resistors, dry joints etc. Visual check on all components (SMD's)is
clean and no sign of burnt mark. Don't have a schematic here. (...love
to have one or look up/download ?)

Any tips, hints, pointers is greatly appreciated. Thanks a million!

Regards,

....ricardo

 

[Jerry G.]

Do an ESR test of all the capacitors in the scan and pin sections. Change
all the caps that are out of specs. This will weed out all the bad caps to
start with. Being intermittent, it may be a bit complex to find, but you
may be lucky with the ESR test.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
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"ricardo" <rcrc7@netscape.net> wrote in message
news:BRnNb.103384$ts4.4684@pd7tw3no...
Hello To ALL,

ref: PC Monitor, IBM 9527-011; FCC ID IEY9527 (Nokia Chassis)

Symptoms is that image vertical left side has bow in to the centre
intermittently. Right side vertical OK. Image occasionally "twitching"
towards the centre and at times image unreadable while got "sqeezed" to
the centre. With computer shutdown and OFF, I power ON the monitor, the
raster(?) image shows the same pincushion (bowing inwards) problem and
twitching! ;-(( Control panel at front with pincushioning button
depressed does NOT restor but attempting to, meaning button is working.
A soft "whistling" sound heard whenever image in distress mode (twitchng).

I have the cover removed and the system board carrier (chassis?)
detached from CRT. The smaller processor board(video input + BNC
connectors) is under the main board. I am "staring" ;-)) at the circuit
boards not knowing where to look for the culprits ie caps, ic's,
resistors, dry joints etc. Visual check on all components (SMD's)is
clean and no sign of burnt mark. Don't have a schematic here. (...love
to have one or look up/download ?)

Any tips, hints, pointers is greatly appreciated. Thanks a million!

Regards,

....ricardo

 

[ricardo]

Jerry G. wrote:

Do an ESR test of all the capacitors in the scan and pin sections. Change
all the caps that are out of specs. This will weed out all the bad caps to
start with. Being intermittent, it may be a bit complex to find, but you
may be lucky with the ESR test.

Thank you for the advice. Will look into it when I got hold of a ESR

meter. Any idea where to find/buy a schematics for the above monitor? I
tried IBM, no luck there either.

Thanks,

....ricardo