Commodore 1084 monitor showing flyback / retrace lines.

[John]

I have just powered up the old monitor after it being packed away for a
few years. The top 1.3 of the screen is showing these lines. Is this a
common fault? Any pointers as to how I could repair it?

 

[AJ]

ESR the caps in the vertical deflection circuit, may find numerous ones due
to age of the monitor. Change any that check out of tolerance and change the
vertical output device.

 

[James Sweet]

ESR the caps in the vertical deflection circuit, may find numerous ones
due to age of the monitor. Change any that check out of tolerance and
change the vertical output device.

Why change the vertical output device? It's obviously working fine.

Second that on the capacitors, there will probably be one or two bad
electrolytics near the vertical output section.

 

[AJ]

Called prevenative maintanence, if the monitor is going into continual
service, the cost if the additional component is minimal with regard to is
probably failing in the future. FWIW, IMHO

 

[James Sweet]

Called prevenative maintanence, if the monitor is going into continual
service, the cost if the additional component is minimal with regard to is
probably failing in the future. FWIW, IMHO

Continual service? Of a Commodore monitor?

I've never heard of preventative replacement of semiconductors, capacitors
sure, lytics dry out, but semis don't automatically fail. By that logic, one
may as well replace the flyback, HOT, power supply chopper, heck the whole
monitor. If it ain't broke, don't "fix" it.

 

[John]

ESR the caps in the vertical deflection circuit, may find numerous ones
due to age of the monitor. Change any that check out of tolerance and
change the vertical output device.

Thanks for your feedback guys. However it's been so long since I've
poked around inside a monitor / TV that I am uncertain where to look.

Is the vertical section you refer to, the LOPT etc ?

I was considering looking on ebay for another one of these but if I
could resurrect this one, I would save a few pennies. However it is
possible, this unit may be on its way out. The brightness is up full, to
get a normal picture. When using separate chroma and luma inputs from
the C64 computer, colours still "interfere" with each other eg brown
text on a blue background is almost unreadable.

Anyhow, the immediate problem is these lines on the top third of the screen.

I appreciate your help.

 

[none]

Thanks for your feedback guys. However it's been so long since I've
poked around inside a monitor / TV that I am uncertain where to look.

Is the vertical section you refer to, the LOPT etc ?

I was considering looking on ebay for another one of these but if I
could resurrect this one, I would save a few pennies. However it is
possible, this unit may be on its way out. The brightness is up full, to
get a normal picture. When using separate chroma and luma inputs from
the C64 computer, colours still "interfere" with each other eg brown
text on a blue background is almost unreadable.

Anyhow, the immediate problem is these lines on the top third of the
screen.

I appreciate your help.

The 1084 was a good CGA monitor for the C=128, but for the C=64 any NTSC
analog video monitor will do (using composite video combining luminance
and chrominance information). Also, turning up the brightness / contrast
of your monitor may increase the visibility of retrace lines near the
top of the screen.
Do the lines disappear when you turn the brightness down?
If you have to turn it up to max brightness to view the monitor, your
CRT could be failing. The cost of replacing the CRT could be more than
that of a used PC.
On the other hand, most cheap analog color TV's will have RCA-type
sockets that will fit the composite video / audio cable provided with
the C=64. The yellow connector is the composite output of your Commodore
computer.

 

[James Sweet]

The 1084 was a good CGA monitor for the C=128, but for the C=64 any NTSC
analog video monitor will do (using composite video combining luminance
and chrominance information). Also, turning up the brightness / contrast
of your monitor may increase the visibility of retrace lines near the top
of the screen.
Do the lines disappear when you turn the brightness down?
If you have to turn it up to max brightness to view the monitor, your CRT
could be failing. The cost of replacing the CRT could be more than that of
a used PC.
On the other hand, most cheap analog color TV's will have RCA-type sockets
that will fit the composite video / audio cable provided with the C=64.
The yellow connector is the composite output of your Commodore computer.

If it were a CRT problem the retrace lines would fill the screen. When it's
just a few lines at the top, the problem is a capacitor at least 99% of the
time.

 

[ZACK]

target the caps that are around any hot spots
like near a hot resistor the vert chip itself
thay tend to dry out.