Hi all,
I'm repairing this old PAL test pattern generator. The worst problem is
mechanic so far: all the presets push-buttons for VHF and UHF are blocked.
I have removed the whole RF generator assembly out of the instrument
but now, I'm not understanding how to access the internal mechanism of every
preset so I can clean it. It seems that the whole assembly has to be taken
apart to reach the rotating parts. There's only a very bad quality service
manual on the net and it doesn't have mechanical diagrams it seems.
Does anyone know better?
Thanks in advance
Frank IZ8DWF

On 25/07/2016 20:07, frank wrote:
Hi all,
I'm repairing this old PAL test pattern generator. The worst problem is
mechanic so far: all the presets push-buttons for VHF and UHF are blocked.
I have removed the whole RF generator assembly out of the instrument
but now, I'm not understanding how to access the internal mechanism of every
preset so I can clean it. It seems that the whole assembly has to be taken
apart to reach the rotating parts. There's only a very bad quality service
manual on the net and it doesn't have mechanical diagrams it seems.
Does anyone know better?
Thanks in advance
Frank IZ8DWF


I pulled the complete pm5507 manual off the shelf, probably 1966.
No exploded views or dismantling details

N_Cook wrote:
On 25/07/2016 20:07, frank wrote:

I pulled the complete pm5507 manual off the shelf, probably 1966.
No exploded views or dismantling details

thanks for trying!
I'm going to spray the mechanics from outside and hope it will unlock the
presets. I've found on the manual how to align the tuning mechanism after
removing one (or both) the RF assemblies, but I'd rather avoid doing that.
All the electronics appear mostly OK, probably a lot of the old electrolitics
will need to be replaced.
Frank

frank wrote:
Hi all,
I'm repairing this old PAL test pattern generator. The worst problem is
mechanic so far: all the presets push-buttons for VHF and UHF are blocked.
I have removed the whole RF generator assembly out of the instrument
but now, I'm not understanding how to access the internal mechanism of every
preset so I can clean it. It seems that the whole assembly has to be taken
apart to reach the rotating parts. There's only a very bad quality service
manual on the net and it doesn't have mechanical diagrams it seems.

I could unlock all the presets. There's enough room from the top of the
mechanism to spray on all the screws and unlock the tuners.
A bottom plate can be removed to better access the 4 rightmost tuners.
After that, the knobs have to be freed from the shaft as it turns out
that they need to slide in and out to allow both tuning and latching
of the presets. If they don't slide, it's impossible to latch the preset
in the IN position.
Now there's one final problem, the knobs look too short! If I install
the knobs again, the presets don't latch anymore, the internal shaft
has not enough room to extend far enough to allow the mechanism to reach
the latching position.
This is really puzzling, how can this happen? The knobs are the only platic
parts, so I guess they might have shrank just a little. I may have to try
working the internal end with a drill bit to make the necessary clearance.
This repair is requiring lots of time so far.

Frank

"frank" wrote in message
...
N_Cook wrote:
On 25/07/2016 20:07, frank wrote:

I pulled the complete pm5507 manual off the shelf, probably 1966.
No exploded views or dismantling details

thanks for trying!
I'm going to spray the mechanics from outside and hope it will unlock the
presets. I've found on the manual how to align the tuning mechanism after
removing one (or both) the RF assemblies, but I'd rather avoid doing that.
All the electronics appear mostly OK, probably a lot of the old
electrolitics
will need to be replaced.
Frank

My experience with a colour bar generator was a cheap kit built job - the
modulator was very cheap & nasty and fixed frequency.

My solution was to graft in the modulator from a scrap VCR. Most have a
preset screw to move the channel - but its not designed for frequent
adjustment.