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Model 18 Scope Troubleshooting

Thanks for posting the image of your selector switch bktheking. The pop on my unit is a deep thump, not a click.

Here's my switch for comparison. One difference I notice. On mine, there are are 3 orange wires on the lower level - 1 incoming 200 volts and 2 wires outgoing 200 volts to different boards. On your switch, I don't see the incoming 200volt wire (only the 2 outgoing 200 volt wires). Is in your incoming 200 volt supply wire entering the switch in a different location? Or maybe that incoming wire is present on your unit on the lower level but the camera angle doesn't show it?

selectorswitch.jpg
 
In the process of doing the final testing on my Model 18 before I put it in storage or sell. I did the selector switch jumper to eliminate the pop and I am happy with that.
My stereo lamp indicator has always worked well but today it flickers on and off. Mostly off. Any thoughts? Should I replace it and if so do I have to cut open the existing lamp to replace the neon bulb?
 
Fhamre said:
In the process of doing the final testing on my Model 18 before I put it in storage or sell. I did the selector switch jumper to eliminate the pop and I am happy with that.
My stereo lamp indicator has always worked well but today it flickers on and off. Mostly off. Any thoughts? Should I replace it and if so do I have to cut open the existing lamp to replace the neon bulb?
Click to expand...

Assuming that it's actually still in stereo then you may just have a bad stereo lamp or stereo LDR lamp.

When you have the scope set to audio display do you see a change to mono that corresponds to the lamp?
 
If it's flickering it's not the lamp, it's either alignment or possibly the mod you applied to the switch- if it was working fine before.
 
It flickers in all modes not just FM. Sometimes it stays on for quite awhile then it starts to flicker.When the lamp is working if I push it to mono the light goes out.
 
It flickers in all modes because your 200V is jumpered out, the tuner will be on all the time including the stereo indicator if it's tuned in regardless of the mode.

If you look at the scope can you see it switch between stereo and mono as the lamp flickers while it's on FM?
 
Been playing for hours. No flicker,hmm.
I'm ordering some neon lamps to have on hand.
Does it require one to remove the dial glass in order to replace the stereo lamp?
 
I should have been a bit more clear on looking at the scope.

You can see on the scope the difference between stereo and mono. If the scope is showing that the tuner is in stereo and the lamp is flickering then the bulb or LDR may have a problem. If the scope and stereo lamp seem to be jumping in and out of stereo together the the bulb is probably ok and your problem may line in the tuner.
 
The flickering is now back. The scope still shows the tuner is in stereo with the flickering. Conversely when it is in mono the flickering has no affect on the scope.
 
The service manual describes a modification that jumpers out LDR 602.. If this has not been completed on your receiver it may be the problem.

It's all in a service builiten... If you don't have it shoot me a PM...
 
You need to remove the dial glass and the black tole.
Strange that this lamp is dead, it's very reliable.
This lamp work only on FM, have you tried to adjust R512 (Service Manual page 5).
 
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Fhamre,

Do you have LEDs for your two side dial lights or #1847 incandescent bulbs? I noticed that my stereo neon indicator light would flicker when I had LEDs in place for the dial lights. When I replace the dial LEDs with regular 1847 incandescent bulbs, the neon light no longer flickers.
 
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