Fisher 400 Issue/Repair

[grochon]

I bought a refurbished Fisher 400 a few years ago which has recently developed an issue: sometimes FM works fine but after the unit warms up the tuning eye opens up and no stations come in. After it cools down somewhat, I can receive stations on the far right of the scale (around FM105 and higher). It takes a longer cool down for the rest of the stations to come in. Is this something I could repair myself (I have a DMM and can solder but that's it)? If not, who is the best tube tuner expert around who could do the repair?

 

[gadget73]

Guessing at it, I'll say broken solder joint somewhere along the way. You might be able to narrow down the area by wiggling tubes or tapping around on the chassis to see if it comes back if you move a certain area.

Maybe throw a post up in the Fisher sub-forum, maybe someone will have specific ideas where to look.

 

[grochon]

I could re-solder the joints in the mpx section tomorrow to see what happens. I'll also post in the Fisher forum...thanks for the suggestion!

 

[Dadbar]

The next time it happens, try wiggling the tuner tubes (like the 6AU6's etc). It could be a loose tube socket that gets worse when things heat up.