Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Dec Thu 02, 2021 11:42 pm


All times are UTC [ DST ]





Post New Topic Post Reply  [ 3 posts ] 
Author Message
 Post subject: GE P-780A obversion
PostPosted: Oct Tue 05, 2021 10:39 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 12180
Out of the realm of normalness but my daily player increases volume as it plays. I can set it for approx a background volume and assuming I doze off, a couple hours later volume has increased till it wakes me up. Clarity is fine, just loud. Took awhile before I considered it had a problem. Finally switched to another 780, volume stays same. To troubleshoot I'll suppose I'll have to warm chassis and blip various components with circuit cooler till volume drops. Suspect the audio driver. One in this set started life as a output, it's PP sister was out of spec & driver was noisy so I switched it's duty.

Not mentioned, offender is one of two I converted to silicon output transistors. The substitute 780 is other converted set, does not have volume issue.

_________________
Tom


Top
 Profile  
 
 Post subject: Re: GE P-780A obversion
PostPosted: Oct Tue 05, 2021 4:12 pm 
Member

Joined: Oct Mon 26, 2009 10:02 pm
Posts: 7168
Location: Indianapolis, IN
Hey Tom,

Be sure to let us know outcome !


Top
 Profile  
 
 Post subject: Re: GE P-780A obversion
PostPosted: Oct Tue 05, 2021 5:33 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 12180
xrhonda91 wrote:
Hey Tom,

Be sure to let us know outcome !

OK John, may be awhile, I kinda like it as is. Consider this A(only one I have) as best sounding 780 in fleet. Has real punch to lows can bump 1W on meter. Actual spec is 500mw, 750 max(yeah I know it's stated one watt on net, not what GE specs say). It's always seemed "hard" on batteries. Measured current draw awhile back and is at high end of spec, can't get something for nothing. I've added a 9v connector and it easily runs a month plus on rechargeable AA batts. The other converted 780(B) certainly has better battery life, but doesn't have same low end oomph.

Will be changing gears soon.

Years ago I picked up a freebie Arvin 9632. Hiding so long almost thought I'd been dreaming, still 90% sure I had one. It's case is fairly nice, knobs present, no battery damage or obvious prior repairs,. Still it needs lots of love. I've breezed through the schematic, will study your restoration photos before tackling this one.

_________________
Tom


Top
 Profile  
 
Post New Topic Post Reply  [ 3 posts ]  Moderator: Dave Doughty

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 7 guests



Search for:
Jump to:  




































Privacy Policy :: Powered by phpBB