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


It is currently Jul Mon 22, 2019 8:29 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 8 posts ] 
Author Message
 Post subject: Seeburg M-100 5U4G question
PostPosted: Apr Sat 20, 2019 5:07 am 
Member
User avatar

Joined: Apr Sat 02, 2016 4:29 am
Posts: 139
Location: Garland, Texas
Hello,
Completed rebuilding the amp on the M-100 (MRA1-L6) and I also rebuilt the Selection Receiver (W5R5-L6). Unfortunately I don't have the entire manual, just the schematics. I really wanted to check the audio before I drove back out to the jukebox (90 miles) but noticed I was not getting power to the 5U4G. All other tubes are getting filament voltage. I checked the 5U4G that was with the amp and it was dead so I replaced with a good (tested) 5U4G. I still couldn't get audio. (phone audio 3.5mm to RCA into the amp). Started checking with VOM and no DC voltage. Question is does the credit unit have to be connected to the jukebox selection to send power to the 5U4G? I seem to remember that in the late 50's or 60's they started doing something similar so that it would save the 5U4G and all the heat they put out. If not, what would cause no power to the 5U4G or B+ DC? I replaced the selenium rectifier with a modem diode and it is working properly.
Any ideas are welcome! Thank you!
Rudy


Top
 Profile  
 
 Post subject: Re: Seeburg M-100 5U4G question
PostPosted: Apr Sat 20, 2019 5:15 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 10417
Location: Redlands CA
The 5U4 only lights when the machine is in play mode, this keeps the B+ turned off when in standby.
Not quite sure how they accomplish that but I suspect there's probably a way to bypass it.


Top
 Profile  
 
 Post subject: Re: Seeburg M-100 5U4G question
PostPosted: Apr Sat 20, 2019 5:26 am 
Member
User avatar

Joined: Apr Sat 02, 2016 4:29 am
Posts: 139
Location: Garland, Texas
Thanks again Eric. If you or anyone else can think up a bypass to save me a 180 mile round trip test session I would really appreciate it!

Rudy


Top
 Profile  
 
 Post subject: Re: Seeburg M-100 5U4G question
PostPosted: Apr Tue 23, 2019 1:19 am 
Member

Joined: Aug Sat 01, 2009 2:23 pm
Posts: 1655
Eric H wrote:
The 5U4 only lights when the machine is in play mode, this keeps the B+ turned off when in standby.
Not quite sure how they accomplish that but I suspect there's probably a way to bypass it.


The winding for the 5U4 is in the transformer on the selection receiver.They need to be plugged together in order for the amp to work.

_________________
John Stone
Antique Radio Club of Illinois


Top
 Profile  
 
 Post subject: Re: Seeburg M-100 5U4G question
PostPosted: Apr Tue 23, 2019 4:36 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 10417
Location: Redlands CA
I'm guessing the Play relay on the receiver has to be engaged, not really do-able with out the mechanism unless you can just wedge it closed.


Top
 Profile  
 
 Post subject: Re: Seeburg M-100 5U4G question
PostPosted: Apr Tue 23, 2019 4:38 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 10417
Location: Redlands CA
Looking at a schematic (for a model C) it appears the transformer to the 5U4 is on the Amp side and the AC voltage comes from the receiver, guessing 115 AC so may be possible to just wire it up?


Top
 Profile  
 
 Post subject: Re: Seeburg M-100 5U4G question
PostPosted: Apr Wed 24, 2019 3:04 pm 
Member

Joined: Aug Sat 01, 2009 2:23 pm
Posts: 1655
Eric H wrote:
Looking at a schematic (for a model C) it appears the transformer to the 5U4 is on the Amp side and the AC voltage comes from the receiver, guessing 115 AC so may be possible to just wire it up?


Sorry, had it reversed. The 6.3 volts winding for all the amp tube heaters comes from the transformer in the selection receiver. The 5 volt winding is on the power transformer for the amp. Both amp and receiver have to be plugged together for this to work.

_________________
John Stone
Antique Radio Club of Illinois


Top
 Profile  
 
 Post subject: Re: Seeburg M-100 5U4G question
PostPosted: May Mon 27, 2019 4:15 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 8842
Location: Beaver Falls, PA. USA
The power to the amplifier comes on at the same time as the mechanism motor. As was mentioned, the tube heaters are fed from the transformer on the selection receiver.

If the motor runs but the amplifier does not come on, look for a blown fuse on the amp chassis. Also, some models have a jumper in the speaker plug, which connects the center tap of the HV secondary winding of the power transformer to ground. If the speaker is unplugged, the B+ will be off.

I don't have any access to my drawings right now to give any more info, but the fuse would be the first thing to check.

_________________
Tim KA3JRT


Top
 Profile  
 
Post New Topic Post Reply  [ 8 posts ]  Moderator: Alan Voorhees

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 6 guests



Search for:
Jump to:  
cron


























Privacy Policy :: Powered by phpBB