Wanted to let you know I got it fixed! There are two 2uf 'lytics in the mpx unit that had failed, I replaced them and it works fine. Not much seperation but at least it sounds "stereo...ish.."
Great bass out of what would be considered a table radio, although it is a table radio on steroids for sure. I'm mad at myself for using fornbys on the front panel though, as I found out the wood on that peice was PAINTED on...
gonna have to make me a peice of oak to replace it now. Oh well.
Fm reception is pretty poor... my GE musaphonic table radio nails the FM stations every time WITHOUT an antennae, so I don't quite know whats going on here. All the tubes test fine
Anyways about the other amp, is there anyone out there that has one that runs hot? Mine is absolutly roasting! I took a turkey thermometer and stuck it on the power tranny and it got up to 190* F!
It seems to do this just sitting there without a load too, as I recently took it out of the amp and powered it up. I did take the end bells off and remove a LOT of potting to increase cooling, which dropped it down to around 170*F. I even tried a voltage reducer (6.3v bucking transformer) but it still seems to get hot. The one in the radio does not get anywhere near as hot during normal operation. Something I have always wondered, do transformers that were designed for a much greater load run hotter when they have to do light duty work?
Great bass out of what would be considered a table radio, although it is a table radio on steroids for sure. I'm mad at myself for using fornbys on the front panel though, as I found out the wood on that peice was PAINTED on...
gonna have to make me a peice of oak to replace it now. Oh well.Fm reception is pretty poor... my GE musaphonic table radio nails the FM stations every time WITHOUT an antennae, so I don't quite know whats going on here. All the tubes test fine
Anyways about the other amp, is there anyone out there that has one that runs hot? Mine is absolutly roasting! I took a turkey thermometer and stuck it on the power tranny and it got up to 190* F!
It seems to do this just sitting there without a load too, as I recently took it out of the amp and powered it up. I did take the end bells off and remove a LOT of potting to increase cooling, which dropped it down to around 170*F. I even tried a voltage reducer (6.3v bucking transformer) but it still seems to get hot. The one in the radio does not get anywhere near as hot during normal operation. Something I have always wondered, do transformers that were designed for a much greater load run hotter when they have to do light duty work?
It sounds to me like the power transformer has a partially shorted winding and the safest solution is to replace it with a suitable Hammond or Allied. I had to do this on the one I used to have when overseas. (Somebody plugged it into 220V and it was rated for 120V operation only..) I got it for a song as a consequence, about the equivalent of $15.00..
I'll have to agree - this is a GREAT little amp!
I just want to say thanks for the schematics!! I've looked all over the place for these with no luck...
I actually salvaged one of these little amps (and the speakers) from a curbside trashpile about three years ago (my Leatherman tool paid for itself, LOL!). Anyway, it seems that the local Salvation Army just didn't think it was worth selling as it was *just* a record player.
I've been using mine with a pair of JBL bookshelf speakers and it sounds pretty nice, except that the RIAA equalization network exaggerates the bass response. I've been getting around this by using my laptop as a signal source and attenuating the bass using the built-in EQ in Winamp. Now I can get rid of the network and hook up other sources - Woo Hoo!!!!
Thanks again, guys...
I just want to say thanks for the schematics!! I've looked all over the place for these with no luck...
I actually salvaged one of these little amps (and the speakers) from a curbside trashpile about three years ago (my Leatherman tool paid for itself, LOL!). Anyway, it seems that the local Salvation Army just didn't think it was worth selling as it was *just* a record player.
I've been using mine with a pair of JBL bookshelf speakers and it sounds pretty nice, except that the RIAA equalization network exaggerates the bass response. I've been getting around this by using my laptop as a signal source and attenuating the bass using the built-in EQ in Winamp. Now I can get rid of the network and hook up other sources - Woo Hoo!!!!
Thanks again, guys...
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