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Phill's 2252

Vintage happens... These are full of old parts and they can't all be changed in a rebuild. The back right corner is where the amp module is. As there is a bias current always flowing there will be heat coming out of that area. Perhaps what you noticed from pre restoration? Maybe the bias was too high.
 
rBuckner said:
Vintage happens... These are full of old parts and they can't all be changed in a rebuild. The back right corner is where the amp module is. As there is a bias current always flowing there will be heat coming out of that area. Perhaps what you noticed from pre restoration? Maybe the bias was too high.
Click to expand...

I had set the bias per the service manual, my money is either the driver pair I replaced blew again, or the other channels drivers popped. One channel had popped on the bench, seemingly doing nothing, wonder if both had been damaged from heat. Anyway, I've worked it out with him to take another look at it, hoping for the best.
 
So it's been a while on this one, got the unit back from Phil 2 months ago, just been so busy lately that I haven't really had time to throw it on the bench till last week (or so).

Wound up being the power switch... makes some nice arcing noises... Always knew something silly would come back to bite me in the butt.

Anyway, crisis averted.
 
Jonstigator said:
I always replace the power switch and install a new snubber. Such an easy task. Glad it was a easy fix and back with its daddy.
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Not back quite yet, but yes, was very glad it wasn't a thermonuclear level failure. I don't always swap them unless I'm having issues with them, as the old leaflet switches feel nicer than the new push styles. But yeah.
 
goldswimmerb said:
All that's left now is the tuner, got the preamp/tone board and phono board done. I used Nichicon UES and UPW for the electrolytic caps on this board due to lead diameter.

Tone board:
View attachment 1728820
Upgraded the input films to WIMA, the local DC filter cap was upgraded to 470uf if I recall (it's been a few days). The 10UF caps were upgraded to Nichicon UES as I ran out of 10uf UFG Capacitors. All small value Capacitors were upgraded to WIMA films, and I replaced the Transistors here with matched KSC1845/KSA992s, which while not necessary should offer some improvement given the lower noise of the modern parts.

Phono preamp:
View attachment 1728823
Here I upped the local DC filter Capacitor to 220uf. Small value lytic caps were replaced with WIMA films.
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Which cap was upgraded to 470uF? I had a working unit, upgraded the caps and transistors on the power supply board. Then I used it for 6 months and decided to upgrad the caps on the power amp. I am moving towards the tone board now. This is the area where all the magic happens. I am planning to make a few changes at a time and have a listen to see if they make any changes to the sound. Perhaps I could ask the experts here if there is a tangible measurement that I could make to quanfity improvements as I switch out the old with new caps and transistors.
 
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