| Author | Message | ||
| Sean Borton (codamedia) Username: codamedia Registered: 03-2014 |
This is on a 212 Sixty Five Chassis #2475-65 SS Phase Inverter. (from 1979) I suspect I have a failing IC at the start of the normal channel (IC1). When I turn up the volume (on the normal channel) with nothing plugged in, I can hear some interference, yet when I turn up the Reverb / Vibrato channel - it is very quiet. After reading a few other posts, it was suggested to move IC5 (reverb driver) to the IC1 position. How do you remove these IC's on the 2475-65? They are the circular LM307H but appear to be on a riser or socket... Do they pull out like the later models with standard looking chips - or do I have to unsolder them from the bottom? | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
They are in sockets. Pull gently. If they break, you will have a hell of a time finding replacements. Most people are using brown dog adapters and using contemporary 8 pin IC's with the socket adapters. Make SURE you orient yourself with HOW they go in the sockets(direction) Mike | ||
| Sean (codamedia) Username: codamedia Registered: 03-2014 |
Thanks for the info Mike.. I thought they were in a socket but didn't want to tug too hard until I new for sure... Out of curiosity, are those TO-99 sockets? | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
Yes. |
Tue, 03/25/2014 - 09:55
#1
I finally opened up my amp
I finally opened up my amp again and tried the swap between IC1 (channel 1 pre-amp) and IC5 (reverb send).
Results = Really bad, and Really good... Not what I was expecting...
Channel one got really thin sounding to the point of unusable. On the other hand - the Reverb I always hated because is sounded so thin got really warm and inspiring. So this tells me IC5 was REALLY BAD while IC1 had a little added noise.
Does that mean I should look at replacing the IC's one by one? Or are the connections like tube sockets, where a little cleaning can go a long way? Sure, I can just try and see what happens (I'm sure it can't hurt, and I certainly intend to try) but I'm just checking to see what others have experienced.
IC's
Just my opinion but I would jus try cleaning first because it costs NOTHING and I'm cheap! After that, I think I would PROBABLY invest in a few brown dog adapters and swap out the IC's with currently available units. The brown dog adapters will allow the use of updated ic's. If you want, here's a link to the OLD board with a GREAT discussion with Ed Goforth doing the hard work to get some answers.
http://www.pacair.com/discus/messages/22/593.html?1303540949
That would be MY tact at this point. Just my crappy opinion though. Mike.
I'm thinking exactly the same
I'm thinking exactly the same thing... Never any harm in trying a good cleaning...
I'm going to order some brown dogs and sockets, that will open a few options down the road. ALSO - thanks for posting that link in this thread... I have read it before - but it' nice to have it accessible and in context...