JBL L212 restoration

[74sdta]

Working on bringing these back to their former glory. Like the PL gear, I acquired these from my uncle who purchased them new in the early 80's.

The L212 was a JBL 2.1 design from the late 70's. More info about the design;

https://www.lansingheritage.org/images/jbl/catalogs/1979-home/page2.jpg
https://www.lansingheritage.org/html/jbl/specs/home-speakers/1977-l212.htm

My pics to follow shortly.

 

[laatsch55]

Were they the the same as the L200?

 

[laatsch55]

nEVER MIND, NO THEY WEREN'T...

 

[74sdta]

The sub (Ultrabass in JBL terminology) has an amp (bass energizer) built into the bottom of the cabinet. These amps are known to have problems and I did not know what to expect when opening this one up. Well, someone has been in here before....


Two missing caps!

Like other boards of this era, if you wave the soldering iron over it, all the traces start jumping off the substrate. I was able to extract the remaining two caps and the patch job with only a couple of damaged pads.

 

[laatsch55]

Yeah, not made to repair...

 

[VSAT88]

Those are some very nice looking JBL's. I hope you all the luck in your restoration.

 

[74sdta]

Yeah, not made to repair...

They were not. The service manual has a note to use long nose pliers as a heatsink.

Those are some very nice looking JBL's. I hope you all the luck in your restoration.

Thanks!

 

[74sdta]

Tested the xmfr and it is good. The power and phase switch function but the power indicator lamp is bad. Went through the parts list in the service manual and the plan is to replace all resistors, rectifier, the small e-caps, and a couple of diodes.

As for the PS caps - there were 4x 2500MFD with a 5 leg/lead footprint. I think that I will go with 2x 10,000MFD snap-in type. Drill holes for leads and then point-to-point wire them with 18awg buss wire.