2270 early model - stock or mod?

I have a 2270 serial number 1307. It has diodes across the filter caps, which tie into the amp outputs at the protection relay. Is this factory original or is this a modification? The receiver had been worked on before I got it. I've attached pictures.

The champagne face is sure pretty.

Never seen anything like that in a 2270. Looks like a mod.


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Does it still have the original bridge rectifier?

hirscwi said:

Does it still have the original bridge rectifier?

Click to expand...

The original bridge rectifier is still in place.

bktheking said:

Never seen anything like that in a 2270. Looks like a mod.

Click to expand...

I think it was a 'fix'. I removed it and now it blows a fuse at power up unless its on a DBT. Time to start tracking down the original problem.

Check your outputs.

That is the diode clamping mod, prevent reverse biasing of the outputs.

Not likely your issue.

Jk

Also have an early serial # 2270 (1000-3900) these amp module circuits aren't very stable at all. Mind the wiring changes on the J750s, and make sure you have the proper schematic for the amp, most were serviced quickly and have later replacement modules.

Tag a photo of an amp board, if you can.


---- Fuse likely wiring, check rail voltages and grounds since removing the diodes. Also worked on areas around relay and PS board for cooked bits.

- jstang, amazing, can you explain this diode clamping mod, I'm hoping it does what I think.

Goodluck!