I have a Punch 60x2 on the bench, powers up and idles fine, speaker outputs have 27.76v dc on both channels.
No visible damage, positive and negative rails test fine.
Any thoughts on this one?
No visible damage, positive and negative rails test fine.
Any thoughts on this one?
Same as the 60.2.
Contact Rockford tech support to get the schematic diagram.
The op-amps are the two 8-pin ICs behind the RCA jacks.
Contact Rockford tech support to get the schematic diagram.
The op-amps are the two 8-pin ICs behind the RCA jacks.
The negative regulator (LM337) appears to be defective. Post the DC votlage on all 3 terminals if you don't know how to check it.
Q9 is LM337
So I had to remove the heatsink clamp bars to see if Q8 or Q9 were LM337, after re assembly of the clamps I went to power up the amp and it immediately started drawing excessive current.
I figured one of the transistors must have breached the insulating strip as most the transistors were showing 0 ohms from centre pin to heatsink.
Sure enough it was Q9 so I added extra insulating pads to all the transistors and clamped them down.
Tested for 0 ohms from the centre legs to heatsink and all tested fine.
Powered up the amp and the DC accross the speaker terminals now reads 0.005v dc and 0.010v dc
Tested for audio and the amp is working fine again.
So I had to remove the heatsink clamp bars to see if Q8 or Q9 were LM337, after re assembly of the clamps I went to power up the amp and it immediately started drawing excessive current.
I figured one of the transistors must have breached the insulating strip as most the transistors were showing 0 ohms from centre pin to heatsink.
Sure enough it was Q9 so I added extra insulating pads to all the transistors and clamped them down.
Tested for 0 ohms from the centre legs to heatsink and all tested fine.
Powered up the amp and the DC accross the speaker terminals now reads 0.005v dc and 0.010v dc
Tested for audio and the amp is working fine again.
Thank you Perry for pointing me in the right direction.
Great advice as always.
I'll certainly check the insulating strip in future on these old RF amps.
Great advice as always.
I'll certainly check the insulating strip in future on these old RF amps.
I don't know what you did but if you stacked insulators, that reduces their efficiency. For the regulator, it's not significant but it could be for the FETs.
Yes I had stacked them, I've now removed the old strips and kept the new.
I'm sure it could have been one of the output transistors it was definitely one on the Q9 side.
I'm sure it could have been one of the output transistors it was definitely one on the Q9 side.
It had to be the regulator. The drains of the outputs (if 540/9540) are the ones that had the 27.6v on them. If they were shorting to the heatsink, it would have been drawing a lot of current.