Acoustic 117 rectifier specs

[stereomonostereo]

Hey guys,

I'm attempting to fix up an old Acoustic 117 combo that had a small fire due to the previous owner installing a 20 amp fuse. I've replaced a bunch of bad components (output ICs, resistors, capacitors, etc.) and now i'm at the rectifier. The problem is that the schematic i have is cut off, and i'm not finding a cross reference for the odd part number. The rectifier reads '1480080 7923'. None of my acoustic cross reference sheets show a 480080. Anyone have any ideas? Thanks!

[52 Bill]

Is this a bridge or 4 separate diodes?

The dc fuse rating of 2 amps and the filter cap rating of 75 volts should give you and indication of the voltage and current draw of the amp.

Absolute minimums would be 3 amps and 100 volts, so add a safety factor to those figures and find something suitable. 6 amps and 200 volts?

[JacklegBassplayer]

The rectifier reads '1480080 7923'. None of my acoustic cross reference sheets show a 480080. Anyone have any ideas?

Several months ago I picked up an Acoustic 118 for cheap, which uses the same 170093 power amp PCB as the 117. The on-board bridge rectifier is a miniature GBPC6 package size.

This 118 had a little bit of hum, so I did a cap job. That didn't really help, so I swapped-in a new bridge rectifier in the off-chance that the old one had been previously stressed and was causing some of the hum. In their bigger amps Acoustic usually used 400V rectifiers, so I just found a 6A 400V version in that package --- a Vishay GBPC604-E4/51 from Mouser, $2.

The new rectifier worked fine, but it didn't help the hum problem and so I put the original 480080 back in. What I ended up doing to tame the hum was outboarding the rectifier, mounting it to the bottom of the chassis just like most all other Acoustic bridge rectifiers are mounted. That made a noticeable improvement. By the way, this 170093 PCB did not have an on-board 2-Amp pigtail fuse shown in the schematic; there was a jumper wire instead.

[stereomonostereo]

Okay, i think it's starting to make sense. For example, I'm currently working on an Ampeg V-6B, which has a fuse rating of 8 amps, and is receiving 56.5v out of the rectifier. So a suitable replacement would be something along the lines of a BR84, 8A and 400v? So like capacitors, voltage doesn't matter, so long as it's not under what it's rated at?

[gbono]

Okay, i think it's starting to make sense. For example, I'm currently working on an Ampeg V-6B, which has a fuse rating of 8 amps, and is receiving 56.5v out of the rectifier. So a suitable replacement would be something along the lines of a BR84, 8A and 400v? So like capacitors, voltage doesn't matter, so long as it's not under what it's rated at?

Half wave rectification: the peak reverse voltage of the circuit requires that the diode breakdown voltage must be greater than twice the DC voltage of the circuit

Full wave center tapped rectifcation: the PRV of the circuit also requires either diode to handle twice the DC output voltage.

Full wave bridge recification: PVR such that any non-conductiong diode in the bridge is equal to the peak voltage across the load

(taken from "Electronic Troubleshooting" - J Oleksy)

[JacklegBassplayer]

Yes, 400V is the peak reverse voltage rating. All the Acoustic bridge rectifiers I've bothered to look at have all been rated at 400V PRV. I got the 6A current rating version because that's the heaviest duty one I found in a GBPC6 package size. However, since I ended up moving the bridge rectifier from the PCB to the chassis, it wasn't really necessary to use the GBPC6 package after all.