This seems to be the time to be running thru Ampeg SVT's for me. A new SVT Heritage amp arrived from a client. I hadn't seen one of these before. On the rear grille, the Model label plate has the remark 'Designed and Assembled in the USA'. What that really means is all the PCB assemblies, wire harnesses, chassis', cabinets can be manufactured off shores, be it China, Viet Nam, Korea, etc. They integrate all the sub-assemblies into the final product here in the USA, so they can legally make that claim 'Assembled in the USA'.
It's an SVT-CL, from what I could see. Black PCB's, just to make it harder to follow circuit traces. Metric hardware everywhere, AND.....sourced out of China. That means SOFT steel. Philips pattern fails with the greatest of ease. While Ampeg is trying to address the loose hardware problems, they've done it in a fashion to make the amp UNSERVICABLE. They've put thread lock compound on the ends of screws that you DO need to remove to pull assemblies apart to repair it.
As usual, loose power and output transformers. So, the main power amp PCB has to come out to access two of the four screws. The three rear PCB screws.....thread-locked. They began backing out, then locked up, and the Philips pattern in the soft steel screws begin radiusing! The two screws holding the AC Mains PCB in place.....one sheered right off...thread lock compound again. I was able to remove the standoffs on the main PCB, as they didn't bother to put thread lock compound on the chassis end of the standoffs. I did get the main board out, and used a M3 tap to help cut out the partially hardened thread lock compound, along with Acetone to cut it. I tried the accetone on the one of the rear screws of the AC mains board (also M3.5), but lost that battle. . I'm not in the mood to drill out and re-tap the pressed-in round standoff for that board. I'll have to trust the solder joints on the IEC connector and the AC mains fuse on that PCB assy for a while, and deal with it later. Arrrrggggghhhhhh!
I haven't yet pulled the preamp apart, but when i removed the power tube PCB, what do I find for the Screen resistors? 1/2W 22 ohm carbon film resistors. They changed those out to 220 ohm flame-proof 1/2W parts years ago. I've always used small body 2W Metal Oxide 220's there. At least they didn't thread-lock the cover panel screws to access the power tube PCB assy!
So far, not impressed with this amp, at least from a service standpoint. I fear Ampeg has done this with all their new amps...not just this Heritage model.
It's an SVT-CL, from what I could see. Black PCB's, just to make it harder to follow circuit traces. Metric hardware everywhere, AND.....sourced out of China. That means SOFT steel. Philips pattern fails with the greatest of ease. While Ampeg is trying to address the loose hardware problems, they've done it in a fashion to make the amp UNSERVICABLE. They've put thread lock compound on the ends of screws that you DO need to remove to pull assemblies apart to repair it.
As usual, loose power and output transformers. So, the main power amp PCB has to come out to access two of the four screws. The three rear PCB screws.....thread-locked. They began backing out, then locked up, and the Philips pattern in the soft steel screws begin radiusing! The two screws holding the AC Mains PCB in place.....one sheered right off...thread lock compound again. I was able to remove the standoffs on the main PCB, as they didn't bother to put thread lock compound on the chassis end of the standoffs. I did get the main board out, and used a M3 tap to help cut out the partially hardened thread lock compound, along with Acetone to cut it. I tried the accetone on the one of the rear screws of the AC mains board (also M3.5), but lost that battle. . I'm not in the mood to drill out and re-tap the pressed-in round standoff for that board. I'll have to trust the solder joints on the IEC connector and the AC mains fuse on that PCB assy for a while, and deal with it later. Arrrrggggghhhhhh!
I haven't yet pulled the preamp apart, but when i removed the power tube PCB, what do I find for the Screen resistors? 1/2W 22 ohm carbon film resistors. They changed those out to 220 ohm flame-proof 1/2W parts years ago. I've always used small body 2W Metal Oxide 220's there. At least they didn't thread-lock the cover panel screws to access the power tube PCB assy!
So far, not impressed with this amp, at least from a service standpoint. I fear Ampeg has done this with all their new amps...not just this Heritage model.
Comment