Here is an amplifier made by a guy named "Hollon" some time in the 80s or maybe 90s? Can't remember his first name. Credit where credit is due, he made the outside look really sharp. A hard automotive-grade finish with properly-applied lettering and pin stripes.
But he made up for it by screwing up the inside of the amplifier.
If someone offers you an amplifier with that name and the automotive-grade gold finish on the face, run don't walk the other way. It's not so much an amplifier as a build-it-yourself partial kit. This one is meant to be a clone of the Pride DX300 amplifier.
He made a variety of types, from four to six to eight 3-500Z amplifiers. Saw one with a 4CX1000A that was just plain suicidal. He totally disregarded the drive-power limits for that tube. This one is intended to be a clone of the Pride DX300, but falls short here and there.
In this case, I can't blame Hollon for the 30-Amp fuse that caused the big high-voltage transformer to roach itself. Our replacement is a toroid type that just barely fits, but does the job. The factory-original transformer was sold by RF Parts until they ran out forever a few years back.
The small transformer provides power to the tube's heater, screen and control grids, relays and LEDs.
Just one problem. It's the wrong one. These resistors are just a hint.
So this amplifier will get both transformers replaced. DIY for sure. RF Parts ran out of the small one permanently around ten years ago.
Fortunately we also have a substitute for the small transformer that performs like it should. Definite DIY territory now.
This circuit board with the relays is the same one found in the Pride, and you can still buy the bare board with no components from RF Parts. But this guy didn't use sockets for the relays, just soldered them in. AFTER first reaming out the holes. Can't see putting a relay socket in it, with so little copper foil remaining to solder to it. No way the original relay will be reliable after this many years.
Good thing I have an outright replacement for that pc board on hand.
Of course the support pillars are placed differently from the Pride. Had to punch a hole at the front of the board.
Good thing I had a Whitney punch on hand. Drilling a hole that close to the edge would be annoying.
So, out of three printed circuit boards under the deck, all three get replaced. And both transformers. But only if I want it to work.
But wait, there's more.! The depth of the chassis front-to-back is a little shorter than the Pride. A standard circuit board is too wide, and won't slide into the guide slots.
The fix is blessedly simple.
The power-supply printed circuit boards under the deck are supposed to be held in place by the bottom cover. Just one problem. The underside of the chassis is almost an inch deeper than the Pride was. Gotta restrain the circuit boards from flopping about.
The guide slots were held in place by some long-dead glue that just let go.
But wait, there's more! How about the power switch? Makes me wonder how it lasted this long.
Holl500_pwr_sw
One other "feature" I don't care for is his habit of using a barrier strip to organize the 120-Volt primary circuit.
I just prefer to have all that stuff soldered securely.
And yes, it has a circuit breaker where the fuse holder used to be. No more "No-Blow Fuse" follies for this amplifier.
The original DX300 had a 1/16" thick rear panel. This thing has a sandwich of the chassis box and a separate rear panel.
Just one problem. The small circuit breaker's threaded bushing is not deep enough for a panel that thick, plus a lockwasher.
Had to remove the rear panel and punch a clearance hole so the breaker's nut can be tightened. Shoulda been more careful getting the hole in the chassis line up with the clearance hole in the back panel. You can't simply drill into two layers of sheet metal at once. Just doesn't work like you think it should.
While the rear panel was loose, this was the perfect time to install a couple of the original-style circuit board guide rails. It snaps into two holes in the chassis deck, but for only one layer of metal. Requires a clearance hole in the rear panel like the small circuit breaker. At least these don't come loose and slide around when the glue lets go.
Seems to me this forum limits you to 20 images per post, and I'm about to exceed that. Wrap up will spill into another post.
Film at 11.
73
But he made up for it by screwing up the inside of the amplifier.
If someone offers you an amplifier with that name and the automotive-grade gold finish on the face, run don't walk the other way. It's not so much an amplifier as a build-it-yourself partial kit. This one is meant to be a clone of the Pride DX300 amplifier.
He made a variety of types, from four to six to eight 3-500Z amplifiers. Saw one with a 4CX1000A that was just plain suicidal. He totally disregarded the drive-power limits for that tube. This one is intended to be a clone of the Pride DX300, but falls short here and there.
In this case, I can't blame Hollon for the 30-Amp fuse that caused the big high-voltage transformer to roach itself. Our replacement is a toroid type that just barely fits, but does the job. The factory-original transformer was sold by RF Parts until they ran out forever a few years back.
The small transformer provides power to the tube's heater, screen and control grids, relays and LEDs.
Just one problem. It's the wrong one. These resistors are just a hint.
So this amplifier will get both transformers replaced. DIY for sure. RF Parts ran out of the small one permanently around ten years ago.
Fortunately we also have a substitute for the small transformer that performs like it should. Definite DIY territory now.
This circuit board with the relays is the same one found in the Pride, and you can still buy the bare board with no components from RF Parts. But this guy didn't use sockets for the relays, just soldered them in. AFTER first reaming out the holes. Can't see putting a relay socket in it, with so little copper foil remaining to solder to it. No way the original relay will be reliable after this many years.
Good thing I have an outright replacement for that pc board on hand.
Of course the support pillars are placed differently from the Pride. Had to punch a hole at the front of the board.
Good thing I had a Whitney punch on hand. Drilling a hole that close to the edge would be annoying.
So, out of three printed circuit boards under the deck, all three get replaced. And both transformers. But only if I want it to work.
But wait, there's more.! The depth of the chassis front-to-back is a little shorter than the Pride. A standard circuit board is too wide, and won't slide into the guide slots.
The fix is blessedly simple.
The power-supply printed circuit boards under the deck are supposed to be held in place by the bottom cover. Just one problem. The underside of the chassis is almost an inch deeper than the Pride was. Gotta restrain the circuit boards from flopping about.
The guide slots were held in place by some long-dead glue that just let go.
But wait, there's more! How about the power switch? Makes me wonder how it lasted this long.
Holl500_pwr_sw
One other "feature" I don't care for is his habit of using a barrier strip to organize the 120-Volt primary circuit.
I just prefer to have all that stuff soldered securely.
And yes, it has a circuit breaker where the fuse holder used to be. No more "No-Blow Fuse" follies for this amplifier.
The original DX300 had a 1/16" thick rear panel. This thing has a sandwich of the chassis box and a separate rear panel.
Just one problem. The small circuit breaker's threaded bushing is not deep enough for a panel that thick, plus a lockwasher.
Had to remove the rear panel and punch a clearance hole so the breaker's nut can be tightened. Shoulda been more careful getting the hole in the chassis line up with the clearance hole in the back panel. You can't simply drill into two layers of sheet metal at once. Just doesn't work like you think it should.
While the rear panel was loose, this was the perfect time to install a couple of the original-style circuit board guide rails. It snaps into two holes in the chassis deck, but for only one layer of metal. Requires a clearance hole in the rear panel like the small circuit breaker. At least these don't come loose and slide around when the glue lets go.
Seems to me this forum limits you to 20 images per post, and I'm about to exceed that. Wrap up will spill into another post.
Film at 11.
73
