Pride DX300. Works until the owner gets it home.

[nomadradio]

Here's a hack prompted by frustration.

Sent this Pride DX300 home with the owner after replacing failed circuit boards. Owner reports it won't do anything when he got it home.

Found we had sold him a bad relay. New relay made it work like it should. Sent it home.

Called back, says it won't do anything. Dern!

Brought it back, couldn't duplicate his problem. It worked first time, every time for us.

Puzzling. Then again, first thing we do when this model gets evaluated is pull the tube and see what the tester says about it. This is cheap insurance, since a tube failure tends to damage components in this model. Tube tested just fine. The amplifier works like it should, can't make it fail.


Took it home the third time still no wattage. Brought it back. Gotta give this guy credit for still being friendly even after the third time it took a dump on him.

This suggests that the tube has been coming loose in the socket. The pins on the 4CX250 tube are small, and the tube is top heavy. There's just not enough friction in the tube socket to hold the tube properly square against the chassis deck. And if that was the problem, I obscured it by pulling out the tube to test it before plugging in the power cord. Naturally when I placed it back (squarely) in the socket, this would cure the issue, but not exactly on purpose.

This should take care of the jostle problem. Gonna have to locate a supply of 2-inch tall ceramic pillars, or maybe just make my own from teflon dowel. Leads me to wonder if it's an upgrade we should perform routinely. Ceramic pillars have been getting expensive lately.

This looked like the simplest solution. With any luck he can finally get the thing to work for him once he gets it home.

73

 

[jtrouter]

Here's a hack prompted by frustration.

Sent this Pride DX300 home with the owner after replacing failed circuit boards. Owner reports it won't do anything when he got it home.

Found we had sold him a bad relay. New relay made it work like it should. Sent it home.

Called back, says it won't do anything. Dern!

Brought it back, couldn't duplicate his problem. It worked first time, every time for us.

Puzzling. Then again, first thing we do when this model gets evaluated is pull the tube and see what the tester says about it. This is cheap insurance, since a tube failure tends to damage components in this model. Tube tested just fine. The amplifier works like it should, can't make it fail.


Took it home the third time still no wattage. Brought it back. Gotta give this guy credit for still being friendly even after the third time it took a dump on him.

This suggests that the tube has been coming loose in the socket. The pins on the 4CX250 tube are small, and the tube is top heavy. There's just not enough friction in the tube socket to hold the tube properly square against the chassis deck. And if that was the problem, I obscured it by pulling out the tube to test it before plugging in the power cord. Naturally when I placed it back (squarely) in the socket, this would cure the issue, but not exactly on purpose.

This should take care of the jostle problem. Gonna have to locate a supply of 2-inch tall ceramic pillars, or maybe just make my own from teflon dowel. Leads me to wonder if it's an upgrade we should perform routinely. Ceramic pillars have been getting expensive lately.

This looked like the simplest solution. With any luck he can finally get the thing to work for him once he gets it home.

73

Now you have to update us if it fixed his problem.

 

[nomadradio]

He requested that we keep it for a week, and hook it up a few times to see if it changes its mind while it's here. So far so good, works first time every time.

Once he's ready to come get it we'll see if this cures the problem when he gets it home.

73

 

[linearone]

Here's a hack prompted by frustration.

Sent this Pride DX300 home with the owner after replacing failed circuit boards. Owner reports it won't do anything when he got it home.

Found we had sold him a bad relay. New relay made it work like it should. Sent it home.

Called back, says it won't do anything. Dern!

Brought it back, couldn't duplicate his problem. It worked first time, every time for us.

Puzzling. Then again, first thing we do when this model gets evaluated is pull the tube and see what the tester says about it. This is cheap insurance, since a tube failure tends to damage components in this model. Tube tested just fine. The amplifier works like it should, can't make it fail.


Took it home the third time still no wattage. Brought it back. Gotta give this guy credit for still being friendly even after the third time it took a dump on him.

This suggests that the tube has been coming loose in the socket. The pins on the 4CX250 tube are small, and the tube is top heavy. There's just not enough friction in the tube socket to hold the tube properly square against the chassis deck. And if that was the problem, I obscured it by pulling out the tube to test it before plugging in the power cord. Naturally when I placed it back (squarely) in the socket, this would cure the issue, but not exactly on purpose.

This should take care of the jostle problem. Gonna have to locate a supply of 2-inch tall ceramic pillars, or maybe just make my own from teflon dowel. Leads me to wonder if it's an upgrade we should perform routinely. Ceramic pillars have been getting expensive lately.

This looked like the simplest solution. With any luck he can finally get the thing to work for him once he gets it home.

73

I'm building another deck , a three tube Z box. I finished everything up yesterday and decided to set up the tank circuit. Usually this is a trivial matter. My math is always right and Ive done it countless times.
This time the world was against me. I futzed with it for wayyyy too much time. It looked like I wasn't even close. I finally disassembled the entire top end, changed coaxial cable inside the deck, I had temporary tank coils and trimmers, was redoing grounds... Every thing you can think of. I walked away and hit it again today. I started by wiping all contact points with scotchbrite and acetone. Somewhere in reassembly the problem resolved itself. I must have had either bad coax or a slightly bad connection point. It resolved itself and then tuned up perfectly.
The slightest connection issues can be the worst horrible, hard to diagnose issues.

 

[nomadradio]

Now you have to update us if it fixed his problem.

Kept it all week, worked each day when tested. Sent it home with the owner Fri 6/23.

Fingers crossed.

73

 

[walterjn]

Kept it all week, worked each day when tested. Sent it home with the owner Fri 6/23.

Fingers crossed.

73

How far away is the owner's base from you?

 

[nomadradio]

How far away is the owner's base from you?

Other side of Jefferson County, more or less.

73

 

[walterjn]

Other side of Jefferson County, more or less.

73

Close enough for you to drive over and take a look at his place if it doesn't work again?? Wondering if transportation and whatnot might be bouncing things around...

 

[nomadradio]

In this business no news is frequently good news. Haven't heard back from him. Makes me wonder if we'll need to do this more often. Replacing the original socket isn't as easy as it looks, even after drilling out the four rivets. Turns out that version is kinda rare. Even then, the added friction on the pins wouldn't compensate for the top-heavy weight of the tube. As the old saying goes: "Torque is cheap".

73