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I got some of those yellow paper covered electrolytic at the "drake going out of business sale". I should see if they're leaky or not.

John

On Mon, Jan 27, 2025 at 5:06?PM Steve Wedge, W1ES/4 via <w1es=[email protected]> wrote:

Yep and the interesting thing is that the earlier TR-4 can cap doesn't fail like the newer one.

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

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On Monday, January 27th, 2025 at 3:53 PM, DavidC KD4E via <qrv=[email protected]> wrote:

Talk about tunnel-vision!

He said TR-4 and it never even occurred to me to even look closely

at the faceplate.

We were standing in a non climate-controlled space while talking,

and it was cold.

'And that's my story, and I'm sticking to it ..."

Now, I have to learn what the difference is between the TR-4 and

the TR-4C.

Thanks!

On 1/27/25 14:43, Steve Wedge, W1ES/4 via wrote:

Exactly, which means that any kid or critter could touch dangerous voltages.

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

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On Monday, January 27th, 2025 at 12:32 PM, VE7PS via <ve7ps@...> wrote:

And the AC-3 did not have a top cover like the AC-4.

PS

On Mon, Jan 27, 2025 at 9:28?AM Steve Wedge, W1ES/4 via <w1es=[email protected]> wrote:

The circuit board for the rebuild kit mounts on top of the chassis. You can also do a 1 for 1 replacement of the capacitors with cans, which is more expensive but preserves the original layout. If you put the new caps underneath, you can leave the originals, unconnected, on top. It is more difficult to mount caps underneath but it is certainly doable and I had done several that way. What you save on the new board, you more than make up with time spent. Everyone's equation of time vs cost is different...

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

Sent with secure email.

On Monday, January 27th, 2025 at 12:22 PM, DavidC KD4E via <qrv=[email protected]> wrote:

I don't understand the 'cage' thing.

There a solid metal plate over the bottom of this PS.

Thanks

On 1/27/25 11:52, Evan via wrote:

As a side note, some prefer the AC-3 over the AC-4 due to the "open air" sort of cooling while the AC-4 has a small number of "hot air exhaust slots". I have no personal experience with the AC-3 so I am not aware of reliability versus the AC-4.

On Monday, January 27, 2025 at 11:47:12 AM EST, Steve Wedge, W1ES/4 via <w1es@...> wrote:

I would simply go ahead and re-cap this supply. Paper bodied electrolytic capacitors are prone to dry out.

If you want to wait, replace just the bias supply’s capacitor, as if you lose your bias supply, your finals, at best, will be stressed beyond their ratings, shortening the life of the tubes.

The rebuild kit for the AC-3 costs more than the one for the AC-4 because it needs a “cage” over the board to prevent contact with dangerous voltages. It is well worth it, though.

Steve Wedge, W1ES

Time flies like an arrow. Fruit flies like a banana.

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On Mon, Jan 27, 2025 at 10:54, DavidC KD4E via <qrv@...> wrote:

I accepted a trade offer of a TR-4 for my troublesome TR-3.

Opened things up and have a few questions for those in the know ...

Images here:

The power supply has some sort of filmy deposit on top - I'm thinking

it's residue from tobacco.

1. I'm real shy about putting moisture on the tops of the paper
electrolytics

but would WD-40 or a citrus-based cleaner using a q-tip be safest for the

chassis?

2. Do the caps appear to be original? (The rig works but I'd rather update

things, if the caps are ancient, prior to setting it up on my operating
desk.)

3. Does the serial number reveal anything useful, please?

Thanks,

David KD4E