Tram D201A smaller power transformer vs D201

[mark4]

The Tram D201 power supply transformer some say is 33% smaller. I don’t know if that’s correct I haven’t measured it.
I find postscthat state right before Tram was going out of business they were trying to cut costs and downsized the transformer.
Well that’s not really the case at the point in time when the D201A came out. The CB boom was still big and the downsizing of the transformer was not because the doors were closing.

As for the size of the transformer it sure seams to be sufficient. Was it here some design or material change that made it more efficient?
This maybe one for 2600 or knowledgeable tech.

[2600]

Pretty sure it's a difference in the steel alloy used for the core laminations. The traditional "high silicon" steel was giving way to a (then)-new alloy called "hypersil". I always thought that this stuff was used only for type "C" and "R" transformer cores made from steel tape, and not the "economy" (E-I) core used in this transformer. But if you looked inside of home appliances that used AC brushless motors in the late 70s and 80s, the size of the cores in those was shrinking from year to year for motors of the same rating. And that was the explanation I got for that at the time, improved steel alloys in the motors' cores.

Magnetic components are not something I have any design experience with, but that's the closest I can come to an explanation.

73

[mark4]

Thanks for the information. I just come across these posts ancient or new. And just a short read reveals it’s opinion more than fact.
Stories of D201A transformers burning up because they claim the transformer was 33% smaller and 33% less powerful.
I have not come across this issue at all. Except for the fact of the line to ground capacitor on the AC socket shorting out and setting the transformers paper wrapper on fire.

[Sandbagger]

Dec 21, 2017 0:45:16 GMT -5 mark4 said:

Thanks for the information. I just come across these posts ancient or new. And just a short read reveals it’s opinion more than fact.
Stories of D201A transformers burning up because they claim the transformer was 33% smaller and 33% less powerful.
I have not come across this issue at all. Except for the fact of the line to ground capacitor on the AC socket shorting out and setting the transformers paper wrapper on fire.

Ah! I always wondered why the paper wrapper of both of my D201's transformers were burned, yet there was no sign of overload to the transformer or other circuit damage.

[mark4]

Oh yeah, I have parts cars with the caps that have shorted out setting the transformer paper on fire. As you know if it’s plugged in it’s always seeing the line voltage. I replace these with modern safety bypass caps. I also install across the line rated safety cap. It suppose to suppress line noise. Can’t say I notice a difference. But most noise is coming from your antenna anyway.

[Sandbagger]

Dec 21, 2017 10:26:57 GMT -5 mark4 said:

Oh yeah, I have parts cars with the caps that have shorted out setting the transformer paper on fire. As you know if it’s plugged in it’s always seeing the line voltage. I replace these with modern safety bypass caps. I also install across the line rated safety cap. It suppose to suppress line noise. Can’t say I notice a difference. But most noise is coming from your antenna anyway.

I guess the previous owners of mine simply cut the bad caps out when they blew. I don't have any at all on mine. I was thinking about simply replacing the stock AC sockets with IEC sockets with internal filtering.

[2600]

Here's a particularly photogenic D201 Surge-Arrest capacitor. Pyrotechnic type A. This one didn't quite set the transformer paper to smoldering. Must have flamed out too soon.



More than once I have shown this "feature" to a Tram owner when I removed his bottom cover. One of them was initially horrified, until I assured him the damage was only cosmetic. When I asked "Do you remember coming home and smelling something burned one night during storm season? And you never did track down where the smell came from?"

At least one customer nodded with a faraway look as if this explained something that had puzzled him until now.

But yeah, this capacitor serves to keep RF INSIDE the radio. Isn't really meant to keep RF interference out, so much as to reduce the transmit signal that will "escape" from the radio out the power cord.

It's been a dozen or more years since we bought the (expensive) punch to mount IEC sockets easily. The filtered sockets go cheap if you shop around. And no more lost power-cord problems.

73

[Sandbagger]

The self destructing cap in mine did a little more damage. But the offending part was removed long before I got it and replaced with different caps.

[wildcat444]

What are the parts we should replace them with? I am about to start a restore on mine soon. Should be three caps total to meet current standards as I understand it?

If I have this correct, you replace the three lead Z5U rated 1KV ceramic surge suppressor on AC jack to two separate .0047uF 275V X1Y2 safety rated disc capacitors (one on neutral pin of the jack to ground and one on hot pin of jack to ground) and then a third one, a .047uF 275V X2 rated across the neutral and hot (or is it a .1uF across neutral and hot?).

Are the values I stated correct and where they go correct? Any info on how to find them at Mouser or the best parts types to use?

Thanks!

[mattbee]

Good morning,

Here is the replacement safety capacitor i use.  

There are TONS of different ones available to use, I just chose these, no specific reason other than the high voltage rating!

Thanks,

Mattbee

[2600]

The "Y1" and "X1" markings on a disc capacitor indicate that it's tested to be safe for use filtering the AC power coming into a device. A capacitor that fails as a dead short becomes a shock hazard. Pretty sure those ratings indicate the cap is designed to fail as an open circuit.


Here's my preferred solution to the wacky power-cord problem.





This power cord should be easy to find for years to come. Besides, I decided that sending a Tram back home with only a 2-prong power cord was bad policy. This simplifies the upgrade, and comes with all the consumer-product safety approvals stamped on the side of the filter.


73

[wildcat444]

Sept 23, 2020 0:09:53 GMT -5 2600 said:

The "Y1" and "X1" markings on a disc capacitor indicate that it's tested to be safe for use filtering the AC power coming into a device.

Wow, thank you both! Now I am a bit confused about the actual caps I should look for at Mouser... I might be wrong but I thought Mike said in a Tram video that he uses a .0047uF 275V X1Y2 safety rated disc capacitor on neutral pin of jack to ground and one on the hot pin of jack to ground, and a .047uF 275V X2 rated across the neutral and hot pins of the jack (or a .1uF across neutral and hot?).

So three caps total to safely protect and filter RF? Should all three caps be X1 and Y1 rated? Are these uF values correct? I tried searching "Safety caps" at Mouser, but I'm having a hard time figuring out what to plug in to their search filter to find the correct caps.

[mattbee]

Mouser Safety Capacitor