VK Logger Ham Radio Forum Archive

Posted: **Tue Jan 15, 2019 9:15 am**

My D-3800 died last night... though, mostly my fault...
It suffered a short circuit on the output of the P/S.

Voltage is no longer regulated, sitting at 21V so I suspect one of the regs. I had some spares but they've been misplaced since the last fix I did to it.

Casualties:
1 x Yaesu FT-8900R (no crowbar circuit protection on this P/S). Little diode gone inside the radio so hopefully will be an easy fix... I hope... D1042 a P6KA18 transient voltage suppressor. Someone mention it's just a fancy name for a 15-16V zener.

1 x D3800 P/S

Near Misses:
FT991 - funny enough it powered down, I got the output off the radio quickly... massive panic set in... reconnected it to a battery and it powered up like nothing had happened. Phew!

Moral of the story - install protection on the P/S output... aannnnndd don't leave croc clips plugged in!!!!

Posted: **Tue Jan 15, 2019 1:31 pm**

After you fix your supply you need to put something like this circuit between the power supply and the rig .
I only use the over voltage part of this circuit on my D-3800 supply.

Cheers
Ken

Posted: **Tue Jan 15, 2019 1:44 pm**

Thanks Ken,
Yes a right pain.

Hayden

Posted: **Tue Jan 15, 2019 2:03 pm**

Thanks for that Ken.

I'll be assembling one as soon as the weather allows me back into the 'man cave'.

Cheers

Posted: **Tue Jan 15, 2019 2:42 pm**

When you fix your supply I would suggest that you place a resistor (SOT) across TR7 so that the fan runs very slow all the time.
This stops the annoying fan from coming on at full speed when you only have a receiver running.

Cheers
Ken

Posted: **Tue Jan 15, 2019 2:50 pm**

The amount of DX I've probably missed because of that fan....

I'm going to get a few 2N3055's today.. see which one has blown.

Regards
Hayden

Posted: **Tue Jan 15, 2019 4:05 pm**

I made a video on repairing one of these power supplies.

https://www.youtube.com/watch?v=plA_8Erz3R4&t=861s

Brendan VK3MH

Posted: **Tue Jan 15, 2019 6:08 pm**

put a 17 volt idiot diode across output
even old cbs have the $1.50 avalanche device acts as a crowbar

Posted: **Wed Jan 16, 2019 11:26 am**

Close shave on the FT-991!! That was some serious good luck!

Posted: **Wed Jan 16, 2019 11:28 am**

VK2LK wrote:Close shave on the FT-991!! That was some serious good luck!

Maybe they are built better than we thought - although I'm pretty sure the 8900 took one for the collective Yaesu team

VK Logger Ham Radio Forum Archive

DSE D-3800 P/S

DSE D-3800 P/S

Re: DSE D-3800 P/S

Re: DSE D-3800 P/S

Re: DSE D-3800 P/S

Re: DSE D-3800 P/S

Re: DSE D-3800 P/S

Re: DSE D-3800 P/S

Re: DSE D-3800 P/S

Re: DSE D-3800 P/S

Re: DSE D-3800 P/S