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 Post subject: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Nov Tue 24, 2020 1:51 am 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 2115
Location: Weimar, Texas
Rather than embed an image that exceeds the limits or provide a schematic that's too small to read, here's a link to the schematic, failed parts circled in red:

https://wildlightimagingstudio.com/img/ ... 0902-6.jpg

The parts list calls them Fuse Resistors. Mouser and Digikey don't understand "fuse resistors" but considering the fast rate that parts are becoming obsolete, I'm not surprised.

They are 5.1 ohm 1.6W ceramic resistors. They worked... both are open.

Image

I found some 5.1 ohm 5W wirewound resistors on Mouser but there is a 100 count minimum order

Anyone know of a source for these. I don't think Yaesu is going to be able to help but I will give them a try...

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 Post subject: Re: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Nov Tue 24, 2020 2:27 am 
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Location: Mountains of Mourne. Ireland.
TYPE RXF/RYF - THERMAL FUSIBLE RESISTOR
Wirewound, Metal Oxide Stand Up Fusible Resistor, Ceramic Case.
https://microohm.com/wwfuse/rxf.html

Image Image


A53K5R1J in your parts list looks like a UCHIHASHI part number.
(5.1Ω 1.6W) data sheet: https://eu.mouser.com/datasheet/2/400/d ... 525804.pdf

from: https://eu.mouser.com/Passive-Component ... mal%20fuse


(google search for) different part number A5MC-5R1J
or see uchihashi.co.jp
https://www.google.com/search?q=a5mc-5r ... QQ_AUICCgD

Yaesu US should have them.
Greg.


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 Post subject: Re: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Nov Tue 24, 2020 2:33 am 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 2115
Location: Weimar, Texas
Never mind. I checked Newark, they had an alternate part number but none in stock, back to Mouser and they had them in stock. Now to try to figure out why they popped. I was load testing the PSU after repair with a Rigol DL3021A and they went at a very low output current on the higher voltage side (or I screwed up which is possible).

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 Post subject: Re: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Nov Tue 24, 2020 2:37 am 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 2115
Location: Weimar, Texas
egg wrote:
TYPE RXF/RYF - THERMAL FUSIBLE RESISTOR
Wirewound, Metal Oxide Stand Up Fusible Resistor, Ceramic Case.
https://microohm.com/wwfuse/rxf.html

Image Image


A53K5R1J in your parts list looks like a UCHIHASHI part number.
(5.1Ω 1.6W) data sheet: https://eu.mouser.com/datasheet/2/400/d ... 525804.pdf

from: https://eu.mouser.com/Passive-Component ... mal%20fuse


(google search for) different part number A5MC-5R1J
or see uchihashi.co.jp
https://www.google.com/search?q=a5mc-5r ... QQ_AUICCgD

Yaesu US should have them.
Greg.



I guess we were typing at the same time. That's exactly what I bought :)

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 Post subject: Re: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Nov Tue 24, 2020 2:53 am 
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Joined: Jan Tue 31, 2012 1:55 am
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Location: Mountains of Mourne. Ireland.
I know, my grandmother can suck eggs too. lol

power supply fuse resistors blowing
https://www.google.com/search?q=power+s ... wV6BAgUEAE


Greg.


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 Post subject: Re: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Nov Tue 24, 2020 3:16 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3618
Location: Monterey California USA
So...you have found these fusible resistors are open but you have not found out why yet? They opened because something is shorted or at least drawing way too much current.

This is the usual switcher power supply used in modern ham gear. The most common issue on a dead supply is usually dried out electrolytics, which you find with an ESR meter. But that usually just prevents the supply from "starting up" and doesn't blow fuses.

In this case, suspect blown high current semiconductors and diodes. In factory service centers we used to use Huntron Trackers to quickly look at every semiconductor for shorted junctions, but I suspect you don't have one. When I left the ham radio business in the late 1980's the manufacturer service centers were considering the switching supplies a replaceable part and not component level serviced, and they would not pay us to fix them, so we stopped. They are of course fixable if you know what you are doing, but the time charge eats up warranty profit so they stopped allowing us to do it. Things may have changed by now.

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 Post subject: Re: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Nov Tue 24, 2020 3:54 am 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 2115
Location: Weimar, Texas
Geoff Fors wrote:
So...you have found these fusible resistors are open but you have not found out why yet? They opened because something is shorted or at least drawing way too much current.

This is the usual switcher power supply used in modern ham gear. The most common issue on a dead supply is usually dried out electrolytics, which you find with an ESR meter. But that usually just prevents the supply from "starting up" and doesn't blow fuses.

In this case, suspect blown high current semiconductors and diodes. In factory service centers we used to use Huntron Trackers to quickly look at every semiconductor for shorted junctions, but I suspect you don't have one. When I left the ham radio business in the late 1980's the manufacturer service centers were considering the switching supplies a replaceable part and not component level serviced, and they would not pay us to fix them, so we stopped. They are of course fixable if you know what you are doing, but the time charge eats up warranty profit so they stopped allowing us to do it. Things may have changed by now.


I was load testing it when it popped. I had already pulled and checked the electrolytics with an Agilent U1733C. All looked great. When on test, voltage was good and I was slowly increasing current when the two resistors started smoking. I couldn't shut down fast enough. The repair I made was simple. I cleaned the old solder off of the DC terminals (the solder was cracked and one terminal could be pulled out) and resoldered the DC output terminals. I've since checked the TRIAC and a few other components and they seem to be fine.

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It's hard to solve an equation if every term is an unknown.

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 Post subject: Re: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Nov Thu 26, 2020 8:31 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: dayton oh usa
thats the soft start.
those resistors get bypassed once the unit is running.
the scr fires when the voltage from d12 comes up.


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 Post subject: Re: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Nov Fri 27, 2020 1:07 am 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 2115
Location: Weimar, Texas
kc8adu wrote:
thats the soft start.
those resistors get bypassed once the unit is running.
the scr fires when the voltage from d12 comes up.


Thank you. It was right in front of me but I didn't see it until you pointed it out.

I think I had the load on the 13.8V line. The Vreg is only good for 3A but I think the load was at or below 3A. It's been too long since I did the test to be sure. Idk... what fried the resistors.

PSU ratings
DC Output Voltage: +30 V , +13.8 V.
DC Output Current: +30 V: 15A; +13.8 V: 3A.

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It's hard to solve an equation if every term is an unknown.

73
NE5U

Mike


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 Post subject: Re: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Dec Tue 01, 2020 2:09 am 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 2115
Location: Weimar, Texas
kc8adu wrote:
thats the soft start.
those resistors get bypassed once the unit is running.
the scr fires when the voltage from d12 comes up.


Well, the new resistors came in and I installed them. They popped when the load got to 7-ish amps. The PSU is rated for 30V 15A on the side I was testing. My load tester is only rated for 200W so I wasn't going to go much higher. I should've been watching the temperature on those resistors. I have extras so that's not an issue. The SCR/Triac/Thermistor is dead. I pulled it put it in a little breadboard circuit and it won't light a 12V lamp when I switch it on.

BTW - I know they aren't the exactly same, well.. thyristor and SCR are, but I have three different datasheets that call the part 3 different things. That's why I listed them that way. Mouser says it's an SCR and -

BT151X-800R,127 Cross Reference Match For: FS1209NW TF861S. Subcategory Thyristors

TF861S is what is on the schematic. The device has M1661S on it.

The switching transistor tested good. Waiting on parts once again...

_________________
It's hard to solve an equation if every term is an unknown.

73
NE5U

Mike


Last edited by Mike6158 on Dec Tue 01, 2020 3:42 am, edited 1 time in total.

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 Post subject: Re: Yaesu FP-29 PSU for FT1000 MKV
PostPosted: Dec Tue 01, 2020 3:07 am 
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Joined: Dec Wed 24, 2014 7:34 pm
Posts: 2115
Location: Weimar, Texas
If you look at the schematic I linked to:

https://wildlightimagingstudio.com/img/ ... 0902-6.jpg

there's a 1SS270A Silicon Epitaxial Planar Switching Diode in the line from the winding on the transformer to R5 (on the phase dot). The other side of the transformer is tied to the cathode of the SCR. The diode doesn't exist and there's no place to install it. I've read that missing components are "normal" for this supply because there were numerous versions of it.

I'm not going to worry about it but it makes me wonder if the schematic I'm looking at is a newer or older version.

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