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PostPosted: Tue Oct 03, 2017 4:10 pm 
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Joined: Mon Sep 04, 2017 7:39 am
Posts: 3
Hi, I just assembled the Hardrock 50 and I did the three ohmmeter tests. Step 1 and 3 are ok, but step two failed, with the power switch "on" the resistance between the red powerpole measured on the reminal block 45° and ground shows 0 Ohm. What shall I do?
Jurg HB9AWJ


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PostPosted: Wed Oct 04, 2017 5:18 am 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1143
Hi Jurg,

There seems to be a short between the 13V rail and ground. The first thing to do is figure out which board it's on. Unplug the front panel and measure between the 13.8V test point and the ground test point If this is shorted, then the problem is on the control board.

Since the control boards are fully tested, the only place the builder could cause a short would be on the 20 pin header.

More likely, the short is on the amp board and will still show shorted with the front panel removed. Every relay has one pin connected to 13.8V so check around the pins for bridges. The temperature sensor is another place that is easy to create a solder bridge. Check the 20-pin header.

The PCBs are supposed to be electrically tested but we did find one earlier this year with a short under one of the relays. As soon as we discovered the issue we started chacking all of the boards and we haven't found any others. But if you closely look over everything and don't find the short, you may need to send the effected board here so I can find it.

Normally I'd recommend sending the entire amp but international shipping and customs fees and delays might prevent this.

73,
Jim WA2EUJ


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PostPosted: Wed Oct 04, 2017 9:53 am 
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Joined: Mon Sep 04, 2017 7:39 am
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Hi Jim, thank you for your fast answer. I detached the front panel and checked the amp board seperatly. As you said, the short remained also without front panel. I checked all soldering points, especially with the relays, the 20 pin header and the temp sensor. I used for the control (also for soldering) medical eye mag loups (as ENT surgeon I am used to work with microscops and eye loupes), but I cannot find any solder-bridge. Shall I remove the temp sensor and test again? Shall I remove all relays (would be difficult) or shall I send the board to you?

73, Jurg


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PostPosted: Wed Oct 04, 2017 7:11 pm 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1143
Hi Jurg,

The last one had the problem under RLY-15 and a hot-air station is what it takes to get the relays off. Another trick is to use a high current supply and run 5 or 6 amps through the short then use a thermal imager to see where the current is flowing. Infrared light does show up on Cell Phone cameras (try looking at your TV remote through you cell phone camera and press a button) you might be able to observe the traces that are heating. You could also snap a picture and send it to me.

73,
Jim WA2EUJ


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PostPosted: Sun Nov 26, 2017 10:17 am 
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Joined: Mon Sep 04, 2017 7:39 am
Posts: 3
Hi Jim

Thank you for your help to find the defect which caused the short on the pcb (finally found under relay 15), for the repair and quick shipping back and for the check of the amp and ATU. The HR50 works now perfectly.

First I had some problems with interfacing the HR50 to the PowerSDR software (OpenHPSDR mRX PS v3.4.2) which controls my ANAN-10. In the operating manual I found it finally under Flexradio Flex-1500 (which uses also OpenSDR) and the important thing is to check the "Allow Kenwood AI Command box" and to use the the same baude-rate as is used for usb-connection in the HR50. For the PTT control I use the physical connection, which on the ANAN-10 side has to be connected to the PIN 2 and PIN 25 (just as information if someone else need to know how the connection has to be made).

73, Jurg


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PostPosted: Wed Mar 07, 2018 8:50 pm 
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Joined: Thu Feb 08, 2018 12:39 am
Posts: 15
Hi Jim.

I have the exact same problem with step 2 failing with ~1ohm between 13.8_SW and GND.

I attached a current limited supply at 2-3A and two different routes light up. The first is the trace from the power terminal block through pin 1 of J1 and on to pin 1 of RLY14 and RLY15. (shown in photo)

The next trace that lite up was the segment going to C56 and to the power pin of U3(pin 10). (shown in second photo)

QSK and Display board removed.
Power switch pins shorted.
RLY15, C56 were removed in the photos.
U3.10 pin was lifted off the board.
Still a power/gnd short.

I'm wondering if this is a 4 layer board because the temperature gradient stops at those pins. Are there internal traces? I wonder if it would be more evident in the gerber files.

Any thoughts on where else to try? I've scanned the board with microscope and can't find anything.

Scott

It looks like the forums aren't taking images. I posted them here too.
https://drive.google.com/open?id=1TQRKP ... yTZ9WZL5Dg
https://drive.google.com/open?id=1OaY8X ... iTJgKwZUYC


Attachments:
2.jpg
2.jpg [ 34.03 KiB | Viewed 5943 times ]
1.jpg
1.jpg [ 121.66 KiB | Viewed 5943 times ]
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PostPosted: Thu Mar 08, 2018 6:29 am 
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Joined: Mon Jul 23, 2012 6:25 am
Posts: 1143
Hi Scott,

The PCB is only 2 layers. The manufacturer palletized the PCBs and only 1 of 12 boards has the issue (we think) we've eliminated the short from all of the boards in out shipping stock I most of the ones that have shipped are accounted got.

The short is under RLY-15 between pin 1 and the ground plane. If you have RLY-15 installed, the short isn't visible.

I don't have any luck posting pictures here but if you send me an email jim (at) hobbyPCB (dot) com I can send you a photo.

You can decide if you want to tackle the issue or send it to me.

73,
Jim WA2EUJ


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PostPosted: Mon Mar 12, 2018 4:35 pm 
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Joined: Thu Feb 08, 2018 12:39 am
Posts: 15
Just as a followup, per guidance from Jim, I found that my board had a short between Relay 15 pin 1 to the adjacent ground fill. This was located under Relay 15, so it had to be removed.


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