| Author |
Message |
    
Troyota
Junior Member
Username: Troyota
Post Number: 38
Registered: 4-2004
| | Posted on Wednesday, August 26, 2009 - 11:49 pm: | 
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i bought a tram d201 23 channel. it looks great and worked great with outstanding receive and transmit. i have had it a month or so now. i hooked it up last night and talked on it and got great audio reports as always.
anyway i got busy doing paperwork and was just letting it sit there and receive. listning to the locals, then all the sudden it went quiet, i looked up and it was not on anymore. so i checked the rear fuse and it was blown, so i put another in it and it blows it instantly.
i have checked all tubes with a tube tester for shorts and emmission. all are good no grid leakage either. looking at the board i see no apparent damage, or burnt components. not really familiar with these old rigs, so all help is appreciated. any ideas that come to mind?
thank you |
Tech833
Moderator
Username: Tech833
Post Number: 1726
Registered: 8-2002
| | Posted on Thursday, August 27, 2009 - 12:20 am: |
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It's not a tube.
My guess is the power supply filter capacitors went leaky or shorted and took out the rectifier bridge. Rectifiers fail shorted most of the time, and that will take a fuse in nanoseconds. I'll cross my fingers that your power transformer is not damaged.
Electrolytic capacitors have a working life that equates to about 10 years. After that, you are always on borrowed time. ALL electrolytic capacitors in tube gear should be replaced before the equipment is put into daily use. |
Troyota
Junior Member
Username: Troyota
Post Number: 39
Registered: 4-2004
| | Posted on Thursday, August 27, 2009 - 9:46 pm: |
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first off thanks for the reply. here we go. with the ba board out, still blows fuse. with all tubes removed still blows fuse. i did notice on the small cable inside (rca cable on one end) the end that goes to the top of the crystal channel selector shows shorted with continuity tester. i can unplug it and the crystal channel connector board tests good, (no continuity) the cable still tests connected tho. i have looked around on the board but no visible problems. on the power supply filters are they the large caps in front of the tranformer? where is the rectifier bridge? sorry im so ignorant on this old anchor, but im trying to learn. thanks for the help so far guys any more thoughts? |
Tech833
Moderator
Username: Tech833
Post Number: 1727
Registered: 8-2002
| | Posted on Saturday, August 29, 2009 - 6:52 pm: |
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If it still blows the fuse with all tubes removed, focus on the power supply.
The large capacitors near the power transformer are most likely the filter capacitors. Replace those for good measure.
The rectifier bridge could also be some individual diodes, I have never been inside a Tram D201 before, so I am not sure. Either way, they will be the diodes or bridge connected to the transformer secondary leads or terminals. If individual, there should be 4 of them. Check them all. Use a voltmeter with a diode check capability. Using a simple ohm meter won't work because it doesn't put out enough voltage to bias them for a good test. |
Teham
Intermediate Member
Username: Teham
Post Number: 120
Registered: 1-2004
| | Posted on Thursday, May 05, 2011 - 2:11 am: |
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Replace all the bridge diodes and caps. even if the show good there is a good chance they will faail. tony/n5jva/cef 259 |
Kd0gye
New member
Username: Kd0gye
Post Number: 1
Registered: 12-2013
| | Posted on Tuesday, January 08, 2019 - 8:23 am: |
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Check bridge rectifier , it is most likely shorted. |
