Cobra 138XLR question.

[dss56]

Does it blow in SSB? If not, suspect the transformer. If it also blows in SSB, I would suspect the electrolytic by the finals, C179.

If i take the 3 wire plug off the transistor radio will come on and receive like normal. If i plug the plug back on to the transistor the fuse will blow. So Im sure the transformer is good or the radio would not turn on at all.

to answer your question i can only get radio to turn on with the tr25 not connected

 

[brandon7861]

TR24? I thought we were looking at TR25.

The voltage for the finals that comes from the audio transformer secondary is supplied by TR25. If connecting it blows the fuse, there is a short somewhere after it. The suspects are C102, the audio transformer, and C179. You said the finals were good, but you could double check by pulling the two jumpers.

 

[brandon7861]

and if I final didn't go, I don't see how the transformer could have. It's probably C102 or C179.

 

[dss56]

TR24? I thought we were looking at TR25.

The voltage for the finals that comes from the audio transformer secondary is supplied by TR25. If connecting it blows the fuse, there is a short somewhere after it. The suspects are C102, the audio transformer, and C179. You said the finals were good, but you could double check by pulling the two jumpers.

I corrected it i meant the tr 25
I will check c102 and c179

the radio has good receive audio both am and ssb with tr 25 not connected

 

[brandon7861]

I corrected it i meant the tr 25
I will check c102 and c179

the radio has good receive audio both am and ssb with tr 25 not connected

Further evidence the transformer is ok.

 

[dss56]

I corrected it i meant the tr 25
I will check c102 and c179

the radio has good receive audio both am and ssb with tr 25 not connected

Brandon

Happy to report it was C102 i replaced C179 first same and then C102 and now radio back to working.

Thanks so much for the help

 

[brandon7861]

Brandon

Happy to report it was C102 i replaced C179 first same and then C102 and now radio back to working.

Thanks so much for the help

suspect the rest are nearing their time too.

 

[dss56]

suspect the rest are nearing their time too.

This radio was recapped as the caps I replaced are not the normal caps. 1the C102 cap was 1000@50volts. Recapped not by me as the C102 was a large profile cap and I replaced with correct size cap just happened to have some.