COBRA 148 PC 412 ISSUE

[COBRAMAN148]

Radio Make and Model: 1978 -1997 COBRA 148 GTL
PCB Number: PC 412
PLL Number: MB8719
Test gear available: VM METER HP O SCOPE SIG GEN
Symptoms: BLOWN D44

What is working: THE RADIO IS WORKING

What has been tried: REPLACE THE DIODE

Did it suddenly happen ?: After overvolt or shorted transistor.
Anything else that may be of help?: It is a common problem i see all the time when restoring these radio`s. it is supposed to be a bad transistor that makes the diode blow. if you put a new diode in it blows the fuse. the radio works fine with d44 out of it. can you help out rick or anyone. thanks very much in advance.

[ramblingman]

d44 is the anti spiking diode
i would check the big electroylic cap,in the right rear corner of pc board
it will be a 470 mfd @ 10 vdc,i think it is c-135 or 136
anyway if it needs replacing replace with a 470 mfd @ 25-35 vdc

[COBRAMAN148]

nope try again. thanks for the info but there are no caps with any values that are even close to that. i did replace a large cap by the transformer. it was shorted but it still did not fix the d44 issue. those numbers you gave are 2 small caps by the voltage regulator. thanks alot. anyone else?

[ramblingman]

are all the voltages correct at the voltage regulator??

[COBRAMAN148]

Ok i figured out what it was it is a ceramic cap a green one on the right side of the radio right by the audio chip. it was a dead short in the cap that caused the d44 to blow. c 235 is the cuprit. i put a new d44 in and changed the c 235 and it fired right up. no more blown fuse. this is a breakthrough for me. i am very happy that i figured it out.