Cobra Base Power Supply Diode

[LeapFrog]

Cobra CAM 89 Base, very similar to the 139 XLR this one having an older style channel select, no SSB, & yes still a 23 channel radio.



*At first glance it seems as if the unit did not power up, on D.C. or A.C.

I checked a diode on the power supply section before reading the schematic and I got continuity through it both ways so I decided it must be bad, come to find out from reading through the schematic this is possibly a Zener type diode?

*After I changed the diode with a silicone rectifier diode type 4001 I noticed the channel selector light was illuminated (It may have been on & not noticed before I pulled the diode).
I noticed two bulbs had already blown out, so I installed 2 blue light emitting diodes with current limiting resistors.
Are grain-wheat the correct type factory-era replacement bulbs?

I assumed something else was wrong because I had no audio coming through my speaker.
After looking at the caps again and still not seeing any oozing electrolyte or blown tops...
I remember these radios need a microphone attached to receive audio, oh snap!
I plugged in a Cobra 4-Pin and BAM I GOT AUDIO!
Now the audio is not the loudest & I need to replace all the electrolytic caps on this 30+ year old radio to really bring it back to life from the dead, www.cbtricks.com/radios/cobra/cam89/graphics/cobra_cam_89_om_sch.jpg
After looking through and realizing I just changed out a part that was probably good
I have looked all over the bench and cannot find the diode I removed, I need to find a correct replacement!
This diode I removed was the only one laying horizontally (looking at the bezel of the radio) I belive all the others are faced "vertically" in the psu section.

My questions are, will the rectifiying diode suffice for further testing, or will it damage some other component by not allowing the reverse voltage flow?

I want to redo this radio all original
NOS (for diodes and bulbs) or cross-referenced modern equivalents that I can be sure where not manufactured with traditional chinese quality.
I can slowly add the values of all the electrolytics found in the b.o.m. to an online shopping cart but there must be a more convenient way?
I thought about buying an ebay capacitor kit for the 139xlr but I will not put chinese junk caps in this radio.

My issue with the diode is one of these, I will have to take the cover back off and snap a picture so you guys can see the one i'm talking about on a board.
One of these are it...
D16 D17 D18
BZ162
SR1k-2
WZ961
Are any modern replacements for the wz961 diode around? I have found the others available online.
Maybe i'm reading the schematic wrong, the lettering in this psu section is distorted.

I have powered it up with 110 volts alternating current and no issues hve been observed immediately, i'm worried about long term reliability and originality.l
If I power this radio up using direct current with the rear standard "mobile type" plug, do I run any risk associated with having the (wrong) diode installed in the power supply unit, i'm asking some of you gentlemen who have been using/repairing radios before I was born. And I know experience pays dividends here, so anyone please comment on the diode I need.

Thank You, & 73's to you & yours.

-LeapFrog469 in the sand pile waving

 

[loosecannon]

D15 and D16 are your rectifier diodes that are turning AC into DC. they are 100v 1a diodes.
replace them with 1N5401 diodes, they are 3a diodes.
do not replace just one of them, replace both even if one tests good.
also, do not mount them right against the PC board, leave some room for air flow around them by leaving the body of the diode up in the air a bit.


D17 and D18 are indeed zener diodes, and need to be replaced with zener diodes of the proper rating in order for the radio to work right. they act as voltage regulators.

D17, the BZ162 is a 16 volt, 1 watt zener diode. you can use an NTE5075A, or any other 16v, 1 watt zener.

D18, the WZ061 is a 6.2v 1/2 watt zener diode. you can use an NTE5013A, or any other 6.2v, 1/2 watt zener.



you can power the radio from the DC input, and the internal power supply will not be used, but do not plug the AC cord into the wall if you choose to do this.

yes, grain of wheat lamps are original equipment.

hope this helps,
LC

 

[LeapFrog]

Loosecannon,

A Very Detailed High Quality, Timely Spot-on Response.
___[\{ `_,°}"/]______
I Will order some parts now and get this baby to Transmit next, others may benefit from this conversation and data.


By Replacing All The Electrolytic Capacitors With The Equivalent Capacitance Values PLUS Higher Voltage + Higher Heat Specs I am improving the radio unless you are an absolute die-hard and want it 100% original, kind of person. Anyone chime in to correct me if i am wrong on this.

Let us say the original is a 100uf 16v 85c
&
I choose to use a 100uf 30v 115c cap instead (this is a hypothetical value),

[Make sure you are getting them from a Dependable Vendor]

Depending on certain variables these MAY last longer than the original spec ones would due to reduced stressed on the part & due to its higher tolerances and taking into consideration the new part will be able to withstand more abuse overall in the circuit if a part goes awry and the circuit creates an over-volt state, plus any electronic part that can withstand heat better, overall is a plus.