Radio Tech (1 Viewer)

[Engineer8000]

Finished these today and sent them home.

The radio on the left is a CR-261TE (86120-35025) used 7505 to 7806 based on the info I could find. Panasonic used screen printed resistors with plated through vias (PTV) or holes in these, cutting edge in 1975. Tough to troubleshoot even with a schematic. The PTVs develop circumferential cracks (barrel fatigue) and can open circuit intermittently.

 

[ToyotaMatt]

morning Russ ,

Excellent work as usual no doubt ......

i would like to offer up a unique collection of sorts to the cause ........

my life time supply of OEM colored rubber bulb caps

most are green , but i have oem blue , oem fire oarnge , oem yellow too

please let me know and i can them mailed out to Ya ........


also , what is involved in getting my CB40M and a right nice 86120-14480 , in the CUE for a 2nd chance at life ?

the CB40M works but like when we spoke the red LCD read out has burnt out bars ?


let me know the procedure


any pick and pull ash tray lamp sockets soon ..........

 

[ToyotaMatt]

 

[Engineer8000]

 

[Engineer8000]

Working on the CB40M today. Some of the segments on the channel LEDs were not working. The segments in the channel display are controlled by contacts in the channel selector switch, wiping the switch a few times got it to working pretty well. After a bit of run time, found the middle horizontal segment on the second digit was intermittent on all channels that used it (2,3,4,6,8, etc) indicating a bad connection somewhere. Digging further in, found a bad solder connection on the back of the led. All segments working fine now.

This is the rear of the channel switch.

A couple pictures of the back of the led.

 

[Braden620]

Are you an EE?

 

[Engineer8000]

Yes. Currently doing business on the kitchen table until the radio lab is complete.

 

[Braden620]

Sweet! I'm a ME with a radio issue that I believe is mechanical. I have the 75' AM/FM model. The radio was working ok but now will not tune. You can spin the tuning knob and nothing moves. I need to pull it out and inspect it.

Forgive my ignorance, but how does one switch between AM and FM on these things?

 

[Engineer8000]

Pushing an am or fm button will actuate a slide switch inside that changes bands. Your condition is common, it's best to remove the tuning mechanism and clean/lubricate it. Try to keep cleaner and lubricant out of the clutch.

 

[Braden620]

I haven't even thought above removing the radio from the dash. Are there any tips or things to watch out for? Heater box looks to be in the way.

 

[Engineer8000]

You should be able to remove the 2 side screws via the cluster and ashtray holes. If the rear bottom screw is there you may have to drop the heater down. When you get the mechanism out of the case you will see how it operates, where the old grease is, etc. I clean using crc electronic cleaner or similar . Then just re-lubricate and operate the tuning dial and push buttons a few times to verify everything is working.

 

[SteveH]

@Engineer8000. I have a 1974 radio identical to this one: Factor Radio Repair - https://forum.ih8mud.com/threads/factor-radio-repair.1227660/

The radio all works as it should, but I see no evidence of a light bulb inside (it's presumably burnt out) nor can I see how to replace it. There is not an obvious set of screws to remove a cover to gain access to the light bulb. Is one of the covers easier to remove than it appears? I restore antique tube radios and it bugs me that I can't determine the magic screws on this transistorized car radio! Can you indicate which screws in the photos are the ones to remove and get to the bulb?

Thanks - Steve

 

[Engineer8000]

For the 08600-00014, the case will come apart like this, you can see the screw holes in the picture.

The bulb is a wedge base T3.25, the original is a Toshiba 158, but the 194 bulb is the same size and has a much longer rated life. It is rated for about 0.5 watts higher than the 158. Or you could go with an LED bulb that @ToyotaMatt sells.

 

[ToyotaMatt]

@Engineer8000 simply has IT going on ....

wow what a nitch service and skill set here , and what the general standard service the FORUM really needs long term steady

im impressed with his work for me thus far , for my clients via my shop ., SOLID !

Thanks Russ !


mattt

 

[Braden620]

@SteveH I may have a vintage Toshiba bulb if you need it.

Be advised, that in this application the components surrounding the bulb are not heat sensitive. In more modern applications replacing a 158 with a 194 may cause troubles. That extra 0.5W generates a lot of heat.

 

[Engineer8000]

@SteveH I may have a vintage Toshiba bulb if you need it.

Be advised, that in this application the components surrounding the bulb are not heat sensitive. In more modern applications replacing a 158 with a 194 may cause troubles. That extra 0.5W generates a lot of heat.

Like plastic bulb holders for the cluster.

 

[Braden620]

Like plastic bulb holders for the cluster.

I should have said as sensitive. You got me. I was thinking more along the lines of 80's model gauge clusters, or other dash related components that were injection molded and have colored bulb filters. What do you think Mr. EE, 0.5W= 1.6 Btu/hr?

 

[Engineer8000]

My first degree was NE, so how about 3120753181547 MeV/s?

 

[Engineer8000]

I agree the light filters might be a problem. The LEDs that Matt sells are a great replacement if you want a lot more light without additional heat.

 

[SteveH]

@Engineer8000 - thanks - I figured that the power/speaker junction block was directly soldered on (and made cover removal difficult), and not that it had handy wires to allow the cover to come off. Very easy, now that you have shown me how. I have some Toshiba 158 bulbs, so I will stick with the lower wattage bulb here. Thanks to you all for the advice!