Thursday, March 9, 2017

Inside 1980s Sanyo Radio Alarm Clock

When my Dad was in college in Boston, there was a nearby RadioShack where he got all his parts.
I believe this is one of those purchase from said RadioShack. 
This alarm clock has been in my room (used by my brother) for as long as I can remember. I brought it to college with me as a desk clock. I thought it was a beautiful design, and I liked looking at it when I was working.

Cosmo Model CR 2001A

This past December I believe there was a power surge while we were on break. I came back to a broken hard drive and a busted alarm clock. I attempted to fix it. Here are some pictures of the insides for anyone interested!


There's a 9v battery in case of power outages to keep time.


A warning that I will not heed.


Taking off the front cover



I was stunned when I opened this up. It didn't hit me that in the 1980s, electronics were still very new.


The entire interior was very dusty and fragile.


A better look inside. The speaker is on the top, the clock circuit is on the left, and the AM/FM radio is on the right.



The circuit board for the switches and buttons is screwed to the top cover.


The circuit boards made back usually have phenolic as a substrate


Look at this crazy tuner! A string is wrapped around the potentiometer to move the pointer.



This is such a clever way of making a display.


The wires are kind of messy. Old circuit boards have a lot of smooth traces.


Top view of the radio board.



The clock doesn't display correctly.


I decided that perhaps the problem was in this IC chip.
This is the LM8560, which is used specifically for alarm clocks.


Thanks to eBay, I could buy one of these outdated chips!


I soldered in the new chip. It was painful, I broke several pads.


Notice anything broken? Me neither.


Broken pads are pretty hard to find, especially if you didn't make them. I had to jump some connections.



You also sometimes discover broken components! This capacitor was bulging like crazy and had a broken lead.


It's amazing how components deteriorate over time. There were plenty of resistors that didn't have paint on them anymore.


The college dorm life...

I couldn't fix the alarm clock. Unfortunately, the IC chip was not the issue. I tried tested out the other components.
However, every time I desoldered, tested, or even touched a component, I risked breaking a very delicate and irreplaceable part.

Primum non nocere - "First, do no harm" - from the Hippocratic Oath (??)


I decided that I was probably going to do more damage than help, so I put the clock back together.

At least the radio works!

4 comments:

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  3. Thankyou for posting your works. I have had messed with my 1970s cassette tape recorder circuit board while desoldering. I was 18 that time and didn't know about the desoldering pump. Few of pads were gone. But I found a way to fix it. I used a thin copper sheet cut it precisely to the same track width and pad size. I placed the cut sheet exactly on the missing pad or track area and soldered gently. Now it looks great. The board doesn't have any prints or anything but a very old board. It mostly uses axial capacitors and fully transistorised.

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