Author Topic: Repairing the Humidity Sensor on a HeathKit ID-5001  (Read 357 times)

0 Members and 1 Guest are viewing this topic.

Offline HCMP

  • Member
  • *
  • Posts: 2
Repairing the Humidity Sensor on a HeathKit ID-5001
« on: November 16, 2021, 04:01:55 PM »
All, This is my first public post to the forum. I was encouraged to share the following by one of your esteemed senior members. So, for what it's worth...

I am in the process of trying to resurrect a 1990-era ID-5001. The outdoor humidity sensor after getting dislodged and hanging fully expose to the weather for at least ten years was in a very sorry state and certainly didn't work. Visually, apart from rust and dirt, the only obviously dead component was D701 (see attached circuit diagrams) the body of which was in two pieces. Replacing this was fairly straightforward the only challenge being getting clean surfaces to solder to without destroying the foils which in many place showed signs of lifting, Very fine emery paper and liquid flux were very helpful.

The circuit still did not work. I then spotted and purchased a working 1980s-era  Heathkit Relative Humidity Indicator ID-2295.  This had sensor enclosures which looked identical to mine. I hoped that the sensor units, if not the same, would be close enough that the variation in calibration ranges might allow me to get it to work with my ID-5001. Unfortunately, I could not get it to work.

With an oscilloscope I was able to see that the reference oscillator in the original (weathered) sensor was running nicely at about 10kHz. However the oscillator containing the humidity sensor (A701) was not. However putting either the 110pF calibration capacitor across pins E & F or adding the 42pF to pins H and G woke things up nicely. Adjusting the trimpot R704 did nothing. Replacing the trimpot was straightforward. Fortunately, the capacitative humidity sensor  used in both ID-5001-1 and ID-2295 is identical (Heath p/n 473-32). Thus, with care, I was able to remove the sensor from one of the ID-2295 circuits and fit it to the one feeding  the ID-5001, It is working very nicely at the moment!

I have attached copies of the circuits for the sensors for both the older id-2295 and for the id-5001-1. it is interesting to see how the circuits have evolved although the basic operating principle for each remains the same. Also, a picture of the defunct sensor removed from my unit.

i hope that this may be of some interest and would be happy to answer questions or elaborate.

Offline dupreezd

  • Forecaster
  • *****
  • Posts: 505
Re: Repairing the Humidity Sensor on a HeathKit ID-5001
« Reply #1 on: November 16, 2021, 06:18:17 PM »
Replacing this was fairly straightforward the only challenge being getting clean surfaces to solder to without destroying the foils which in many place showed signs of lifting, Very fine emery paper and liquid flux were very helpful.

To clean edge connectors, especially gold plated one, use an eraser. The white ones are very delicate and will not remove or scratch the gold plating, while the ones on a pencil (pink ones) are a bit more abrasive.
Davis VP2 6163 | WiFi Logger
CWOP - FW0717
Blitzortung 2100

Offline WA7FWF

  • Contributor
  • ***
  • Posts: 142
  • Blitzortung 1196
Re: Repairing the Humidity Sensor on a HeathKit ID-5001
« Reply #2 on: November 16, 2021, 09:47:27 PM »
Well Done!
  AH the good old Phillips H1 humidity sensor. Several years back I was buying up ID-5001s and 4001s to repair and sell on eBay, I even made a circuit board and sold a few humidity kits to replace the guts in failing ones. There was a company in England that still had the H1 sensors and I bought a batch from them.

 There is also a later version Heathkit did that used a different sensor, pretty rare as I have only seen pictures of them.
 [ You are not allowed to view attachments ]

Glad to see someone else keeping the old Heathkits running.
Kevin

Offline Kev

  • Senior Member
  • **
  • Posts: 60
Re: Repairing the Humidity Sensor on a HeathKit ID-5001
« Reply #3 on: January 29, 2022, 08:52:11 PM »
The Phillips H1 is actually still being manufactured, just not by Phillips anymore. They're readily available new, made by Vishay.
https://www.mouser.com/ProductDetail/Vishay-BC-Components/238169190001?qs=sGAEpiMZZMsJEQNpvQJiZ4QV0%2FFDH9E0
« Last Edit: January 29, 2022, 09:14:10 PM by Kev »
Heath ID-5001-C Advanced Weather Computer (1990)
Texas Weather Instruments WR-25 (1998)

Offline DaleReid

  • Forecaster
  • *****
  • Posts: 1843
    • Weather at Eau Claire, WI
Re: Repairing the Humidity Sensor on a HeathKit ID-5001
« Reply #4 on: January 30, 2022, 08:51:25 AM »
What a great project and your knowledge of electrical circuits combined with persistence has given you a working sensor.

This forum has been a place to share and archive information just as  you've shared to allow even relatively rare equipment to be talked about and fortunately share how it was done for others to try to keep older stuff going.

It isn't easy, and at times a very shame that otherwise good stuff becomes 'junk' when replacement parts or sensors are not available.

I hope you get other notes of thanks for the sharing, and that some can use your careful work to keep a few of these old units still working.
Dale
K9ELD
ECWx.info
&
ECWx.info/t/index.php

Offline HCMP

  • Member
  • *
  • Posts: 2
Re: Repairing the Humidity Sensor on a HeathKit ID-5001
« Reply #5 on: February 13, 2022, 02:21:33 PM »
The Phillips H1 is actually still being manufactured, just not by Phillips anymore. They're readily available new, made by Vishay.
https://www.mouser.com/ProductDetail/Vishay-BC-Components/238169190001?qs=sGAEpiMZZMsJEQNpvQJiZ4QV0%2FFDH9E0

This is really good to know. I searched high and low but could only come up with "item no longer manufactured". Many thanks indeed for sharing you knowledge!

Offline mldenison

  • Contributor
  • ***
  • Posts: 111
    • York, PA Weather
Re: Repairing the Humidity Sensor on a HeathKit ID-5001
« Reply #6 on: February 13, 2022, 02:59:25 PM »
I still have my 5001.  Unfortunately, I had a brownout then a power surge quite a few years ago.  The console was dead.  I suspect it's the power transformer.

The rain gauge rotted away some years ago and the anemometer also dissolved as well.  I believe I have the temperature sensors and cable.

It's a shame as it was/is the best display I've seen over the years.
Windows 7 x64
Weather PC: Intel NUC
Davis Vantage Pro 2
Weather Underground: KPAYORK30
York, PA Weather (Saratoga)
York, PA Weather (Leuven)
York, PA PWS Station