Minitor Motorola Minitor II (2) Crystal Removal/Desoldering & Replacement

[trp2525]

I am in the process of changing out the 2 crystals in a Minitor II SV VHF-High pager. From what I have researched and seen, the PC board traces on the top side of the RF board are very delicate and can be easily damaged during a crystal pull especially if you use excessive heat or force to remove the crystal.

I have received some advice from a person very experienced in Minitor II crystal pulls. The way he does it is to initially add some new solder to the crystal connection points on the underside of the board. He then heats up one connection point at a time while gently pulling on that side of the crystal with his thumb and forefinger. He repeats this heating and pulling procedure on each leg of the crystal (essentially "rocking" the crystal from the board little by little) until the crystal is totally free from the board. He then uses a solder vacuum to clean up the holes in order to put in the new crystal(s).

Is there anyone here who has done this Minitor II crystal removal and replacement previously and who can offer any additional personal pearls of wisdom, comments or suggestions? I'd rather learn from the "experts" on this Motorola board first before my making any rookie mistakes.

The reason I am attempting this on an old Minitor II is so that I can monitor (in CSQ) my local fire department's VHF-High channels 1 and 2 in a very small form factor receiver. I was lucky enough to obtain the 2 necessary crystals and also picked up some brand-new Minitor II NiMH rechargeable batteries from Power Products. I don't need any Permacode active filter paging components as my local fire department does not do any type of two-tone alerting on either frequency.

 

[gary123]

My experience is that the method you describe of using fresh solder on the pins and then gently prying up the once side and then the other while heating the associated pin is the best way. Once the crystal is out use solder remover to clean the holes.

getting crystals is getting harder and harder. You may want to consider upgrading to a programmable minitor 4,5 pr 6. The programmer socket for the minitor 5 are getting harder and harder to find. A brand new minitor 7 is not worth the expense as feature for feature its identical to the minitor6.

 

[trp2525]

...getting crystals is getting harder and harder. You may want to consider upgrading to a programmable minitor 4,5 pr 6...

I was lucky that I was able to get the 2 Minitor II crystal frequencies that I needed. They were from used equipment pulls but were tested before being sent to me.

Out of all the Minitor pagers Motorola has manufactured and/or sold, IMHO the Minitor II was the best one. I have one that I purchased brand-new directly from Motorola back in 1988 and it is still in perfect working order today. It never misses a tone-out, has clear audio, great sensitivity and more than sufficient audio volume even with the slight reduction due to narrow banding. YMMV

 

[richardbritt]

I am a fan of the original Minitor pagers (the brick). But parts and lack of crystals have mine sitting on my shelf with my Motorola alert monitor. The person asking about soldering can get a used Minitor 3 or 4 cheaply on ebay for $50 with a charger if you are patient. I often buy them for volunteer fireman in my area who want a 2nd pager. A programming cradle can be made out of a old charger, interfaced using a radio shack scanner programming cable. I made one for Minitor 3/4 and also for the 5s.

Have fun. The older pagers and monitors are fun to get working

Regards Richard

 

[buddrousa]

I still have a full set of Motorola Reeds for 2 Tone

 

[trp2525]

...The person asking about soldering can get a used Minitor 3 or 4 cheaply on ebay for $50 with a charger if you are patient...

My total expenditure for the used Minitor II SV pager (which was in excellent working and cosmetic condition), the 2 crystals that I needed (both purchased from used equipment pulls) and 2 brand-new NiMH batteries was $42. I didn't need a charger as I already had a like-new Motorola Minitor II amplifier/charger with a VHF-High antenna from another Minitor II that I already owned. Also, there was no need for any Permacode Active Filters to be installed as my local fire department does not do any 2-tone alerting.

After installing the 2 new crystals the pager is working great with good sensitivity and audio volume. I didn't need to re-tune/re-align the pager as the 2 crystal frequencies that I installed were very close to the 2 original factory frequencies. Overall I am very satisfied with the results for the little money I spent. Hopefully new replacement batteries will continue to be manufactured for the Minitor II pagers so that we can keep these workhorses going.

 

[richardbritt]

Sounds awesome! Nice job