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I should start by saying I am a soldering wizard. I have a TS22A manufactured by Harris. The main board in the body of the unit is date stamped in 1995. The board in the earpiece capsule is dated 1996. Upon finding my old unit in the closet, I found that both the 9 V battery and 3 V battery were toast. This is the version that only has one internal lithium cell on the main board. After acquiring a new cell and spot welding new nickel connections on to the 3V battery, I installed it along with a new 9 V battery. Following the replacement, I found that the loudspeaker would only pop when pressing it’s button, where it used to produce three different volume levels of hum when testing while disconnected from a phone line.

On further investigation I found that one of the chips on a daughter board in the earpiece capsule had it’s top sanded off to obscure its identity, and there was a paper label with the letter R attached to it. I know that some Harris TS22* units had a data lockout chip/processor that would seize up when the 3V battery died. I’m not sure if this is one of those units or not. I will be posting pictures of this chip soon. Can anyone here help me identify the chip, or tell me why these symptoms may be occurring? I know some companies offer a $65 service for repair of these units, but if I can get the offending chip (if it is the problem) and replace it myself, I would save a not insignificant amount of money. If anyone would be willing to help me I would be eternally grateful! I’ve had this unit since high school and would love to get it working.

Thank you in advance!
Garbleduser

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The attachment manager for this forum seems to be giving me issues uploading a picture. Here is a link to the picture daughterboard with the chip in question. https://www.dropbox.com/s/nzxu9u0yb32y9cg/IMG_0391.jpg?dl=0

Upon looking closer I noticed that the model number which is stamped into the plastic is TS22A.4, just in case it makes a difference. If anyone has any other ideas for what I should check, please let me know!

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I’ve done a lot more diagnostics on this unit since my last post. I have corrected all of the issues the unit had except for one. The loudspeaker will not activate. It just pops at the same volume when the button is pressed without going through its three levels of amplification. This is with two new batteries installed. Is anyone here familiar with the specific issue on the Harris TS22A?

Thanks in advance!
-Garbleduser

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Does anyone have circuit schematics for the Harris TS22A?

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Unfortunately service information and schematics for much of the equipment in this industry is a closely guarded secret. Why? I don't know, especially for something like this that was discontinued many years ago.

If the information was in demand somebody would have reverse engineered it, but, sorry to say the TS22 isn't in that category.

-Hal


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Thank you so much for your reply! I’ve been removing most of the conformal coating from this unit. I’m hoping to get some good pictures to assist in making a complete parts list for the main board. eventually I’ll do the secondary board, which fortunately has very little conformal coating. Some of the components have been a pain in the keister to identify. It was quite time intensive To identify the PTC resettable fuse located under the 9 V battery holder.

If anyone would be willing to compare component values of items on the main board, I think we could find out a lot. The yellow capacitor located at C1 for example has markings on it that don’t seem to correlate with anything I search for. In terms of all the daughterboards on the secondary board in the earpiece capsule, does anyone here have any information on what the individual boards do? I would love to compare pictures to help identify what is on the sanded off chip! In terms of the daughterboards, what I really want to identify is what controls the speakerphone.

As I said in a previous post, the only thing that happens when the speakerphone button is pressed is a pop, each time at the same volume. When the device was in perfect condition, the speaker would amplify three different levels of dialtone or hum when pressed. (Now it just sounds depressed…) If someone has any idea what the cause of this could be, please let me know. Please assist me in tracking this issue down, so we can provide good information to anyone else in the community that our discoveries may help!

Thanks in advance!
-Garbleduser

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Dont know if this would work but if you had another buttset you could clip on to the speaker leads and see what you get. Might eliminate the speaker as part of the equation.

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The speaker shows the correct impedance. Unfortunately the actual speaker mechanism is not the issue. I wouldn’t be surprised if there is a low power voltage regulator chip that Has succumb to age. More exploratory surgery is required.

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UPDATE!

I have been working on this issue for a few years on and off. In my latest attempt, I identified a low power audio amplifier chip that may be the issue. The IC is on one of the daughterboards in the earpiece capsule. The OEM part is a Motorola MC34119. I will be testing replacement parts when I am free in a few weeks. I will try both OEM and other (more available) versions of the IC. If replacement of this chip doesn't remedy the issue, be assured that I will continue to search for the actual solution, and will not stop until it is resolved.

I hope this works, wish me luck!
-Garbleduser

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Good luck!


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More news.
I have found that the amplifier chip is not the issue. I have tried 3 different versions of the same chip, all compatible with the original, and there was no correction or alteration of the failure. For my next attempt, I will be replacing the "latch" IC, which is actually a 74HC4520 binary counter chip.

I will get this figured out and share the correct fix, so places who won't share their fix, can go *long and descriptive expletive deleted.*

Is it within the rules to point out companies who act like this? I would love to, but I don't want to get in trouble here! Let me know if it's ok, and I will drop their name. I will share that they have a youtube channel with comments disabled.

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We probably don't want to flame other companies on here, but I hear your frustration! You ultimate solution will be much appreciated on the public record aok


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Correction:
The IC is an HC4051A. I got confused between datasheets. It is an analog multiplexer/demultiplexer chip. There are 2 of them on the daughter board that controls the speakerphone.

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