MTR2000 no TX repeat audio

[VE3TUH]

Hello Guys. I have several MTR2000's, vhf, in hamster service. They have proven to be a pretty reliable machine and I really like them. I just had one fail with no repeated tx audio. The problem appears to be the control board, swapped it out, retuned and all is good. I would like to try to fix this controller, anybody have any experience with this failure, if its a common issue I could use a hint as to where to start looking. Thanks!

[d119]

Since there is little to no public documentation or schematics on this particular stuff, good luck... And I don't mean to come off as a jerk. These are some of the hardest stations to work on due to the lack of publicly accessible documentation.

[VE3TUH]

The schematics are in the service manual. I have the manual, but it will not be an easy task to repair, its a pretty complicated unit. Which is why I was wondering if anybody else has any experience with it. I did some testing and found that the local mic audio is also muted, which should help to isolate the fault a bit.

[Bill_G]

Really? You have schematics?

[gtriever]

Really? You have schematics?

<echo> Yeah, really?

[VE3TUH]

The disbelief is almost insulting.

Service Manual, complete with schematics 68P81096E40-O
Instruction Manual 68P81096E30-A

[Bill_G]

Sorry. The incredulity is because I've attempted to obtain a full service manual for the MTR2K, MOT refused to fulfill the order.

[VE3TUH]

I dont know. I didnt realize what a gem I apparently have here. It is how I figured out how to trick the 100 watt pa into thinking it was a 40 watt, getting full freq range, but lower power out of it. guess I'll dive into the controller when I have time, cant do any harm, and possibly fix the tx audio issue. I wonder if you tried to obtain the 2 part numbers mentioned above?

[Bill_G]

Well, it has been years. As these things fall into the legacy support category, it would probably be wise to get a manual. Thanks for the part numbers.

[gtriever]

I'll echo Bill again. I didn't know such an animal actually existed (MTR manual w/ schematics). Thanks for the part numbers!

[kb8poo]

Had this same "no TX repeat Audio" problem before but was able to fix with station alignment. Read code plug and looked at TX DBM level which was
set to zero DBM for 4-wire wireline config. Increased the TX DBM by 2 and wrote codeplug back to station, TX repeat audio working now but audio level was too high, over deviation. Changed TX audio back to the original zero DMB and TX repeat audio was working normal again.

Not sure what really caused the problem, seems like it was more of a software issue than a hardware problem.

[VE3TUH]

Thanks, I never thought to try a codeplug rewrite. I'll give it a shot.

[wavetar]

Well, it has been years. As these things fall into the legacy support category, it would probably be wise to get a manual. Thanks for the part numbers.

They don't show up on MOL. The manuals and part numbers have always existed, but not available to dealers or the general public. Limited to internal M depots and probably Fed repair facilities. Why let a dealer do a $50 repair when you can force them to buy a $2500 FRU, amiright?

[Bill_G]

Well, it has been years. As these things fall into the legacy support category, it would probably be wise to get a manual. Thanks for the part numbers.

They don't show up on MOL. The manuals and part numbers have always existed, but not available to dealers or the general public. Limited to internal M depots and probably Fed repair facilities. Why let a dealer do a $50 repair when you can force them to buy a $2500 FRU, amiright?

Well, unlike the old days when customers would hang on to Motracs for 20 years, have five different versions of them, plus some Mastr Pro's, a couple Johnsons, maybe a Midland, a Uniden, and a handful of Wilson/Regencys, when people swap out their MTR2k's, we never see it again. I can only think of two customers with MTR2K. Everyone else has upgraded to MTR3K, GTR, or Tait TB8x and TB9x base stations. So, the manual shelf is slowly emptying out.

[VE3TUH]

Thanks kb8poo. The station alignment worked. Never thought to try that, as it was inservice and working when it failed, but doing the procedure on it restored the tx audio.

Randy