MSF 5000 - Help with Non Functioning SSCB Issue

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ve3ei
Posts: 5
Joined: Thu Sep 06, 2001 4:00 pm

MSF 5000 - Help with Non Functioning SSCB Issue

Post by ve3ei »

I have a UHF MSF5000 with SSCB Board TLN3043N 4306P and SSCB Personality Module 5191012C27 cs=0C50 which is non-functioning.
The station had been functioning properly and then just quit. It may have been a lightning strike but there is no other evidence of same. I have tested the voltage outputs using the troubluleshooting procedure and they are fine. I have replaced the personality chip with another and the syptoms as described below are the same.
The symptoms I have are as follows:
1. On Powerup the SSCB module LED goes to 888 with no operation and no indication on the DMP
2. Pressing the "Reset" once it goes to "Rx Lock" and the squelch opens, but I do not know on what frequency.
3. Pressing the "Reset" once more turns on PA Full, PA on, RX lock, PA key and the unit transmits with full power on approximately 430.450 MHz.
4. Pressing "reset" once more and the station goes back to step 1
It periodally steps through the same process. The LED display never changes from 888

Any ideas? Anyone seen this before?

Eric Meth ve3ei
Eric Meth ve3ei
sledude
Posts: 59
Joined: Sat Oct 07, 2006 6:35 pm
What radios do you own?: QuantarV&U,ASpec,XTL,XTS

Post by sledude »

Eric, maybe you should go ask Duane for another SSCB.
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kcbooboo
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Post by kcbooboo »

It almost seems like the reset signal, generated when you release the reset switch, isn't working properly, so the microprocessor isn't doing its thing. Could also be a crystal or oscillator problem.

Swap whatever you can. I think the microprocessor and ASIC chips on the SSCB and TTRC are identical, so that's worth a shot.

Otherwise it's most likely FUBAR.

Bob M.
kgb
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Joined: Sat May 07, 2005 11:13 pm

Post by kgb »

Eric,

Make sure your primary supply voltage (feeding the station from its own power supply or another external source) is north of 12V or 12V at absolute minimum. The DC-to-DC converter can get unstable and not provide reliable 5V to the SSCB's digital core. Other funny things happen also. Naturally, this also affects the CPU's oscillator.

Often when on the ragged edge, the reset switch (which goes to the DC-to-DC converter and not the 68HC11 itself) can "kickstart" things. Depending on where your voltage is, it can work for a while or fall on its face quickly. Sounds like the latter in your case.

Bob is correct - the SSCB CPU and ASICs are identical to the TTRC core's compliment of same. Any old 68HC11 won't work; those in SSCBs and TTRCs have a small bootstrap program that set them up for the external EPROM(s). Always be sure to use a proper PLCC extraction tool, even the $10 special from Radio Shack. It's *very* easy to split a socket otherwise. Take care in extraction and insertion always.

Good luck!

-The Gronk
Lake Effect
Posts: 311
Joined: Tue Dec 06, 2005 9:47 am

Post by Lake Effect »

Possibly a bad filter cap on the A+ input. A 660mf cap (C709 I believe). They have caused strange things to happen with these stations in the past.

L.E.
kgb
Posts: 23
Joined: Sat May 07, 2005 11:13 pm

Post by kgb »

Yep, LE is right on that. Electrolytics and MSFs have a bad marriage history. CLBs moreso than CXBs (famous no-name cap problem on CLB control board) but they're always a possibility.

-The Gronk
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