Maxtrac quandry

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MP 6.7
Posts: 109
Joined: Mon Aug 22, 2005 11:00 am
What radios do you own?: Spectra, Maxtracs, MT2k, GP300

Maxtrac quandry

Post by MP 6.7 »

I just picked up a VHF Maxtrac (D43MJA7DA5CK, SN 428FPJxxxx, 9313A logic and 4322B RF) that is doing something I've never seen in a Maxtrac before. The codeplug that came with it has two modes. I went in to reprogram it with 11 modes in the 160MHz range RX only with RSS R06.01.00. After programming, I power cycled the radio and it beeped like normal, made a low boop for 5 seconds and then functioned normally. It didn't do this with the original codeplug. I did a little experimentation and found that no matter what I did to the codeplug, if I left mode 1 the same frequency as it was in the original codeplug it wouldn't do the boop on power up.

This is a pretty simple codeplug with 16 channel capability and no signalling, so there aren't too many places to screw up...hence the fact that I'm stumped!
Dale
KE7CEU
Current radios
Mobiles: 3x D43 A7 Spectras, T83 A9 Spectra, 2x KLM and 2x KLN MCS2000's, D43 Maxtrac 32ch, D35 Maxtrac 6ch modded for 896MHz receive, M33 M1225 4ch, Lowband Maratrac on 6 meters
Portables: 2x VHF GP300, VHF P110, UHF P110, VHF A7 MT2000
Will
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Re: Maxtrac quandry

Post by Will »

Emergency Jumper missing.
MP 6.7
Posts: 109
Joined: Mon Aug 22, 2005 11:00 am
What radios do you own?: Spectra, Maxtracs, MT2k, GP300

Re: Maxtrac quandry

Post by MP 6.7 »

It's there...that was my first thought, however I tried using a known good 16 pin plug with the jumper in place and same result. Still doesn't account for why changing mode 1 makes it start doing it.
Dale
KE7CEU
Current radios
Mobiles: 3x D43 A7 Spectras, T83 A9 Spectra, 2x KLM and 2x KLN MCS2000's, D43 Maxtrac 32ch, D35 Maxtrac 6ch modded for 896MHz receive, M33 M1225 4ch, Lowband Maratrac on 6 meters
Portables: 2x VHF GP300, VHF P110, UHF P110, VHF A7 MT2000
Al
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Re: Maxtrac quandry

Post by Al »

Try reprogramming the tuning codeplug. The only other possibility is a bad logic board.
MP 6.7
Posts: 109
Joined: Mon Aug 22, 2005 11:00 am
What radios do you own?: Spectra, Maxtracs, MT2k, GP300

Re: Maxtrac quandry

Post by MP 6.7 »

Yesterday I blanked and re-initialized the radio and it still does it...looks like there might be a hardware problem. It's going into data receiver duty anyway so it really won't matter if it sits there and boops for five seconds on power up because the speaker will be disconnected. The flat audio output is active as soon as the radio is powered up.
Dale
KE7CEU
Current radios
Mobiles: 3x D43 A7 Spectras, T83 A9 Spectra, 2x KLM and 2x KLN MCS2000's, D43 Maxtrac 32ch, D35 Maxtrac 6ch modded for 896MHz receive, M33 M1225 4ch, Lowband Maratrac on 6 meters
Portables: 2x VHF GP300, VHF P110, UHF P110, VHF A7 MT2000
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xmo
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Re: Maxtrac quandry

Post by xmo »

A fault in the display control head will cause the Maxtrac to give the error tone at power-up. Try a different head.
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kcbooboo
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Re: Maxtrac quandry

Post by kcbooboo »

A low-pitched tone for 5 seconds at turn-on means the code plug has a problem, usually a bad checksum. The cures are to reprogram the radio, which you've already done, or replace the logic board.

The older logic boards used a Dallas DS1220 battery backed-up RAM chip for code plug storage. Newer logic boards use a parallel EEPROM such as a 28C16. If this particular radio has a Dallas chip for code plug storage the battery only lasts so long, and that could be the problem. However, depending on how many modes you've got programmed in (I think you said 2), the memory in the Dallas chip might not be used. If RSS writes out only 64 code plug blocks, then the entire code plug is being stored in the CPU's EEPROM. If it writes out 320 code plug blocks, then some of the code plug is sitting in the external (Dallas) memory.

New Dallas chips are still available but that will just delay the same problem for another 10 years. Replacing the Dallas chip with a real EEPROM solves the problem forever.

Bob M.
MP 6.7
Posts: 109
Joined: Mon Aug 22, 2005 11:00 am
What radios do you own?: Spectra, Maxtracs, MT2k, GP300

Re: Maxtrac quandry

Post by MP 6.7 »

I haven't tried another head...I'll give that a try.

It is an older logic board with the Dallas chip, so that does make sense. RSS writes 320 blocks no matter how few modes I program.

Is it as simple as dropping in a 28C16 and doing a blank then board replacement procedure again?
Dale
KE7CEU
Current radios
Mobiles: 3x D43 A7 Spectras, T83 A9 Spectra, 2x KLM and 2x KLN MCS2000's, D43 Maxtrac 32ch, D35 Maxtrac 6ch modded for 896MHz receive, M33 M1225 4ch, Lowband Maratrac on 6 meters
Portables: 2x VHF GP300, VHF P110, UHF P110, VHF A7 MT2000
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kcbooboo
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Re: Maxtrac quandry

Post by kcbooboo »

It should just be a matter of removing the Dallas chip and installing a 28C16 120ns chip. Mouser has them for about $10.50 each. I'd recommend installing a socket, not that you'll ever have to replace the chip again; it just looks neater.

You could also try blanking and initializing the radio for a model number with fewer than 16 channels and perhaps less features. That might put the code plug entirely into the CPU and it wouldn't need to use the external code plug space. As long as RSS only writes out 64 code plug blocks, all of that goes into the CPU. Once it switches to 320 blocks, things go into the external IC.

Bob M.
MP 6.7
Posts: 109
Joined: Mon Aug 22, 2005 11:00 am
What radios do you own?: Spectra, Maxtracs, MT2k, GP300

Re: Maxtrac quandry

Post by MP 6.7 »

Did a bit more experimentation today. A different head didn't change anything, but blanking and initializing with a 64 block codeplug fixed it. However I don't think there are any 64 block codeplugs that support changing the channel number from the sequential 1, 2, 3 etc.

Another Maxtrac I have has a 200ns 28C16 in it; is it OK to use something slower than 120ns (like 150ns) to replace the Dallas chip?
Dale
KE7CEU
Current radios
Mobiles: 3x D43 A7 Spectras, T83 A9 Spectra, 2x KLM and 2x KLN MCS2000's, D43 Maxtrac 32ch, D35 Maxtrac 6ch modded for 896MHz receive, M33 M1225 4ch, Lowband Maratrac on 6 meters
Portables: 2x VHF GP300, VHF P110, UHF P110, VHF A7 MT2000
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kcbooboo
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Re: Maxtrac quandry

Post by kcbooboo »

By only writing 64 code plug blocks, you've avoided writing to the external EEPROM/Dallas chip. That pretty much confirms that it's bad. Also, the date code on the chip (if there is one) will most likely indicate it's well over 15 years old.

I have only ever seen 120ns chips in my radios but my MaraTrac has a -200, so I guess it's OK. I haven't gone looking for those though; fleabay will probably be your cheapest source.

I don't know what one has to do to support mode naming (changing the usual sequential mode numbers). I've never tried changing them.

Bob M.
MP 6.7
Posts: 109
Joined: Mon Aug 22, 2005 11:00 am
What radios do you own?: Spectra, Maxtracs, MT2k, GP300

Re: Maxtrac quandry

Post by MP 6.7 »

Yeah that's what I figured. The Dallas chip has a date code of 8827 so it's way past its sell-by date. Ebay has a few 28C16-15's up right now for cheaper than Mouser so I'll probably give one of those a shot.

It seems like the 64 block codeplugs (Standard and MaxTrac product lines) don't support accessory plug programming, signalling and mode naming. The 320 block codeplugs (Max Options and Max High Sig product lines) allow typing in a two digit number for a mode name.
Dale
KE7CEU
Current radios
Mobiles: 3x D43 A7 Spectras, T83 A9 Spectra, 2x KLM and 2x KLN MCS2000's, D43 Maxtrac 32ch, D35 Maxtrac 6ch modded for 896MHz receive, M33 M1225 4ch, Lowband Maratrac on 6 meters
Portables: 2x VHF GP300, VHF P110, UHF P110, VHF A7 MT2000
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kcbooboo
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Re: Maxtrac quandry

Post by kcbooboo »

You're probably correct on your assessment of the capabilities of the various product lines. I've never tried to figure all of that out. I know the GM300 supports mode naming but I probably never had the right combination on a MaxTrac. I know how it's implemented in the code plug.

8827? I guess it's way past ANY date. 23 years for any battery is pretty darn good. I wonder when they switched to EEPROM.

Be careful of what you buy. I've seen some chips that have the same number but are PROMs or EPROMs. You want a parallel EEPROM, 24-pin DIP, sometimes called PDIP-24.

Bob M.
MP 6.7
Posts: 109
Joined: Mon Aug 22, 2005 11:00 am
What radios do you own?: Spectra, Maxtracs, MT2k, GP300

Re: Maxtrac quandry

Post by MP 6.7 »

Well I picked up some sockets and a 28C16 off Ebay making sure to get a through-hole chip (many on Ebay are surface mounts in the same package). Yanked the Dallas chip and dropped in the 28C16, then blanked and initialized. Works great now.

FYI, the 28C16 I got was a 150ns chip and it works.
Dale
KE7CEU
Current radios
Mobiles: 3x D43 A7 Spectras, T83 A9 Spectra, 2x KLM and 2x KLN MCS2000's, D43 Maxtrac 32ch, D35 Maxtrac 6ch modded for 896MHz receive, M33 M1225 4ch, Lowband Maratrac on 6 meters
Portables: 2x VHF GP300, VHF P110, UHF P110, VHF A7 MT2000
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