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Thread: Tektronix 4052 Troubleshooting

  1. #11

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    Quote Originally Posted by nikola-wan View Post
    Thanks for a great diagnostic board - Jos!!

    Monty
    You're welcome, but it is Tektronix that did the hard work. I just moved the design from 1975 to 1985......

    I still have more than 10 left ! First come , first served !

    Jos

  2. #12

    Default My 4052 text issue is now fixed

    I couldn't wait for delivery of the 7405 inverter - so I went to the Houston EPO Surplus Outlet and picked up a couple of 7405 - and several NOS old capacitors that I may need to fix my 4054.
    In fact I did some more 4054 power supply tests and it appeared the output 5V cap (250uF 20V) was not working.

    This morning I carefully unsoldered the bad 7405 and cleaned flux off the board and soldered in the new one.
    I ohmed the "A" inverter section and the other two I could see traces for - and all three connected up to the traces.

    I put the board assembly back together - bolted into the chassis, powered it on - and I had text and graphics!

    IMG_6747.jpg

    I then did some calibration on text and cursor intensity before putting the cover back on.

    Monty

  3. #13

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    Hi all,

    just to let you know I finished my DRP and it was up and running straight away -- thanks, Jos!

    My 4052 passed the short and long RAM, as well as the ALU tests. The CRC test (see below) agrees with the published checksums for the v5.1 firmware (on a rev9 MAS in my case), but the U805A/B and U897A/B results leave me puzzled.

    DSCN0723.jpg

    According the checksum documentation, these are "valid extensions" of U820 and U870 for the v5.1 firmware and for the 4052A, because there IS no U805 and U897 installed. In these cases, the following correspondence holds:
    • U805A --> U820C
    • U805B --> U820D
    • U897A --> U870C
    • U897B --> U870D

    Can anyone make sense of this? What exactly does U820C/D and U870C/D mean, considering those chips have already checked out OK a few lines above in the DRP output?

    I'll have to check if my rev9 MAS does infact omit the patch ROMs U805 and U897 to verify this output. I'll have to dig thru my previous photos, but failing that, I might have to actually pull the entire board assembly again.

    Best regards,

    --Roland
    "END OF LINE" [MCP, 1982]
    "An admin that isn't a bit hackerish is just the guy mopping up the keyboard" [Phrack V0b I3f P12]
    "Any appearance of danger is simply a device to enhance your experience" [Futureworld, 1976]

  4. #14

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    Quote Originally Posted by GanjaTron View Post
    Hi all,

    Can anyone make sense of this? What exactly does U820C/D and U870C/D mean, considering those chips have already checked out OK a few lines above in the DRP output?

    --Roland
    Roland,

    That is puzzling. I read the notes after the CRC list and it is still not clear why they would report those - unless the 820 and 870 ROMs actually contain multiple smaller images - each with a checksum.

    I found the ROM images I captured with my Data I/O and notes I took after purchasing my 4052 in 2000 - but apparently I upgraded my ROMs since then as those images are v4.1 and now I have v5.1.

    Monty

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