ongoing Howtek 4500 issues

[Tyler Boley]

I have some consistent behavior to report now. It seems anything that initiates drum rotation results in the same problem. The drum moves over from rest position about 6" and begins spinning. It then spins for about a minute, and stops.
If it was initiated with silverfast, say for a prescan, it exhibits this behavior during "check lumens", then reports a 702 error on the scanner then stops, and Silverfast reports "cannot focus". I doubt that's the problem, I just think the software is waiting for the scanner to complete calibration and focus to move on. If I hit OK in the alert, it resets the scanner to "ready" and I can start another prescan, same result.
With the FST diagnostic, it does fine with the initial tests that do not initiate spin. But the rest, the same things happen- drum scoots over about 6" and then spins for about a minute. The difference with the FST is that when the rotation stops, it immediately starts again, for another minute, and we're stuck in this cycle. Not a loop test, but a one time test.
Any suggestions at all would be helpful, I'm very close to calling time of death.
Thanks, Tyler

previous troubleshooting and activity are here-
http://www.largeformatphotography.in...canners/page22
and here-
http://www.largeformatphotography.in...ek-4500-issues
-however I think the above behavior is symptomatic of the main problem, yet undetermined

[mcfactor]

Not sure if this will be helpful. But, I have been having issues with a d4000 where while it is running through its checks, the scanner resets itself (according to the readout on the scanner), but the drum keeps spinning and silverfast freezes. I have found that if it do a soft reboot on the scanner (press the 3 buttons at the same time), but dont touch silverfast, the scanner will stop, then restart itself and continue to scan normally. Good luck.

-Noah

[Tyler Boley]

I'll try anything, thanks for your suggestion, unfortunately did not work here.

[ethanfg]

Tyler,

I think it would help if you either recorded a video, or wrote down the sequence of messages that are shown on the scanner screen during the prescan calibration. This way we can see at exactly what point it fails.

Ethan

[Tyler Boley]

sorry for the delay, I appreciate your interest. I was waiting for a new scsi cable to arrive to eliminate that from the variables, seemed to get lost in transit for about 3 weeks...
Here is the sequence-

scanner display-
READY TO SCAN
SCSI(4) R813

initiate prescan in Silverfast, scanner starts spinning, drum moving to position, lamp on
scanner display-
CALIBRATING...
BIAS & GAIN 17

for 10 seconds then that little mouse sound, still spinning and display changes to-

CALIBRATING...
CHECK LUMEN

this display, and spin, continues for 30 seconds, then-

CALIBRATING...
ERROR F702

and spin down, drum reposition, inactive with above display for 25 seconds, then-

scanner display shows Scanner Softboot for about a second, with normal attendant sound softboot, and back to

READY TO SCAN
SCSI(4) R813

corresponding with that change Silverfast shows the error it can not focus, with a button, when pushed scanner softboots again and both it and Silverfast are back to ready, the whole thing can be initiated again, with the same results.

I've been stuck here for months now, have tried a myriad of things all reported in these threads, it may be dead even if the solution is simple, I just can't find it. Crating, shipping, and service expenses unfortunately exceed being remotely justifiable.. this thing may be done, I sure am close. Thanks for any help

[datro]

I don't know if this will help (I know, it is really frustrating to keep hearing that ) but here is the full sequence my 4500 goes through when I start a Preview scan. NOTE: This is using DPL 8.1 software, not Silverfast, so it is quite possible there could be differences in the startup command stream to the scanner.

READY TO SCAN
SCSI (4) R813

--> Start the Preview in DPL 8.1

--> Drum starts spinning
CALIBRATING . . .
BIAS & GAIN 11

CALIBRATING . . .
CHECK LUMEN

CALIBRATING . . .
LINEAR S.H.V.

CALIBRATING . . .
LOG S.L.B.

CALIBRATING . . .
LOG S.G.

CALIBRATING . . .
LOG S.L.B.

CALIBRATING . . .
LOG S.G.O.

CALIBRATING . . .
LOG S.P.C.

CALIBRATING . . .
WHITE

CALIBRATING . . .
LOG S.P.C.

CALIBRATING . . .
LOG F.F.B.

CALIBRATING . . .
REFS & DELTAS

--> Drum bed moves to start position for the mounted negative

Scanning x%
< TO Stop

From hitting the "Preview" button in DPL 8.1 until the scan actually starts is about 18 seconds. Some of the above calibrating states go by VERY quickly. I captured the sequence by doing a video of the display panel and then playing it back manually to see each step. Otherwise I would not have actually been able to see some of them. Also, most of the steps above include a counter which typically starts at 0 then counts up to some number before moving to the next step. For example, the "LINEAR S.H.V." step counts from 0 - 11 before the next step occurs.

According to the Service Manual F702 is a "Collection WDT" event. I'm pretty sure "WDT" means WatchDog Timer. It just means that the calibration routine throws the F702 after a (watchdog) timer pops indicating that something did not succeed in the allowed time. But I don't have a clue what is meant by "Collection" in this case.

While it may seem that it is the CHECK LUMENS step failing on your 4500, I think it is also (slightly) possible that the collection of data for the NEXT step in the sequence might be the problem. It really depends on how the calibration routines are written.

"LINEAR S.H.V." is the step which comes after CHECK LUMENS on my 4500. My guess (based on a quick look at the "Handouts Training.PDF document") is this means "Search High Voltage" (S.H.V.) on the PMTs. The PMT power supplies (one for each of R,G,B) take 24V as input and output around 1.0KV to drive the PMT, so testing these supplies will probably require someone with the proper tools and expertise to work around these kind of voltages.

Also, have you changed any of the PMTs as part of your diagnostic work so far?

FWIW,
Dave

[Gary Beasley]

If its failing at the check lumens it there any chance of the light source going bad?

[Tyler Boley]

sorry the history of this attempted repair is long and in too many posts... I have about 1/2 dozen good bulbs I constantly switch out, I'm sure that's not the problems.. also, 702 errors tend to be speed errors, several things are going on before it'll go to the next step after check lumens