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Technical Bulletin TRM/95

There are several variables that can cause short developer life in the Model 1124 Viking™ plate processor. Short developer life will show up as undeveloped plate back- ground when the plate comes out of the processor or as sensitivity on roll-up on press.

Tech Service offers the following recommendations to correct short developer life.

Developer Change and Replenishment
Before handling or using any chemical, be sure to read the Material Safety Data Sheet for health hazard data, precautionary information and suggested first aid.

Change the developer every 30 days or 500 square feet of plate material processed per gallon of developer, whichever comes first. Model 1124 processor holds 2 1/2 gallons of developer and will develop up to 1250 square feet of plate material per developer change. Use Viking™make-up solution to replenish the developer.

Make sure the proper procedure is being followed to change developer. Tech Service has found customers using Viking™make-up solution for developer. Viking™ make-up solution is only 1/2 the strength of Viking™ 2-in-1 developer-gum.

Developer Temperature
Make sure the temperature of the developer coming out of the spray tubes is at 82 degrees F ± 2 degrees. Low temperature will cause poor cleanout and high temperature will cause the processor to replenish at a higher rate causing the developer to deplete faster than normal.

Filters
Use only the recommended filters for the processor.
*DO NOT use film filters.
*Watch for plugged filters which will restrict the flow of the developer causing poor cleanout of the exposed plate.
*DO NOT use a filter with a metal core. The core of the filter must be plastic. A filter with a metal core will cause the desensitizing salts in the developer to be neutralized. This in turn will cause poor cleanout of the printing plate.

The following filters are recommended for the Model 1124 processor. When ordering one of these filters from a Graphics Arts dealer, do not accept a substitute filter.
Mansville - C 3.5 EP
Filterite - C10 A10U
AMF Cuno - DCCPC

Brush Pressure
Check the brush pressure and adjust it according to the Flat Brush Pressure Adjustment procedure. If necessary, also perform the Rear Pull Test Procedure.

If the brush has been set at a high brush pressure, it may need replacing. DO NOT PUT BRUSHES UNDER MORE PRESSURE THAN IS RECOMMENDED. The brushes will take a set at high brush pressure which ultimately will cause less pressure.

Flat Brush Pressure Adjustment
Proper adjustment of flat brush pressure for Viking™plate processors is necessary for optimum Viking plate cleanout. Correct adjustment provides even pressure along the length of the flat brushes. Use the spring scale method described below (Setting Flat Brush Pressure) to ensure proper adjustment.

Never over-pressure the flat brushes. Too much pressure will cause the brushes to "take a set" and they usually will not recover and will have to be replaced.

NOTE:
*When brushes are new, perform the following:
­ Check pressure daily for the first week and monthly thereafter.

*Rotate brushes 180° every 90 days and reset pressure for maximum brush life.

Setting Flat Brush Pressure

Required Tools
*Hex wrench, 9/16 inches
*Spring scale, 0-2000 grams
(P/N 78-8028-8534-9)
*Hole-punched test strip 3 1/2" x 9 1/4" (see figure in Step 9).

Procedure

1. Turn the POWER switch off.

WARNING! DO NOT PERFORM THIS PROCEDURE WITHOUT DISCONNECTING PROCESSOR FROM MAIN POWER SOURCE UNLESS INSTRUCTED TO DO SO. IF POWER IS NOT DISCON- NECTED, YOU MAY BE EXPOSED TO LIVE COMPONENTS OR MOVING PARTS.

2. Remove the top cover and developer sump cover.

3. Loosen the locking capscrews and the flat brush adjusters.

4. Tighten adjusters until the top and bottom brushes make contact with each other.

5. Turn ON the processor. If the processor is a new installation or has not been in operation for 8 hours or more, soak the flat brushes for about 15 minutes. After 7 minutes, process a plate or plates as wide as the flat brushes. If the processor has currently been in operation, soak for 2 minutes and process a plate or plates as wide as the flat brushes.

6. Turn OFF the processor with the brush ends aligned.

7. Inset test strip between the flat brushes, at the center adjuster, with the hole-punched edge toward the front of the processor, up to the nip of the second set of transport rollers.

8. Pull back on the test strip until the brush bristles are aimed outward from the processor.

9. Attach the spring scale to the test strip.

10. Pull back on the test strip and measure the brush pressure.

11. Tighten or loosen the adjuster to obtain the following brush pressure.

S2 5 or 6 mil test strip
1100 grams ± 100

G1/G2 8 mil test strip
1200 grams ± 100

G1/G2 12 mil test strip
1300 grams ± 100

NOTE: After the pressure of the flat brushes has been adjusted, this same pressure is used when processing plates of any caliper.

12. Repeat at all adjacent adjusters.

13. Recheck all adjusters.

14. Tighten all capscrews.

NOTE: Further adjustment may be necessary if the plate does not clean out properly. (See Flat Brush Condition.)

Flat Brush Condition
If you are having problems with plate cleanout or short developer life, check the condition of the flat brushes. Use the following procedure.

1. Take a spring scale reading, pulling the test strip toward the front of the processor, using the Setting Flat Brush Pressure procedure.

2. If necessary, adjust pressure as recommended in Step 11 of the Setting Flat Brush Pressure procedure.

3. When you get a correct readout, take a spring scale reading pulling the test strip toward the rear of the processor (use the Rear Pull Test Procedure below).

Rear Pull Test Procedure
1. Remove the second set of transport rollers:
A. Remove left guard.
B. Lift rollers up and out of the processor.

2. Insert test strip between flat brushes from rear of processor, under center adjuster, with the hole-punched edge toward the rear of the processor.

3. Attach the spring scale to the test strip. Position the scale to 0.

4. Gently pull the test strip toward the rear of the processor.

Record the spring scale reading.

5. Repeat for all adjusters.

6. The difference between the readings of the front pull and rear pull should not be more than 300 grams.

Example:
Front pull 1300 grams

Back pull 900 grams

1300 grams

- 900 grams

400 grams

If the difference between the front and rear pull is 300 or more grams, replace the brushes.

7. Replace the left guard.

8. Replace the top covers.

Copyright 1996 Imation. All rights reserved.