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Excellent concise manual. All needed information was included. Typeface and diagrams were clear. Very fair price considering what others are charging. Many thanks
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Response is a little slow- I had to wait 12 hours to receive download link but it says that it may take up to 24hrs.
Manual is old and was not produced in PDF- scanned copy is exellent.
Overall- value for money- I recommend
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Excellent quality and quickly delivered manuals at a fair price. Great care is taken in the reproduction process. Even photographs and highly detailed drawings are as clear as in the original. That cannot be said for some freelance manual copies I have obtained from the web. If you have exhausted your internet search of technical manuals, try Owner-Manuals.com. If they do not have it, I do not think it exists. Perhaps, if requested, they may be able to find it. Their resources are certainly greater than most. Shopping here certainly beats waiting for months or years for the manual you seek to appear in an internet auction or garage sale.
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Very detailed product, also it is a scanning from original, very useful if you have to service this type of amplifier ! Very good product, very hard to find!
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the Manual was made available as promised, the scans were excellent..Good Work !!!
Model 428B 5-59. TROUBLESHOOTING. 5-60. FRONT PANEL TROUBLESHOOTING. 5-61. The Front Panel Troubleshooting Tree was designed for use as a means to guide the repairman to a block of circuitry. This procedure, in combination with the adjustment, calibration, and performance checks should be adequate to repair most 428B's. 5-62. In any case where the front panel troubleshooting does not lead to the problem, it will be necessary to troubleshoot the instrument in detail. 5-63. DETAILED TROUBLESHOOTING. 5-64. Probe Check. 5-65. Resistance between pins 1-3, 1-4, 2-3, and 2-4 of the probe cable connector should be nearly identical and in the area of approximately 4 1/2 to 5 ohms. Where a resistance measurement between any of the above pairs of pins is significantly higher than between the other pairs (by about 3 times), an open probe coil is indicated. Any open circuit indicates a broken conductor between the plug and the bridge. The broken conductor is probably a broken wire in the cable. Either condition could indicate a broken wire at the Probe Terminal Section (see wiring diagram, Figure 6-1). 5-66. Power Supply Check. 5-67. To test the power supply: a. Measure +272 ±6 Vdc between Test Point 5 and ground. b. Measure +12 ±1 Vdc between the cathode of CR10 and ground. c. Measure -7 ±1 Vdc between the anode of CR9 and ground. 5-68. Where the +272 V and the +12 V have both failed, check the +12 first. Check CR10, Q1, C66, and C69.
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