Harley Benton GA 15 Скачать руководство пользователя страница 25 | Manualshive

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Harley Benton GA 15 Скачать руководство пользователя страница 25

- Cosmic Ampworks

®

- The Ultimate Harley Benton GA15 Mod Kit- Version 1.4 - 200127

© 2020 -

www.cosmicampworks.com

25 Dedicated to the Advancement of Stellar Tone!

Figure 30. Cut the circuit board traces that conduct electricity to the power tube heaters (cuts encircled). Then drill three holes for the
new heater supply wiring (6.3 V spade connectors marked with orange rectangles). Tube heaters are connected to tube pins 4 and 5.

Figure 31. Drill three holes (1-3) for the new heater supply wires. Then twist two lengths of single stranded wire. Connect pins no. 4 of
both output tubes to each other and so the same for pins no 5. If using wires of identical color, use a marker to distinguish them.

Hole 1

Hole 2

Hole 3

Power tube

Power tube

Hole 2

Hole 1

Cut 1

Cut 2

Hole 3

Screw hole

4

5

4

5

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Содержание GA 15

Страница 1: ...n risk and should only be done by properly trained personnel The modifications described in this manual do not necessarily comply with any electronic safety standards Disclaimer Cosmic Ampworks assume...

Страница 2: ...etting distorted Less gain results in a somewhat more jangly tone The most challenging mods some of which are optional 5 Assembling and installing a James tonestack and volume control on the back of t...

Страница 3: ...these are the most dangerous ones But you can t easily see what parts are connected to which filter caps so maintaining the highest level of caution AT ALL TIMES is required There is only one way to...

Страница 4: ...d vice versa Then use one hand to check for remaining high voltages with the red probe Figure 3 If your multimeter does not have a clip on ground probe a less advisable alternative is to hang the nega...

Страница 5: ...and With that hand hold the red multimeter probe carefully against the resistor s legs and check the voltages Not measuring any remaining voltages at F3 or R38 shortly after switching off the amp is a...

Страница 6: ...heatsink 3 2 Additional requirements Apart from the items included in this mod kit the following things are required for successfully implementing the Ultimate GA15 mod 1 Safety goggles 2 Soldering i...

Страница 7: ...e chassis from the cabinet by slightly lifting and sliding it backwards 6 Carefully check for any remaining high voltages stored in the filter caps using a multimeter as described above p 3 5 and keep...

Страница 8: ...inside the red fields Figure 7 need to be removed From experience leaving them in place may affect sound quality and even result in fuzz like background sounds So take note of each component s number...

Страница 9: ...are to be removed for the Ultimate Mod are in the red fields NOTE 1 If you re not so confident in your soldering and electronics skills yet it may be best to start with removing only the parts that a...

Страница 10: ...are to be installed in place of R2 and R6 setting the bias of the first preamp tube to a more normal value than the stock GA15 which is biased very cold For now ignore Wires 1 2 and 3 these connect to...

Страница 11: ...On one end remove a couple of millimeters of insulation from both strands and them into the two holes of R5 Figure 9 Wire 2 and Wire 3 On the other end of the wire solder strand that runs from the re...

Страница 12: ...en that applies to the situation where the shaft is facing the user and the lugs are on top as in Figure 11 Figure 12 Mount a local feedback 1M feedback resistor underneath the board by soldering one...

Страница 13: ...180k R3 10k iii C1 330p C2 470p C3 4 7n C4 3 3n b Cut two lengths of single stranded wire of some 7cm each Connect one side of the one wire to the junction of R3 and C4 and one side of the other wire...

Страница 14: ...to center lug of the volume pot Figure 15 Tonestack and volume control assembly d Connect volume control and tonestack assembly to the circuit board i Cut a length of about 15 cm of speaker wire sepa...

Страница 15: ...al presence control and modified phase inverter see further down Figure 17 The tonestack the left two potmeters and volume control right pot assembly has 3 connection points to the circuit board SIGNA...

Страница 16: ...e that connects holes 2 and 5 should be about 1 5 cm Figure 20 After drilling smoothen the edges of hole 1 with some sanding paper and or a file and remove any burrs d Clip three lengths of speaker wi...

Страница 17: ...derneath the board not clipped component legs Make sure not to heat the L7912 s legs for too long or the sensitive component may be damaged h Drill two holes best from the underside of the board near...

Страница 18: ...eatsink locations indicated with white circles for attaching it to the chassis with two tie wraps Don t worry about the heat because the heatsink has such a large capacity that its temperature will no...

Страница 19: ...ircuit board traces the trace near hole 2 can be interrupted when drilling the hole because the heater traces spread hum throughout the circuit in their stock layout Figure 22 Drill two holes near the...

Страница 20: ...it runs a couple of centimeters above the board and then lead it through hole 3 then solder it to the tube socket connection of pins 4 and 5 V2 Figure 23 l Lastly close the DC heater circuit by conne...

Страница 21: ...mm of insulation from the ends Solder the end that runs from the rear hole of J12 to the left lug of the 5k potmeter Figure 26 Solder the other strand to the right lug Solder the legs of the 0 1uF cap...

Страница 22: ...J12 to the left lug of the 5k potmeter Solder the other strand to the right lug Solder the legs of the 0 1uF capacitor to the right and center wiper lugs of the 5k potmeter Solder one leg of the 120k...

Страница 23: ...r the wire to the trace on underside of the board which also holds spade connector T14 Figure 28 Interrupt the PCB traces on either side of the front leg of C15 Figure 14 Cut a length of single strand...

Страница 24: ...s cancels out a First cut the two circuit board traces that conduct 6 3 V AC to the power tube heaters Figure 30 with a Dremel tool with grinding attachment with a rotary drill or with a simple file b...

Страница 25: ...he new heater supply wiring 6 3 V spade connectors marked with orange rectangles Tube heaters are connected to tube pins 4 and 5 Figure 31 Drill three holes 1 3 for the new heater supply wires Then tw...

Страница 26: ...orks com 26 Dedicated to the Advancement of Stellar Tone Figure 32 A last look at the circuit board and that s a wrap Hopefully modifying your amp has yielded satisfactory results and some agreeable h...

Страница 27: ...smic Ampworks The Ultimate Harley Benton GA15 Mod Kit Version 1 4 200127 2020 www cosmicampworks com 27 Dedicated to the Advancement of Stellar Tone Figure 33 Schematic of the modified Harley Benton G...

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