{"id":97958,"date":"2021-09-22T15:55:51","date_gmt":"2021-09-22T13:55:51","guid":{"rendered":"https:\/\/captain-guitar-lounge.com\/amp-modifications\/fender-pro-junior-modification\/"},"modified":"2023-05-17T12:44:26","modified_gmt":"2023-05-17T10:44:26","slug":"fender-pro-junior-modification","status":"publish","type":"page","link":"https:\/\/captain-guitar-lounge.com\/en\/amp-modifications\/fender-pro-junior-modification\/","title":{"rendered":"Fender Pro Junior Modification"},"content":{"rendered":"

[et_pb_section fb_built=”1″ fullwidth=”on” admin_label=”Startbild” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_fullwidth_image src=”https:\/\/captain-guitar-lounge.com\/wp-content\/uploads\/2021\/07\/IMG_0663-scaled-e1626448562304.jpg” title_text=”Pro Junior board” admin_label=”Vollbreites Bild – Amp von innen” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][\/et_pb_fullwidth_image][\/et_pb_section][et_pb_section fb_built=”1″ admin_label=”Mod_TopMenu1″ _builder_version=”4.14.7″ _module_preset=”default” background_color=”gcid-ccfbcf15-fa71-4d0d-98f3-88576b9bbe68″ custom_margin=”0px||0px||false|false” custom_padding=”0px||0px||false|false” sticky_position=”top” global_module=”41014″ global_colors_info=”{%22gcid-ccfbcf15-fa71-4d0d-98f3-88576b9bbe68%22:%91%22background_color%22%93}”][et_pb_row _builder_version=”4.16″ _module_preset=”default” custom_margin=”0px||0px||false|false” custom_padding=”5px||5px||false|false” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_menu menu_id=”1429″ active_link_color=”#FFFFFF” menu_icon_color=”#FFFFFF” _builder_version=”4.16″ _module_preset=”default” menu_font=”|700||on|||||” menu_text_color=”#FFFFFF” background_color=”RGBA(255,255,255,0)” global_colors_info=”{}”][\/et_pb_menu][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ admin_label=”\u00dcberschrift und Einleitung” _builder_version=”4.16″ _module_preset=”default” width=”100%” module_alignment=”center” custom_padding=”20px||20px||true|false” global_colors_info=”{}”][et_pb_row column_structure=”1_4,1_4,1_4,1_4″ use_custom_gutter=”on” module_id=”Top” _builder_version=”4.16″ _module_preset=”default” module_alignment=”center” custom_margin=”||||false|false” custom_padding=”0px||0px||false|false” global_colors_info=”{}”][et_pb_column type=”1_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”\u00dcberschrift und Einleitung” _builder_version=”4.16″ _module_preset=”default” module_alignment=”center” custom_margin=”||||false|false” global_colors_info=”{}”]<\/p>\n

Captain Amp Mods<\/strong><\/h3>\n

Fender Pro Junior<\/strong><\/h1>\n

The Fender Pro Jr. first hit the market in late 1993, or at least the first release was released in September 1993. Since then, much has changed. In almost 20 years of production the curcuit was altered somewhat.<\/p>\n

[\/et_pb_text][\/et_pb_column][et_pb_column type=”1_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”Versionen” _builder_version=”4.16″ _module_preset=”default” module_alignment=”center” custom_margin=”||||false|false” global_colors_info=”{}”]<\/p>\n

Versions<\/h5>\n

Versions such as Cream boards and Green boards are distinguished, as are the more obvious version changes in the name. Currently we are at version IV which are available in stores. On the used market you can still find all versions, which all differ in certain points – which one is the best, I am not able to say…<\/p>\n

[\/et_pb_text][\/et_pb_column][et_pb_column type=”1_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”Erfolgsrezept” _builder_version=”4.16″ _module_preset=”default” module_alignment=”center” custom_margin=”||||false|false” global_colors_info=”{}”]<\/p>\n

Key to success<\/h5>\n

The Pro Jr. is a success story: small, light, handy. Still decently loud for the (small) band or combo, pedal friendly and two knobs is more then enough. But…in almost twenty years some weaknesses have become apparent some of which have already been improved in newer versions even if not completely. Reason enough to help this little guy! Weak points are mainly the reliability and the sound variety, which is a bit meager, and the adjustment options are not particularly good, which has several reasons:<\/p>\n

[\/et_pb_text][\/et_pb_column][et_pb_column type=”1_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_image src=”https:\/\/captain-guitar-lounge.com\/wp-content\/uploads\/2021\/09\/ProJr.jpg” title_text=”ProJr” align=”right” _builder_version=”4.16″ _module_preset=”default” max_height=”400px” custom_margin=”15px||||false|false” global_colors_info=”{}”][\/et_pb_image][\/et_pb_column][\/et_pb_row][et_pb_row admin_label=”CSS Schwachstellen” module_id=”Schwachstellen” _builder_version=”4.16″ _module_preset=”default” custom_margin=”0px|auto|10px|auto|false|false” custom_padding=”12px||0px||false|false” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”\u00dcberschrift – Schwachstellen” _builder_version=”4.16″ _module_preset=”default” custom_margin=”||0px||false|false” global_colors_info=”{}”]<\/p>\n

Weak points<\/strong><\/h2>\n

[\/et_pb_text][et_pb_tabs active_tab_background_color=”#162d5c” inactive_tab_background_color=”#57728c” active_tab_text_color=”#FFFFFF” admin_label=”Register – Schwachstellen” _builder_version=”4.16″ _module_preset=”default” tab_text_color=”#FFFFFF” custom_margin=”|0px|||false|false” box_shadow_style=”preset2″ box_shadow_spread=”-10px” global_colors_info=”{}”][et_pb_tab title=”Background noise” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n

Even with Vol set to 0 the Pro Jr. exhibits an annoying 100Hz hum that can be attributed to a circuit fault as well as a grounding problem in some versions. All versions are affected by this, in my experience. This can be corrected by a change in the preamplifier and sometimes by removing the upper middle screw, but not always the latter. 1st point: more preamp filtering!<\/strong><\/p>\n

[\/et_pb_tab][et_pb_tab title=”Gain” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n

Somewhat annoying is the fact that the Pro Jr. already reaches volume saturation at volume 4, even with single coils. After that it’s just more gain coupled with more ambient noise. Most amps are operated somewhere between 1 and 2 and then are already too loud. Often the request arrives us whether we can install a powersoak – this helps, but does not solve the problem… In version IV the gain has been toned down a bit, which makes the amp seem more “playable” and sounds a bit more “open”. However, this is not 100% yet. So 2nd point: less gain!<\/strong><\/p>\n

[\/et_pb_tab][et_pb_tab title=”Tone control” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n

The excessive gain is also made worse by the fact that the tone control has been equipped with “wrong” component values. Of course it’s not completely wrong, it works but it can be done better anyway. The control acts in two directions: at the top it passes more treble and in the lower control range it takes away treble so that the sound becomes bassier. The upper range is too heavily dimensioned so that actually all frequencies are passed on and the volume control loses its effectiveness. And on the lower end the control takes away too little treble, so you have little influence on the shaping of the frequency band. This can be done better with selected component values. So 3rd point: better tone control!<\/strong><\/p>\n

[\/et_pb_tab][et_pb_tab title=”Jacks & knobs” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n

After a couple of years of use, the first weak points in the design become apparent: the amp cuts out sporadically! Most of the time the input jack comes detached from the board, so that no guitar signal can get into the amp at all, or the solder joints on the knobs break, resulting in loose contacts. The basic problem is that the components that are operated are soldered directlx to the board and at the same time have little or no support on the front panel (the input socket nut also tends to loosen…). This means that all force is transmitted directly to the solder joints. It’s cheap to produce, but it doesn’t last long. So 4th point: better fastening of bushing and knobs
.<\/strong><\/p>\n

[\/et_pb_tab][et_pb_tab title=”Tube failure” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n

The bottom side doesn’t look any better either: The tube sockets are soldered directly to the PCB, which isn’t bad at first, but the Pro Jr. can’t dissipate the heat because the soldering points are pretty thin and there’s no mass to dissipate the heat. The solder joints break down over time and cause loose contacts, failures, or even tube defects. So 5th point: better socket+surrounding!<\/strong><\/p>\n

[\/et_pb_tab][et_pb_tab title=”Idle current” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n

The high heat dissipation is also related to the usually very high quiescent current of the power amp tubes, because emphasis has been given primarily to production cost and less to longevity. With the bias set to high the amp does not sound bad but it wears out the tubes faster and can weaken surrounding components – but in return you can use all tubes and they sound good because they never run too cold… good for the crowd, but stupid for the user who has to live with the problems. Here’s the 6th point: install trim pot and adjust bias<\/strong>.<\/p>\n

[\/et_pb_tab][et_pb_tab title=”Components” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n

The components used are not that bad, except for a few electrolytic capacitors in early versions, which tend to break. What is annoying, however, is the fact that component replacement is really difficult because the PCB is not well manufactured, some conductive tracks come off the board and also the interconnects tend to break off because the cable that is used is too stiff. All this is not very service-friendly if you want to replace the electrolytic capacitors after a good 10 to 20 years. So point 7: new board and better\/new components.<\/strong><\/p>\n

[\/et_pb_tab][\/et_pb_tabs][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ admin_label=”Mod Bereich 1″ _builder_version=”4.16″ _module_preset=”default” custom_margin=”5px||5px||false|false” custom_padding=”0px||0px||false|false” global_colors_info=”{}”][et_pb_row column_structure=”3_5,2_5″ admin_label=”CSS Modifikationen” module_id=”Modifikationen” _builder_version=”4.16″ _module_preset=”default” module_alignment=”center” custom_margin=”0px|auto|0px|30px|false|false” custom_padding=”0px||||false|false” global_colors_info=”{}”][et_pb_column type=”3_5″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”\u00dcberschrift – Modifikationen” _builder_version=”4.16″ _module_preset=”default” custom_margin=”||5px||false|false” global_colors_info=”{}”]<\/p>\n

Modifications<\/strong><\/h2>\n

[\/et_pb_text][et_pb_text admin_label=”Text – Einleitung und Verbesserungen” _builder_version=”4.16″ _module_preset=”default” custom_margin=”-10px||||false|false” global_colors_info=”{}”]<\/p>\n

There are a few points on the amplifier that need to be improved. And these are all problems that occur more or less often and are the subject of complains. It’s not like we’re making all this up. But what we come up with are other improvements<\/strong> that the amp doesn’t have:<\/p>\n

[\/et_pb_text][et_pb_text admin_label=”Text – Einleitung und Verbesserungen” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n

Standby switch<\/h4>\n

For pauses, to replenish drinks, or to get a breath of fresh air, you’d be happy to switch to standby – if there was one. Unfortunately, the Pro Jr’s circuitry is not designed for this, mainly because it lacks a separate winding for the bias voltage in the transformer. Retrofitting in the existing circuit is quite costly, if it is not to be tied with inadequacies. So: Provide and install a good quality standby switch.<\/p>\n

[\/et_pb_text][et_pb_text admin_label=”Text – Einleitung und Verbesserungen” _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n

Adding a choke<\/h4>\n

As with many amplifiers, a choke in the amplifier’s power supply works miracles. More dynamics, better string separation and feel – actually exactly what you always want. I don’t know how many times we have already described the topic on the homepage, but it’s just like that, a MUST for every amplifier (imho).<\/p>\n

[\/et_pb_text][\/et_pb_column][et_pb_column type=”2_5″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_image src=”https:\/\/captain-guitar-lounge.com\/wp-content\/uploads\/2021\/09\/VerbranntesBoard.jpeg” title_text=”Burnt board” show_bottom_space=”off” align=”right” _builder_version=”4.16″ _module_preset=”default” max_height=”338px” max_height_tablet=”338px” max_height_phone=”338px” max_height_last_edited=”on|tablet” custom_margin=”0px||||false|false” global_colors_info=”{}”][\/et_pb_image][et_pb_text admin_label=”Worst Case” _builder_version=”4.16″ _module_preset=”default” text_font=”||||||||” text_orientation=”right” custom_margin=”||||false|false” global_colors_info=”{}”]<\/p>\n

Worst case: Burnt-out power tube board<\/em><\/p>\n

[\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section][et_pb_section fb_built=”1″ admin_label=”Vollbreit – Main Mod” _builder_version=”4.16″ _module_preset=”default” background_color=”gcid-ccfbcf15-fa71-4d0d-98f3-88576b9bbe68″ custom_padding=”5vh||5vh||false|false” global_colors_info=”{%22gcid-ccfbcf15-fa71-4d0d-98f3-88576b9bbe68%22:%91%22background_color%22%93}”][et_pb_row column_structure=”2_5,3_5″ admin_label=”Rundum-Sorglos-Paket” _builder_version=”4.16″ _module_preset=”default” background_color=”#FFFFFF” custom_padding=”15px|15px|15px|15px|true|true” border_color_all=”#0f1f40″ box_shadow_style=”preset2″ global_colors_info=”{}”][et_pb_column type=”2_5″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_gallery gallery_ids=”29513,29516,29332,29331,29330,29329,100909,100911,100913,100916,100918″ fullwidth=”on” _builder_version=”4.19.5″ _module_preset=”default” pagination_font_size=”0px” module_alignment=”left” max_height=”400px” custom_margin=”0px|20px||0px|false|false” custom_padding=”0px|||||” hover_transition_duration=”0ms” hover_enabled=”0″ border_color_right=”#0C71C3″ border_style_all_image=”none” global_colors_info=”{}” sticky_enabled=”0″][\/et_pb_gallery][\/et_pb_column][et_pb_column type=”3_5″ _builder_version=”4.16″ _module_preset=”default” background_enable_color=”off” custom_padding=”10px|10px|0px|10px|false|false” global_colors_info=”{}”][et_pb_text _builder_version=”4.16″ _module_preset=”default” text_orientation=”justified” custom_margin=”0px|0px|0px|0px|false|false” global_colors_info=”{}”]<\/p>\n

ALL-INCLUSIVE CAREFREE PACKAGE<\/h2>\n

The solution:<\/strong>To realize all the above points with the original board is an insane effort that is not really worth it. One or two of the points mentioned are quite doable, but if you want a really good amplifier that also lasts longer, you won’t get far with the original board. So a new board is needed! And at the same time you can take into account all the small errors and include improvements. And that’s what we do:<\/p>\n