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Case 645432 . 02.04.2023. Marantz 2275 receiver repair. No sound.

Case 645432 . 02.04.2023. Marantz 2275 receiver repair. No sound. Poor front panel illumination.
Problem solved by cleaning push switch “Tape1” on front panel. Deoxit spray used (needle injection inside switch ) . Illumination lamps changed to LED lamps by customer request.

Some technical experience and view to share about front panel illumination lamps. LED or original incandescent lamps ? Which one is better ? Are there any advantages ?

Some customers like LED , some original incandescent lamps. We provide pictures for comparison LED and old school lamps illumination. In this case we compare 8 volt lamps for Marantz 2275 front panel illumination.
On picture right meter illuminated by LED lamp, left meter by original incandescent old school lamp and small function lamps illumination to compare.

How LED design lamp works – electrical current goes to special microchip inside with semi-conducting material layers and produce visible light.

How old school incandescent lamp design works – electrical current goes to the tungsten filament inside lamp and start burning tungsten metal process, producing visible light. Basically you see light from burning metal named tungsten in no oxygen glass tube or sphere.

LED lamps pluses –
1. More brightness 20 -70 %.
2. Longer work life time 70-300% .
3. Ability to choose from many colors and light tones ( white, warm white , cold white, blue, light blue, icy blue ,dark blue …………….)
4. Lower electric current to produce same brightness 30-200 % (your electric consumption lower means your electric bill is lower ,not significant amount but still good news ).
5. Lower heat generation 20-80% .
6. No need to keep inert gas and no oxygen condition inside glass lamp like inside old incandescent lamp .
7. Big variety of shapes and designs.

Minuses for LED lamps .
1. AC or DC application (polarity) importance for some lamps.
2. Lower and limited light producing angle on some LED lamps, instead 270-360 degree wide angle on old school lamps you getting 60-180 degree direct light angle only. In some application it is extremely important.

Both type of lamps don,t like over voltage . They will stop working in short period of time if you apply bigger voltage then they designed for.
All old school incandescent lamps are universal AC or DC voltage and wide light angle by design.


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Case 453434. 02.03.2023 . Sansui 2000x receiver repair. Right channel is scratchy sound , thunderstorm sound on minimum volume level.

Case 453434. 02.03.2023 . Sansui 2000x receiver repair. Right channel is scratchy sound , thunderstorm sound on minimum volume level.
After applying heat and cold to all transistors in filter and driver sections found bad transistor 2sc458, position tr806, driver board f-1180.
Problem solved by replacement.
Pluses – simplicity, functions and boards separation ,easy to work on it.
Minuses – speaker plugs design on back panel (easy to break).

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Case 4563728 . 02/01/2023 . Marantz PM-5 amplifier repair .

Works on maximum volume level only and no left channel.
Protection relay replacement solved problem.
Pluses – good attention to phono input. MC and MM phono inputs available.Good for phonograph players .Support MM and MC phonograph cartridges. Massive heat sink inside , good and stable sound.
Minuses – chaotic board management design inside, sandwich boards installation in central area with overheating on bottom board.

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Repair case 4657687. 01/20/20223 Pioneer QX-9900 quad receiver

Case 4657687. 01/20/20223
Pioneer QX-9900 quad receiver.Distorted sound after 20 minutes.
Cleaning all front panel switches and control pots solved the problem.
Technical view feedback – nice unit , build to last long time , perfect modules separation for prive nting signal interference between modules, plus each section has own shield cover, multi-voltage transformer let you use this unit in any country around the world without modification , good quality components in use, good heat sink design, stable sound at any power level.
Minuses- hard to get to front panel switches and pots in case if they need replacement.

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Repair case # 125432. Pioneer SA-9500II amplifier – no sound, keeps blowing main fuse.

Repair case # 125432. Pioneer SA-9500II amplifier – no sound, keeps blowing main fuse.
4 Output transistors and main fuse replacement solved the issue.
Instead original transistors we installed MJE15032G / MJE15033G Transistors NPN/ PNP. Works even better then originals.( same terminal design, same configuration) . Main fuse- 4-6 Amp.
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