Goldstar MBM-2105GIA Circuit Description, Video Amplifier, Power Supply, To CRT CA.THODE

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CIRCUIT DESCRIPTION

1.VIDEO AMPLIFIER

The Fig. 3 details the cascade video amplifier. Video amplification is provided by the TR303 and TR304. TR303 and TR304 are connected in a cascade configuration. TR303 operates as a common emitter and TR304 operates in the common base configuration. This minimized the miller effect input capacitance and the difining breakdown parameter for TR303 which becomes BVCBO as opposed to BVCEO.

This enables selection of a higher speed/lower breakdown transistor to be used in the video amplifier.

The emitter of TR304 is driven by the collector of TR303 which is a high frequency transistor. Overall voltage gain for the stage is determined by the ratio of R312 to R316. Bandwidth is within 3dB to 32 MHz.

2.POWER SUPPLY

The 120V AC line voltage is applied to the primary of the T901 where it is stepped down through the secondary winding to approximately 17V (AC). After passing through the bridge rectifier circuit and filter (C905) the regulated DC supply voltage is approximately 18V (DC). The 18V unregulated B+ voltage is applied directly to the collector of the B+ regulator (TR901). A voltage divider network (R905, VR901, R906) in which the B+ adjustment control (VR901) is used to establish the desired operating level (12V DC). When AC input voltage variations occur, a correction voltage is produced at the base of TR903 and is coupled directly to the base of the error amplifier (TR902). This correction voltage is then passed from the emitter of TR902 directly to the base of TR901 and B+ voltage regulation is then accomplished.

R314

TO@ < ;

+

c305

lOOuF/‘16V

T R 3 0 4 KTC2229

R316 L301

1.ZK/ZW 4.7uH

• TO v

70

+

2~ C308 2.2uFll oov

• TO CRT CA.THODE

R317

3 3 0

3 T R 3 0 3

TO @

2N3904

R309

7 5C306 12OP

R313

4 7

Figure 3, Video Ampllfler

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Contents GolclStar Before Servicing the CHASSIS, Read the SafetyPower PUSH-ON FeaturesTo CRT CA.THODE Power SupplyCircuit Description Video AmplifierComposite Video Input and HORIZONTAL/ Vertical Deflection Composite Video Input PIN Line H Oscillator PINFramev Oscillator PIN Horizontal Size L703 AdjustmentCentering Adjustment Vertical Size VR601Tolerance Unless Otherwise Noted AibicOefl Capacitors are Shown01G.h R719 DiagramREG Circuit ~ Troubleshooting GuideMain PCB Printed Circuit BoardMain PCB Solder Side Line Filter PCB Solder Side Replacement Parts List Mechanical Parts Exploded ViewIE if Replacement Parts List Neon Lamp 20-0040

MBM-2105GIA specifications

The Goldstar MBM-2105GIA is a standout model in the realm of commercial refrigerators, offering a blend of innovative technology, robust construction, and user-friendly features that make it an excellent choice for restaurants, cafes, and other food service establishments.

One of the main features of the MBM-2105GIA is its spacious interior, which is designed to accommodate a significant volume of products. It boasts a large storage capacity, with multiple adjustable shelves that allow businesses to customize their layouts according to their specific needs. The unit is engineered with a stainless steel exterior, which not only delivers an aesthetically pleasing look but also ensures durability and resistance to corrosion.

This refrigerator includes advanced cooling technology, utilizing a high-efficiency compressor paired with a fan-assisted cooling system. This setup guarantees consistent temperatures throughout the unit, effectively maintaining food safety standards. The digital thermostat provides precise temperature control, allowing users to monitor and adjust the settings easily as needed.

Moreover, the Goldstar MBM-2105GIA is designed with energy efficiency in mind, which is a critical factor for commercial applications. It meets strict energy performance standards, helping businesses save on electricity costs while reducing their environmental impact. The appliance is insulated with high-density polyurethane, promoting better energy retention and minimizing energy loss.

Another noteworthy characteristic of the MBM-2105GIA is its user-friendly features, such as a self-closing door with a magnetic gasket that ensures an airtight seal. This design prevents temperature fluctuations and energy wastage. The unit also includes internal LED lighting, providing excellent visibility for staff to easily identify stock without having to open the doors frequently.

In terms of maintenance, the model offers easy access to components for cleaning and servicing, minimizing downtime and ensuring longevity. The versatile design and reliable operation make the Goldstar MBM-2105GIA an invaluable asset in any commercial kitchen, combining practicality with performance to support various food preservation needs.
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