WAIVER AND SECOND AMENDMENT TO AMENDED AND RESTATED REVOLVING CREDIT AGREEMENT

Exhibit 10(ac)(2)

WAIVER AND SECOND AMENDMENT TO

AMENDED AND RESTATED REVOLVING CREDIT AGREEMENT

This Waiver and Second Amendment to Amended and Restated Revolving Credit Agreement (this “ Amendment ”) is entered into as of August 24, 2005 (the “ Effective Date ”) by and among (i) Richardson Electronics, Ltd., a Delaware corporation (the “ US-Borrower ”), (ii) Burtek Systems, Inc., a Canadian corporation, Richardson Electronics Canada, Ltd., a Canadian corporation (each a “ Canada-Borrower ”, and collectively, the “ Canada-Borrowers ”); (iii) Richardson Electronics Limited, an English limited liability company (the “ UK-Borrower ”); (iv) RESA, SNC, a French partnership, Richardson Electronique SNC, a French partnership, Richardson Electronics Iberica, S.A., a Spanish corporation, Richardson Electronics GmbH, a German limited liability company, Richardson Electronics Benelux B.V., a Dutch private limited liability company, (each a “ Euro-Borrower ” and collectively, the “ Euro-Borrowers ”), (v) Richardson Sweden Holding AB, a Swedish corporation (the “ Krona-Borrower ”) and (vi) Richardson Electronics KK, a company organized under the laws of Japan (the “ Japan-Borrower ”) (the US-Borrower, the Canada-Borrowers, the UK-Borrower, the Euro-Borrowers, the Krona-Borrower and the Japan-Borrower are collectively referred to as the “ Borrowers ”), the lenders party hereto (each, a “ Lender ” and collectively, the “ Lenders ”), JP Morgan Bank, N.A., London Branch, as Eurocurrency Agent (the “ Eurocurrency Agent ”), JPMorgan Chase Bank, N.A., Canada Branch as Canada Agent (the “ Canada Agent ”), JPMorgan Chase Bank, N.A., Tokyo Branch as Japan Agent (the “ Japan Agent ”) and JPMorgan Chase Bank, N.A., successor by merger to Bank One, NA as administrative agent (in such capacity, the “ Administrative Agent ”) (the Eurocurrency Agent, the Canada Agent, the Japan Agent and the Administrative Agent are collectively referred to as the “ Funding Agents ” and each individually a “ Funding Agent ”).

RECITALS

WHEREAS, the Borrowers, the Lenders and the Funding Agents are parties to that certain Amended and Restated Revolving Credit Agreement dated as of September 29, 2004 (as amended from time to time, the “ Agreement ”);

WHEREAS, the Borrowers, the Lenders and the Funding Agents desire to amend the Credit Agreement in order to revise certain financial covenants, adjust pricing for loans and other financial accommodations and to provide certain requirements for the maintenance of excess Borrowing Base availability, in each case on the terms and conditions set forth herein;

WHEREAS, the Lenders wish to waive certain Events of Default arising from the US-Borrower and its Subsidiaries’ failure to satisfy certain requirements in respect of their Fixed Charge Coverage ratio for the quarter ended May 31, 2005, on terms and conditions set forth herein;

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NOW, THEREFORE, in consideration of the premises and mutual covenants contained herein, the parties hereto agree as follows:

1. Defined Terms . Capitalized terms used herein but not defined herein shall have the meanings ascribed thereto in the Agreement, as amended hereby.

2. Waiver .

Each Lender hereby waives Events of Default under Section 7.3 of the Agreement arising solely from the failure of the US-Borrower and its Subsidiaries to maintain the Fixed Charge Coverage ratio required by Section 6.35 of the Agreement solely in respect of the fiscal quarter ended May 31, 2005.

3. Amendments .

(a) The definitions of “Availability Hold” and “EBITDA” contained in Section 1.1 of the Agreement are hereby deleted in their entirety and replaced as follows:

“ ‘Availability Hold’ means the sum of Twenty Three Million Dollars ($23,000,000).”

“‘ EBITDA ’ means, as at any date of determination thereof, the sum of Net Income, Interest Expense, income taxes, depreciation and amortization in each case as calculated as at such date of determination for the US-Borrower and its Subsidiaries on a consolidated basis in accordance with Agreement Accounting Principles. Neither cash nor non-cash charges reflecting extraordinary terms, unusual items, or one-time charges will be added back for purposes of the EBITDA calculation. Cash and/or non-cash gains reflecting extraordinary terms, unusual items or one-time gains will be subtracted for purposes of the EBITDA calculation.”

(b) The first sentence of Section 6.2 is deleted in its entirety and replaced as follows:

“Each Borrower will, and will cause each Subsidiary to, use the proceeds of the Advances and Facility Letters of Credit for general corporate purposes.”

(c) Section 6.23 is hereby deleted in its entirety and replaced as follows:

6.23 Repayment of Subordinated Debt; Adjustment to Pricing .

6.23.1 Until all Obligations have been irrevocably paid in full, the US-Borrower and its Subsidiaries shall not make any payment upon any principal of any Subordinated Debt, including by means of repurchasing Debentures; provided that the US-Borrower shall be permitted to repay or repurchase and retire, in each case at a price that is at or below the par value for such Identified Debenture (plus an amount equal to

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the accrued and unpaid interest to date of repayment, repurchase or retirement), an aggregate amount of the Identified Debentures of up to the Repurchase Amount prior to June 10, 2006 pursuant to open-market transactions, in privately-negotiated transactions, by repayment or otherwise (the “ Debenture Retirement ”) provided further that the Debenture Retirement shall be effected solely by either or both of an offer to exchange Identified Debentures for new debentures (“ New Debt Securities ”) or repayment or repurchase of the Identified Debentures by the issuance of New Debt Securities, which New Debt Securities shall constitute Subordinated Debt and shall otherwise be issued on terms acceptable to the Administrative Agent and the Required Lenders. Notwithstanding anything to the contrary in this Agreement, no payment upon any principal of any Subordinated Debt, no sinking fund payment and no repurchase or retirement of Subordinated Debt may be made at any time when there exists any Default or Unmatured Default or when such payment, repurchase or retirement would result in any Default or Unmatured Default (including pursuant to Section 6.24 or 6.25 ).

6.23.2 In the event the US Borrower shall fail to repay, repurchase or retire the Identified Debentures in accordance with the terms of Section 6.23.1 hereof (and without limiting recovery of additional interest that may occur upon the occurrence of a Default), except for the Applicable Margin associated with the Floating Rate, each Level of the Pricing Schedule shall be increased by one quarter percent (.25%) above the otherwise Applicable Margin effective on November 30, 2005 and by an additional one quarter percent (.25%) above the otherwise Applicable Margin effective February 28, 2006 in each case which adjustments shall continue until the completion of the Debenture Retirement.

(d) Sections 6.24 and 6.25 are hereby deleted in their entirety and replaced as follows:

6.24 Leverage Ratio . The US-Borrower and its Subsidiaries will maintain, on each date listed below, a Leverage Ratio of less than the respective ratio specified for such date:

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6.25 Fixed Charge Coverage Ratio . The US-Borrower and its Subsidiaries will maintain, on each date listed below, a Fixed Charge Coverage Ratio greater than the respective ratio specified for such date:

(e) The date “February 28, 2006” is hereby deleted from Section 6.27 and replaced with the date “June 10, 2006.”

(f) A new Section 6.29 is hereby added as follows:

“6.29 Excess Availability The Borrower will at all times through and including the later of (i) August 31, 2006 or (ii) the submission of financial reports to the Agent required by this Agreement in respect of the Borrower’s fiscal year ended May 31, 2006, maintain Borrowing Base in excess of outstanding Loans and Facility Letters of Credit in an amount not less than the Availability Hold, provided that this covenant shall remain in effect at all times after such dates if a Default or Event of Default shall exist on or before any such date.”

(g) Annex A (Pricing Schedule) is hereby deleted in its entirety and replaced in the form attached hereto and made a part hereof. The undersigned parties hereby confirm that, based on the most recent financial reports submitted by the US Borrower to the Administrative Agent, as of the Effective Time, all Advances shall be priced at Level V Status within the meaning of the Pricing Schedule.

4. Effectiveness . This Amendment shall become effective when the Administrative Agent has received all of the following acknowledged to be satisfactory by the Administrative Agent:

(a) This Amendment, executed by the requisite signatories;

(b) A certificate, signed by the chief financial officer of Richardson Electronics, Ltd. substantially in the form of Annex A