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  • Re: Beolab Penta 6603 MK1 restoration project

    Well after a year and a half I finally was able to recover my amplifier from the shop I'd left it with. What an absolute nightmare. After paying them for the botched repair and bringing it back they said they would get it working. One excuse after another it just never happened. Looking at the amp as its been returned to me I can honestly say I don't see any evidence they did any further work on it. Now I'm in the same situation as so long ago, with a non functioning amplifier. The wife
    Posted to The Workbench (Forum) by StuckE30 on Sun, Jul 10 2016
  • Re: Beolab Penta 6603 MK1 restoration project

    Sorry for several months passing before an update, but I was waiting on someone else. I ended up dropping the amplifier off at a well regarded shop locally to have it looked at. The company I work for sends him assorted items to repair so I figured it would be worth a shot. It took him about 3 months to finally look at it and fix it. It looks like he replaced TR25 and TR30. Both replacements are Toshiba branded of the same part numbers. He said it was fixed so I picked it up. Upon getting it home
    Posted to The Workbench (Forum) by StuckE30 on Wed, Jan 7 2015
  • Re: Beolab Penta 6603 MK1 restoration project

    I haven't had any luck finding a superseded part of the transistors via google. Just a pile of links to Chinese junk knockoffs. While Google and the internet in general is a great resource sometimes seeking sage advice from an individual familiar with the exact product you're working on, more so familiar with the common failure modes of its components is infinitely more valuable. Where I'm sitting it seems prudent to replace all 8 transistors that are attached to the main heatsink body
    Posted to The Workbench (Forum) by StuckE30 on Fri, Oct 10 2014
  • Re: Beolab Penta 6603 MK1 restoration project

    No, I'm sure I've said as much earlier in this thread. I have an interest, learn quickly and have steady/capable hands. I knew I could handle the recapping of the crossovers and that is what I originally set out to do. That part is done and sounds great. I figured I would give repairing the amplifier a shot too, and that didn't go so well as to say I'm right back where I started. I assume the transistors need to be removed from the PCB to test across the leads. I don't know what
    Posted to The Workbench (Forum) by StuckE30 on Fri, Oct 10 2014
  • Re: Beolab Penta 6603 MK1 restoration project

    OK so please correct me if I'm wrong but TR25-27 (SC3281) and TR30-32 (SA1302) are the output transistors? Initial investigation looks like both of those transistors are NLA from Toshiba and difficult to source unless you want the cheap Chinese knockoffs. (I don't) Which are the drivers? What is the constant current generator? I have spare emitter resistors to replace R99/R100, everything was ordered in double quantity to give the other amplifier the same upgrades.
    Posted to The Workbench (Forum) by StuckE30 on Fri, Oct 10 2014
  • Re: Beolab Penta 6603 MK1 restoration project

    I'm not too worried about the small amount of money put into the amplifier components. 90% of the monetary investment was in the crossovers, and ultimately if I can't get the amplifier working I will run the towers bypassing the amplifier. As for finding the actual problem I fear quickly this will fall outside my scope. My diagnostic equipment is limited to a digital multimeter. I'm not sure which transistors are output vs. driver. I'm also not sure how to go about testing any of
    Posted to The Workbench (Forum) by StuckE30 on Fri, Oct 10 2014
  • Re: Beolab Penta 6603 MK1 restoration project

    Well sorry for the lack of updates, not that I think anyone is on the edge of thier chair to hear about whats come of this project... but some things came up in life and I had to box the parts up for a few weeks. This evening I soldering in the last capacitor I had been waiting on, I referenced my photos of the untouched board and checked it against my work to make sure each capacitor was correct and not reversed. All was well, so in my case anyway the PCB was labeled correctly. I attached test leads
    Posted to The Workbench (Forum) by StuckE30 on Fri, Oct 10 2014
  • Re: Beolab Penta 6603 MK1 restoration project

    While I'm certainly not going to argue with any of the points you've made the fact remains that the components are bought, paid for, and installed. No sense doing anything else at this point. I was aware of that fact that only one of the 68uF caps needed to be changed but I'm a little OCD and can't have things I'll likely never see again mismatched. I doubt such a personal problem is uncommon around here. I haven't had a chance to power up and set the trimmer pots yet as more
    Posted to The Workbench (Forum) by StuckE30 on Wed, Sep 10 2014
  • Re: Beolab Penta 6603 MK1 restoration project

    I finished up both boards, PCB 14 and PCB 15. I got them reinstalled into the housings, I did have to trim the inner stiffening ribs just a touch on one side to make enough room for the 2 68uF caps to nestle down in there. They are pinched between the baffle foam and the PCB so they are nice and secure. Still waiting on those red wima's from Mouser so I screwed the base plate back on and connected the tower up to the Yamaha reciever I have out in the garage for car work tunes. Figure 50w rms
    Posted to The Workbench (Forum) by StuckE30 on Sun, Aug 31 2014
  • Re: Beolab Penta 6603 MK1 restoration project

    No, not at all. Many snags, tears etc. I'm not concerning myself much with cosmetics as of yet. Focusing first on getting them functioning as they should.
    Posted to The Workbench (Forum) by StuckE30 on Fri, Aug 29 2014
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