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Old 12-06-2018, 05:41 AM
AlanInSitges's Avatar
AlanInSitges AlanInSitges is offline
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Join Date: Nov 2017
Location: Sitges, Catalonia, Spain
Posts: 446
Help with a B&K 1077PAL

Yes, really, they exist, and I have one!




I bought this online from a--well, basically, a junk dealer. He got it from another junk dealer, and had no idea if it worked or not (spoiler: it does not).

The only reference to this thing I can find online is the ad I bought it from. No schematics, manuals, nothing of the sort.

I was excited to get this, hoping to have a signal source to start work on this growing pile of TVs in my garage. It has a Type B (US-style) grounded plug with the ground pin cut off, and this notice printed on top:



There is no means to switch voltages that I can find. And the power supply looks pretty much like the one in the schematic for the 1077B that's out there on the net, so I can't figure out how this thing is supposed to work over such a huge range of voltages. Based on the plug, I'm planning to stick to 120V for the time being.

I tried to bring it up on a variac (following Phil's excellent-as-always article on his 1077) and...dead. I checked the fuse and here is our first sign of trouble:



But it has continuity, and in theory ought to power up, so I took off the bottom. Shit.




The HV rectifier socket has a big hole burned through it. At first I thought it had arced, but there is no sign of any arcing on the socket itself, so I figure it may be ancillary damage from when that green thing that used to be a resistor burned up.

It also appears to have had a number of the power supply components replaced with contemporary diodes and electrolytics:



So, I have some questions:

- The line voltage has me really perplexed. I've gone through it again just now, and the power cord pretty much goes right to the primary of the transformer, no 110/220 switch that is typical of European products from this era. Any ideas here?

- I'll start troubleshooting around that burned up resistor and hopefully the schematic will be close enough to follow along, and figure out what caused that to happen, but what about that giant hole in the HV rectifier socket? Scrape out the carbon and goop it with silicone, or do I need to try to replace it? Finding another one will be a challenge.

- Several of the electrolytics have been replaced, but the main filter in the can and the ones on the PCBs are all original - is it safe to assume I need to replace all of those?

- The flyback looks to have been pretty toasty during its life, is this normal for one of these? I don't have a ringer but can ohm it out to get an idea if it's open or not.



Any suggestions, advice or other comments are most welcome!

Last edited by AlanInSitges; 12-06-2018 at 05:53 AM.
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