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  #16  
Old 12-24-2016, 11:57 PM
old_coot88 old_coot88 is offline
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Quote:
Originally Posted by Jon A. View Post
Is the thermistor that big black disc? I think it's fine, it was just caked in dust.
No, the thermistor is the little bitty metallic looking disc next to it. If it goes open, the big black thingy (VDR- voltage dependant resistor, or varistor) will cook, fry, sizzle, smoke, and drip stinky mung. Hey, learned a new word from Zeno.
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  #17  
Old 12-25-2016, 12:17 AM
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Quote:
Originally Posted by old_coot88 View Post
No, the thermistor is the little bitty metallic looking disc next to it. If it goes open, the big black thingy (VDR- voltage dependant resistor, or varistor) will cook, fry, sizzle, smoke, and drip stinky mung. Hey, learned a new word from Zeno.
Oh well, I doubt it would out-stink a blown selenium rectifier, or even come close to that.

I wiped off both discs. Not sure what to think of the thermistor...
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File Type: jpg GR-2000 power supply module 2.jpg (90.8 KB, 31 views)
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  #18  
Old 12-25-2016, 02:00 PM
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Figured out the oddball varactor tuner/OSD and got it on channel 3 for a DVD feed. I hooked up a speaker, sound works. It looks pretty bad, but it's a start.
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File Type: jpg Heathkit GR-2000 demo.jpg (81.9 KB, 44 views)
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  #19  
Old 12-25-2016, 04:44 PM
zeno zeno is offline
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Quote:
Originally Posted by Jon A. View Post
Figured out the oddball varactor tuner/OSD and got it on channel 3 for a DVD feed. I hooked up a speaker, sound works. It looks pretty bad, but it's a start.
That is NOT a bad start ! Strong jug. Looks like blue convergence
is way off on bottom right.

73 Zeno
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  #20  
Old 12-25-2016, 10:54 PM
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Ah, I didn't mean it was a bad start, just that it looks kind of bad because I haven't done any setup adjustments. I just changed a couple of jumpers and dialed in the channel. Often times the picture gets skewed horizontally or shifts vertically so that the two halves of the image are in the wrong places, but hey, it's working.
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  #21  
Old 12-26-2016, 06:49 AM
kf4rca kf4rca is offline
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One of the problems with those modular sets is intermittent connections. When you put the set in its final position, you need to re-seat all the modules.
At one time, all manufacturers made modular sets. But it was soon discovered that all the connections created intermittent problems. So they returned to a unitized chassis design.
To create a video input, you'll need to go in at the emitter of Q312 with 3.5 Volts P-P on non-inverted video.
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  #22  
Old 12-27-2016, 02:54 AM
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I'll do that, and re-seat the ICs and other transistors as well. May as well try the same with the 370, it may get high voltage back. If not, who knows what other ills it has that might be cured.

I found a S-video mod for the 2000, I'll probably go all out and try that.
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  #23  
Old 12-27-2016, 06:48 AM
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Had a heath scope that had issues with IC socket intermittents, before I was acquainted with contact cleaner...Did not keep it long.
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  #24  
Old 12-27-2016, 09:01 AM
kf4rca kf4rca is offline
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What coil did you say was broken? If its on the IF board, you may not need it if you are going to convert to A/V input.
For a video input, you can use a video buffer IC or you can use 2 transistors. One transistor will not do it since you need more than 1V of video. An emitter follower will give non-inverted video but with no gain. So you will need a two transistor design called a compound pair.
Here's the circuit I used.
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  #25  
Old 12-27-2016, 12:35 PM
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Excellent, thanks.

The broken coil is on the chroma board.
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File Type: jpg Heathkit GR-2000 broken coil.jpg (96.4 KB, 25 views)
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  #26  
Old 12-27-2016, 12:46 PM
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If it is JUST a coil and not a transformer, then you may be able to rewind it. just unwind, glue the form back together, and rewind.
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  #27  
Old 12-27-2016, 03:50 PM
kf4rca kf4rca is offline
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If that doesn't work, you can probably salvage a coil from an RCA of the same vintage.
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  #28  
Old 12-28-2016, 12:28 AM
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I'd rather put in another one really. Would one from a CTC-88 work? I have one from September 1978. I wouldn't be junking it, just borrowing a coil. Also, are there any Heathkit manuals available for download?
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  #29  
Old 12-28-2016, 07:15 AM
kf4rca kf4rca is offline
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Its probably the coil. It sticks out like a sore thumb. The transformer has a shield around it.
Most likely the CTC-88 coil will work. The chip used is an RCA CA3071. It was also manufactured by Motorola as the MC1371. It was part of a very popular chipset:
http://www.ralphselectronics.com/pro...EMI-CA3071.PDF
The manuals are assembly for the most part and since yours is already assembled, they're not needed. The schematic is a large 24x30 sheet.
BUT that set is legacy technology so you shouldn't need a schematic.
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  #30  
Old 12-28-2016, 03:22 PM
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The coils in the CTC-88 look a little small. The base of the broken one is marked 40 with 1649 under that. Any idea what would replace this?
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