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Post by stixsigma on Jan 2, 2013 9:24:41 GMT -5
jaaap,
Thanks for the great info. I am in the States - I take it you're in the UK, yes?
While I was away from work I heard back from W D Greenhill in Essex. They quoted me AY-1-5050 at 13.13 GBP and SAJ180 at 24.95 GBP. Ouch.
When looking at the ICs in my organ, I noticed that there is a mix of these two chips. Do you know if they can be used interchangeably? I'm assuming so, but don't want to proceed on an incorrect assumption.
I happened to find a repair manual on eBay and have been poring over that figuring out how best to plan my repairs. I will probably scan that and make it available through this site if I can figure out how to do so.
I do have one other question: after play-testing to see if I had issues with either dividers (probably) or oscillators (almost definitely with G), I noticed that the upper notes of some of the even footings were not in tune with their counterparts in lower octaves, which were all in tune. Do you have any idea why that might occur?
Cheers!
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Post by stixsigma on Jan 4, 2013 13:23:15 GMT -5
I found out that there are several IC chips that can be used interchangeably: AY-1-5050, SAJ180, SAA1005 and SFF 5002.
I spent a lot of time last night thoroughly cleaning all the key contacts underneath the upper manual keys. Wow that was tedious. The organ just felt better when I tested it afterwards. Some of the issues I'd had went away. The problems with G not playing didn't but they did change. Instead of a low growl, there is now just an intermittent clicking any time I play any octave G in 2' flute.
I had trouble cleaning the highest C key contacts, so that could have something to do with this. Also, I realize I need to clean all the drawbar contacts. Maybe this will fix it.
In the meantime I ordered six AY-1-5050 chips and hope this is enough to tide me over for a while.
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Post by Nick on Apr 23, 2013 14:20:50 GMT -5
Hi,
I'm also trying to repair a Farfisa VIP organ but I would like to replace the scarce frequency divider chips with new chips.
So far, I've mounted and rewired two CD4520 chips together to replace one AY-1-5050 chip. I've got some signal coming out of these chips but it does not track very well so the sound is a little scrambled.
Does anybody has an alternative solution for these chips?
Nick
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Post by gsc on Jul 5, 2013 4:55:13 GMT -5
Hi, sorry to dig up an old thread again but I have a problem with a Farfisa 345.
The problem is some of the notes sound really low and distorted then when I change the draw bar on the same bank to a different harmonic/divide/pitch some notes will be ok. I have replaced several of the AY-1-5050 chips and swapped them around but still no improvement. Any help is much appreciated, GSC.
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Post by kurt on Aug 27, 2014 10:44:09 GMT -5
I have one of these (VIP 600) which looks and feels mint, but makes no sound. Lights up, no sound. Help me.
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Shirk studios - Chicago
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Post by Shirk studios - Chicago on Jun 23, 2018 9:48:29 GMT -5
My Farfisa 345 uses the same divider chips. There is a guy who makes work-alike boards that plug into the IC socket and he sells them for $35. Can't remember the website. When I bought my 345 it actually had one of them installed. It uses two 4520 ic's to divide and a hex inverter chip to square off and sine wave inputs. It wouldn't be too difficult to build your own.. I’m currently repairing a VIP500. I had one or two bad Frequency Divider chips (mine are Texas Instruments TMS3848NC IC’s) I ordered replacements (AY-1-5050) from a very kind vendor in Italy. They arrived and worked perfectly for a few days. Then the two NOS AY-1-5050’s died. Original TMS3848’s are still working fine. All oscillators are tested and working perfectly. I should mention, I did recap the power supply and it seems to be behaving well. Delivering a consistent 11.7v on the 12v rail and -14.78v on the -15v rail to the IC’s. Since these NOS chips are kind of pricey and apparently not too reliable, I’m very interested in this DIY 2x5420 chip idea. However I cannot find anything about it onlinez vendors or DIY plans. Any ideas? Thank you, Stephen Shirk SHIRK studios - Chicago -USA
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Greetings from Istanbul
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Post by Greetings from Istanbul on Jan 11, 2022 0:09:48 GMT -5
My Farfisa 345 uses the same divider chips. There is a guy who makes work-alike boards that plug into the IC socket and he sells them for $35. Can't remember the website. When I bought my 345 it actually had one of them installed. It uses two 4520 ic's to divide and a hex inverter chip to square off and sine wave inputs. It wouldn't be too difficult to build your own.. I’m currently repairing a VIP500. I had one or two bad Frequency Divider chips (mine are Texas Instruments TMS3848NC IC’s) I ordered replacements (AY-1-5050) from a very kind vendor in Italy. They arrived and worked perfectly for a few days. Then the two NOS AY-1-5050’s died. Original TMS3848’s are still working fine. All oscillators are tested and working perfectly. I should mention, I did recap the power supply and it seems to be behaving well. Delivering a consistent 11.7v on the 12v rail and -14.78v on the -15v rail to the IC’s. Since these NOS chips are kind of pricey and apparently not too reliable, I’m very interested in this DIY 2x5420 chip idea. However I cannot find anything about it onlinez vendors or DIY plans. Any ideas? Thank you, Stephen Shirk SHIRK studios - Chicago -USA Same issue here during restoring a VIP600. I'll try the same way. Please keep on sharing ideas here...
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