Repairing an vintage analog delay

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TheKoala
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Post by TheKoala »

Good morning everyone !

I got an old analog delay from an uknown brand - "Nashville", made in Japan. It has a Reticon R5101 2000-stage chip in it as its delay line. I am starting to get used to building and repairing BBD-based delays but this one is weird ! It seems that I can't have any signal out of either output of the delay chip, but the input is behaving properly. Also, the clock is running well looking at it on my scope, behaving properly.
Attached, pictures of the inside board (to see how it looks) and the controls. The "delay shift" control changes the speed of the delay clock. I only get dry signal through at the time, the input level control and the "Output L/H" control both work fine. The speend control does change the frequency of the clock correctly.
Would I be right to assume that this R5101 chip is dead ? If so, it is really unfortunate, but I will certainly remove it and hack the circuit to work with a v3208 (2048-stage BBD chip) because of how glorious this pedal looks.
(Please don't mind the blue pot, I removed it and put back the original resistors - was trying to modify the bias a bit to see how it was behaving, still nothing unfortunately)

Thank you very much !
Regards,
Rodolphe
IMG_20201105_182851.jpg
IMG_20201105_185450.jpg

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plush
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Post by plush »

TheKoala wrote: 05 Nov 2020, 18:01 It seems that I can't have any signal out of either output of the delay chip, but the input is behaving properly.
Dead reticon. Bye, chipie.

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TheKoala
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Post by TheKoala »

Well that's a shame, what a nice looking pedal ! I guess I will have to hack it for another chip now...
Does anyone else have any suggestion about additionnal tests I should perform on the chip or if it is indeed dead ?

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plush
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Post by plush »

TheKoala wrote: 05 Nov 2020, 19:41 Does anyone else have any suggestion about additionnal tests I should perform on the chip or if it is indeed dead ?
Make sure reticon has proper vcc/vdd and nothing is connected to it's outputs and then probe them once again.

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TheKoala
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Post by TheKoala »

It has Vbias correctly applied from resistors (voltage dividers) to get about the same bias voltages as per the earlier MXR green delay schematics. Each output has a 2k2 isolating resistor + a trimpot to cancel out the clock signal bleeding through, and it does have the correct 12V power supply applied to it... Guess it will head to the bin or in a frame to hang on the wall !

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TheKoala
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Update : delay chip carefully removed and circuitry hacked for a CoolAudio v3208 as planned. The delay now works wonder. I changed a bit the clock so that the delay can get slightly longer but that thing is either designed for reverb-like trails or slapback delay. Also planning on putting back the battery clips when my Tayda order arrives.

Thanks Plush for your help !

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TheKoala
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Post by TheKoala »

Update : it seems like this pedal is based on the Coron/Grant Analod Delay AD-500. Good to know !

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TelboyD
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Post by TelboyD »

TheKoala wrote: 06 Nov 2020, 17:50 Update : delay chip carefully removed and circuitry hacked for a CoolAudio v3208 as planned. The delay now works wonder. I changed a bit the clock so that the delay can get slightly longer but that thing is either designed for reverb-like trails or slapback delay. Also planning on putting back the battery clips when my Tayda order arrives.

Thanks Plush for your help !
Hi... earlier this week I received the bad news from my repair guy that the Reticon R5101 in my 'Carlsbro Echo' (that I've used since the 80s) is kaput, so I thought it best to check here, et voila!

Is there a possibility that the pedal can be saved with the CoolAudio v3208, and, if so, could you possibly help show me 'the hack' you used to save yours, please (if I order a couple from ebay)? Any help would be very much appreciated as I miss my slapback! Tried tons of delays and nothing else came close (except a Memory Man, and that's out of my price range). Cheers, Tel.

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