ARP 1601 clone Build Thread

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elmegil
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Re: ARP 1601 clone Build Thread

Post by elmegil » Mon Jan 27, 2020 12:10 pm

Need to be looking at Z1 A/B/C/D (pins 3, 4, 10, 11), Z2 (pin 11, possibly 8 or 10, and 13) and TP2 (which should be the same as Z2 pin 13).


Note that Z1 is a CD4011, which is a quad NAND even though the gates are drawn in the schematic as inverters. A NAND with both inputs tied to the same value acts as an inverter.

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Re: ARP 1601 clone Build Thread

Post by solar1 » Mon Jan 27, 2020 12:23 pm

I attached the best photo of the scope I could do with my old crap camera TP 18 & 19

upon a closer look, I almost think the sample timing of off.
I have to say, this is beyond my level so I really don't know what im looking at.
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Re: ARP 1601 clone Build Thread

Post by solar1 » Mon Jan 27, 2020 12:41 pm

Adjusting the 2 sliders, I was able to get the waveform to look like the service manual diagram
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Re: ARP 1601 clone Build Thread

Post by elmegil » Mon Jan 27, 2020 12:47 pm

Yeah, that looks good for TP18. And the TP20 pulses are around 70usec?

What does the voltage look like at pin 3 of Z32 / Z33?

You don't really want to measure the cap directly, because the load of the scope probe can drain the cap. If you want to, use a 10x probe if possible.

Outputs (pin 1) of Z34 & Z35 would also be a good place to measure, that should let you know if/how much you're actually drooping.

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Re: ARP 1601 clone Build Thread

Post by synthcube » Thu Jan 30, 2020 10:13 am

FactoryDefault wrote:
Sun Jan 26, 2020 3:17 pm
sequencer bom update needed on line 46:

Keystone Electronics 5123 PCB COMPACT TEST POINT GRAY .063"

there should be quantity 22 of these. currently that line says quantity 1
good feedback-- we'll amend the BOM of course-- especially for those who love to solder those single point test parts :hihi: :hihi: :hihi:
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Re: ARP 1601 clone Build Thread

Post by solar1 » Thu Jan 30, 2020 10:40 am

elmegil wrote:
Mon Jan 27, 2020 12:47 pm
Yeah, that looks good for TP18. And the TP20 pulses are around 70usec?

What does the voltage look like at pin 3 of Z32 / Z33?

You don't really want to measure the cap directly, because the load of the scope probe can drain the cap. If you want to, use a 10x probe if possible.

Outputs (pin 1) of Z34 & Z35 would also be a good place to measure, that should let you know if/how much you're actually drooping.
since my post, the quantizer output failed completely.
I found my power supply (wall wart) output dropped to about 7.9 vdc, which is under the MeanWell DC-DC module input specs. I replaced the transformer, power rails measure good now, but the quantizer circuit is not operating at all. I am doing further inspection now.

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Re: ARP 1601 clone Build Thread

Post by elmegil » Thu Jan 30, 2020 11:43 am

solar1 wrote:
Thu Jan 30, 2020 10:40 am
since my post, the quantizer output failed completely.
I found my power supply (wall wart) output dropped to about 7.9 vdc, which is under the MeanWell DC-DC module input specs. I replaced the transformer, power rails measure good now, but the quantizer circuit is not operating at all. I am doing further inspection now.
That is the symptom of some marginal part failed and took something with it. Particularly it sounds like it pulled enough current to fault your original wall wart.

#1 thing to inspect right now is what is getting hot. :)

Tracing the circuit/test points again would be the other thing to look at.

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Re: ARP 1601 clone Build Thread

Post by solar1 » Thu Jan 30, 2020 12:22 pm

I have measured z30 as a bit warm at 106F degrees.

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Re: ARP 1601 clone Build Thread

Post by elmegil » Thu Jan 30, 2020 12:24 pm

Do you have spares to try replacing it?

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Re: ARP 1601 clone Build Thread

Post by solar1 » Thu Jan 30, 2020 12:29 pm

no spares at the moment.
a real kicker because I just placed a mouser order a few days ago.

im not going to order a $0.53 part and pay $8+ to ship it.

i'll need to wait until my next order.

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Re: ARP 1601 clone Build Thread

Post by Kipling » Thu Jan 30, 2020 2:43 pm

solar1 wrote:
Thu Jan 30, 2020 12:22 pm
I have measured z30 as a bit warm at 106F degrees.
That would make sense as Z30 (a four pole switch) drives both A and B quantizers directly. Check with the scope for any signal on pins 9 and 10 and if nothing, test pins 6, 8 &12 for any activity, with and without Z30 in place (but note that Z30 has two other poles used elsewhere in the circuit so the sequencer may not run properly without it).

While you're at it, make sure there's no problem with C30 & C31, like any solder bridge or stray wire clipping. They should both be 5nF (5000pF or 0.005uF). R202 and R203 should both be 10k.

Hope this helps.

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Re: ARP 1601 clone Build Thread

Post by solar1 » Thu Jan 30, 2020 3:52 pm

solar1 wrote:
Mon Jan 27, 2020 11:22 am
thanks.

Also, in checking operation, I have found that the start/stop switch is not working. Although I don't have the pedal jack yet connected, I did short the tip to ground and still not working, so I also have a problem there as well.

I found the problem with the start stop switch.....Q10 installed reversed pin layout.
Re installed correctly and start stop switch works now.

Thanks.

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Re: ARP 1601 clone Build Thread

Post by solar1 » Fri Jan 31, 2020 10:02 pm

I found that Z28 was getting super hot. When I pulled it, the board current draw dropped from 540ma to 240ma, and the resistors of Quantizer Chan. A and the Chan cooled right down to normal board temp. Channel A summer circuit cooled way down to normal temp.

I also found Z32 was very hot.

Cannot find any wrong value resistors except R201 was 10K instead of 1K.
Checked C30 & C31...OK
Waiting for replacement ic before proceeding.

After replacing incorrect oriented Q10, Start/ switch stop is working, but now, clock rate slide LED no longer blinks with clock. just stays lit.
All test point waveforms good except TP6 weak signal, but clocking/sequencer A and B outputs work fine.

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Re: ARP 1601 clone Build Thread

Post by Kipling » Sat Feb 01, 2020 5:46 pm

It’s still drawing far too much current. I haven’t measured the 12V DC input current yet (before the dc/dc converter) but I would reckon on 100/150mA. I recall measuring the two 15V power rails which were something like 64mA on the +15V rail and 36mA on the -15V rail.

I’ll look at the schematic ASAP to look for any likely reasons for these ICs to be hot.

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Re: ARP 1601 clone Build Thread

Post by retokid » Sat Feb 01, 2020 6:05 pm

I received my Rev 5 PCB/Panel a couple of days ago, ordered these G-628S-0001 switches from Mouser, and received one of these (the others are backordered).

However, this switch does not fit in the footprint, the spacing of the pins is something like half a mm too big (verticaly). The other similar switch (GF-326-0001) with only two positions fit's perfectly well.

Any thoughts on this ?

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Re: ARP 1601 clone Build Thread

Post by elmegil » Sat Feb 01, 2020 6:16 pm

retokid wrote:
Sat Feb 01, 2020 6:05 pm
I received my Rev 5 PCB/Panel a couple of days ago, ordered these G-628S-0001 switches from Mouser, and received one of these (the others are backordered).

However, this switch does not fit in the footprint, the spacing of the pins is something like half a mm too big (vertically). The other similar switch (GF-326-0001) with only two positions fit's perfectly well.

Any thoughts on this ?
I slightly bent the pins at both ends of the switch inward, and was able to get them to go into the board and fit the switch flush.
IMG_2272.JPG
Be careful pushing it down to the PCB, the inside contacts sometimes will want to bend up instead of having the pin go into the hole, you will need to fix that if/when it happens, and try to bend the pin a little more.

You can see in these photos that the legs just come up and wrap around the base part of the switch:

IMG_2326.JPG
IMG_2327.JPG
You can see on the one where the pin has been jammed in some other way that has caused it to raise up slightly on the inside. You'll want those to be flat before you solder the switches to the PCB.
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Re: ARP 1601 clone Build Thread

Post by Kipling » Sun Feb 02, 2020 9:15 am

Attached is the spec sheet for the CW G-628S-0001 slide switch, giving the pin dimensions and spacings.

If the PCB pad spacing does not match this then it will need altering for future batches. As I didn't create the Rev 5 version and hence don't have the relevant files, I'm unable to alter it myself, though I could recreate it from my Rev 4 files. The only difference between Rev 4 and 5 is the changes of switches which Jammie did.

I would be more inclined to carefully file down the outer pins until it fits snugly in the board, rather than bending them.
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Re: ARP 1601 clone Build Thread

Post by retokid » Sun Feb 02, 2020 10:05 am

elmegil wrote:
Sat Feb 01, 2020 6:16 pm

I slightly bent the pins at both ends of the switch inward, and was able to get them to go into the board and fit the switch flush.
Thanks elmegil for confirming I'm not the only one facing this issue. I was merely incline to cut the topmost pins at the level where they are supposed to touch the PCB and solder the cut pins on the switch side of the PCB. I think the two upper right pins are not even used, so probable only on pin would be left to be soldered on the wrong side (I think 3 of the 4 pins in a row would enter the holes).

I'll post a photo once I'm doing it (but I'll only receive the missing switches in march...).

I am quite surprised not to find any comment on this issue, neither in this thread, neither on Synthcube's site, neither on LED-man's site, feels like nobody in fact tested this board revision.

Synthcube any comments on this ?

Photo for documentation purposes.
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Re: ARP 1601 clone Build Thread

Post by elmegil » Sun Feb 02, 2020 1:52 pm

I only just found this issue about 2 weeks ago, and I pointed it out to Synthcube at the time. Not sure they've had an opportunity to update things yet.

@Kipling good point about filing rather than bending. Would definitely make it less likely to be an issue of care with the contacts.

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Re: ARP 1601 clone Build Thread

Post by Kipling » Sun Feb 02, 2020 2:09 pm

Could someone please accurately measure the pad spacing on the PCB for me? In metric preferably. Cheers.

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Re: ARP 1601 clone Build Thread

Post by elmegil » Sun Feb 02, 2020 4:09 pm

I don't have metric calipers, will this work? I read these as hole - 7mm - hole - 8mm - hole - 7mm - hole
IMG_2336.JPG
IMG_2338.JPG
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Re: ARP 1601 clone Build Thread

Post by elmegil » Sun Feb 02, 2020 4:12 pm

The switches I have appear to be 7.5mm or 7.75mm rather than 7mm between the outer leads and the inner leads.

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Re: ARP 1601 clone Build Thread

Post by Kipling » Sun Feb 02, 2020 4:14 pm

solar1 wrote:
Fri Jan 31, 2020 10:02 pm
I found that Z28 was getting super hot. When I pulled it, the board current draw dropped from 540ma to 240ma, and the resistors of Quantizer Chan. A and the Chan cooled right down to normal board temp. Channel A summer circuit cooled way down to normal temp.

I also found Z32 was very hot.
The only reason I can imagine these ICs are getting very hot is that they are somehow damaged. They are ordinary CMOS logic ICs which should run stone cold normally. They are all very static sensitive so improper handling can damage them.

I know you have mentioned that the power rails seem OK but do they sit at a steady +/- 15V over a period of time? If for example the ground pin of the DC-DC converter wasn't soldered properly (and they take a lot of heat to get a good joint) you may have a floating ground and the power rail voltages could go out of limits for the ICs and damage them.

I've just tested one of my units and it draws 200 - 210mA on the 12V input (before the DC - DC converter). So 240mA on yours is perhaps a little higher than it should be.

Good luck tracking down the faults - I'm sure you'll get there.

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Re: ARP 1601 clone Build Thread

Post by Kipling » Sun Feb 02, 2020 4:23 pm

elmegil wrote:
Sun Feb 02, 2020 4:09 pm
I don't have metric calipers, will this work? I read these as hole - 7mm - hole - 8mm - hole - 7mm - hole
The pad spacing appears to be incorrect. You're showing around 22.5mm between the outer pads when it should be 23.76mm/0.936" (3 x equal spacings of 7.92mm/0.312") from the spec sheet. The two rows should be 8.64mm/0.34" apart.
Capture.JPG
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Re: ARP 1601 clone Build Thread

Post by elmegil » Sun Feb 02, 2020 4:31 pm

Width wise they appear to be 8.5mm side to side; there is no sign of problem with that dimension when inserting the switches. So I would guess the resolution of my ruler/eyes is not sufficient to resolve correctly, and that they likely are the right dimension that way.

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