Digitech 2112 issue

[Guitarman81]

Hello everybody I've got an issue here with a DigiTech 2112 I'm hoping somebody can point me in the right direction. The unit has been recapped and all capacitors are in their correct locations and polarized correctly. There are no polarized capacitor is in the non-polarized spots. The battery has been replaced and the unit does work partially. The problem I'm experiencing is some of the factory presets work and some do not. It seems it goes in groups. Sometimes one or two will work in a row other times five or six. I'm just not sure where to start on the schematic. Has anyone had this experience? Or perhaps can provide some insight?
I will add that all of the functions will still operate on the presets that do not work, and some of the ones that have no output will show input signal, but only a few.

[g1]

schematics attached.
Also, reset instructions. (pg.2 of resets.pdf)

[Guitarman81]

I have done the factory reset. As I stated above I don't know where to start on the schematic for this issue. Can you point me in the direction of where to start? There's no steady relation to the missing patches. It's not every three it's not every four it's spotted all throughout the precept. How would I go about troubleshooting that on its schematic? And it's not the chip because I have swapped that chip into the DigiTech 2120 and it works just fine. So it's not the name chip itself. The chip that is in the 2112 is the updated 2.11 2120 chip.

[g1]

In the first post you said 'sometimes one or two will work in a row other times five or six'. Is this something that changes at random every time it is powered up, or is it always the same ones that work, and the same that do not work?

[Guitarman81]

It's always the same ones that are out. That does not change. What I meant by what I said was, there's no steady correlation to working and not working. Meaning I may go four or five presets that work, and then two or three or five or six that don't. I don't know exactly how many don't work I just know there are several that do not work throughout the entire preset range. However all the adjustment functions seem to still work, meaning I can change distortion, gain an options like that. It's just it doesn't register any input and there is no output. There are a few however at the higher end of the preset range that I do see registered input signal on the bar graph, but there is no output. But that's only a select few, Maybe four or five total. Everything else has the same issue, no registered input signal and no output.

[g1]

What is the history of the unit? Did it ever work right with the 2120 upgrade eprom?
Have the jumpers been moved to the 256K setting?

[Guitarman81]

I bought this unit and the 2120 as a package from an estate. I do not know the history of the unit, I do know when I received it I plugged it up the back light didn't work, after staying on for 10 minutes it flickered came on and slowly started to build so I figured the electrolytics were going south. Seeing as I did not know how long it had been sitting without use I went ahead and recapped it. There was no issue with the recap job, I triple checked everything to make sure polarity was right, and I have the 2120 as a reference. All of the cap work was good there were no other issues in the unit itself that I can see. So I'm not sure if it ever worked right with the upgrade. The jumpers have been moved to 256. I did not test it before I recapped it unfortunately. I only tested the 2120. I did notice one thing, the 2112 with the 2120 upgrade chip seems to have and 149 or 150 presets I can't remember the exact number but I believe it's 150 presets whereas the 2120 only has a hundred. So I'm not sure how that works considering they both have the same chip. Even with the hard reset the 2112 with the upgraded chip still has the 150 presets. It may be 149 I can't honestly remember as I was trying to figure out why some of the presets were working in some were not. Even above the 100th preset it's still the same problem, some work and some don't.

[g1]

They are exact same revision eprom? What does it say on them (or post pic) ?

edit: early revisions had 100 factory presets, Rev. 2.1 or higher had 141. Aside from this there will be a bank of 'user' presets.

[Guitarman81]

Version 2.11

[g1]

Both units? Has the 2120 with only 100 presets been reset?

[Guitarman81]

I have ordered a new chip off ebay version 2.3. I couldn't find an original 2112 chip anywhere. But I did swap the chips and it worked fine in the 2120. Possibly it may be a software glitch somehow or something. So I ordered the other chip off of eBay. I did not try my 2120s original chip in the 2112 in fear that if something was a foul inside of the 2112 I didn't want it to mess up my 2120 chip.

[g1]

When you boot up the unit it should give the software revision number.
If the 2120 says it has rev. 2.1 or higher, it does not make sense that it would only have 100 presets, it should have 141.
I know this has nothing to do with the 2112 unit, but if you are trying out eproms in the 2120, you want to be sure it is working right. It's possible it was upgraded from a lower rev. and never reset (which is required to complete the upgrade).

[Guitarman81]

Man I'm telling you I reset that thing when I recapped it (2120) as I recapped it also along with the 2112 at the same time, I know I reset it, but I did it again just now and now I have the correct number of presets on the 2120. that's crazy, I know I reset that thing a few times when I swapped those chips over. crazy... anyway I've got the correct number now.

another note on the 2112 I didn't mention earlier. even on the presets that do not work, when I turn up the input gain, I can get the clip light to blink, and it matches my input, so I know it's not just randomly blinking. so, the clip light works for the input as well. just a note. I've got it hooked up now and I'm going to see exactly what presets do not work, not that it'll help, just for my notes. I only use 6 different presets total on these units anyway, had the main 3 I use worked I may have never known it wasn't working correctly. but just my good luck out of 150some presets the 3 main ones that I go to don't work, lol...

[Guitarman81]

here is a list of the ones that do not work. i did notice i had to reset it once during this because it only wanted to see 100 presets. but shows 2120 2.11 on startup. battery has been replaced.
about 74 dont work.
1-9, 13-15, 21-24, 26, 29-30, 34-35, 41-51, 53-54, 56-57, 59-60, 66-71, 73, 75, 77-78, 80-85, 88, 91, 93, 95-96, 101-102, 104-106, 109-112, 115-116, 118-119, 121,123, 127, 129, 131-136, 138-140

[Guitarman81]

Since we seem to have ran out of gas on this post, I actually forgot about it. That's sort of the mo on all the forums unless it's a really simple & common problem, rarely do you find in-depth technical help via forums. So, i wanted to post this follow-up in case someone encounters a similar issue later.
Upon digging deeper into this issue and adjusting all of the different adjustments for each setting that did not work. I noticed that if I put the tube selection in bypass all of the selections that were previously not working would work. The Distortion would also work in bypass or in the on selection. However the tube section would not work in the on position or the off position but only in the bypass position, all other effects for the selected preset Would work and had full adjustments for each. All of the presets that did work ironically enough had the tube setting in the off position in factory setting. So I started checking for B+ on the power tubes. Hindsight of course I should have looked into this first but the issue was a little bit confusing as there were some other issues going on as well I did not mention here not that it would have made a difference.
There are four 10 UF 450 volt capacitors for the B+ filtering in this unit. Two are over near the power switch and the other two are near the 12ax7 tubes. Long story short r266 was open, so the tubes had no B+. So if you experience this problem you may want to check that resistor. It's a surface mount 10K quarter watt resistor. After replacing the resistor everything works as it should. Hopefully this will help somebody at a future time.