Digitech Whammy I WH-1 ROM flashing

[Stevenrb718]

I've been working on a WH-1 recently that didn't function yet seemed to have proper clocks and voltages. I don't have a schematic so I was doing what I could. I had another WH1 come in with separate issues, but the effect functioned after fixing. I took the opportunity to swap some ROMs to see if I could find the issue (I already previously swapped the big IC don't remember the label with no change). Swapping U22 brought the LED back, but no effect, then it seemed to freeze up. Also swapping U10 and U11 seemed to finally bring the pedal back to life. I think I found what these ICs are from blogs: N82S147AN and 27C64. They seem to be pricey, but my question is are they drop-in or do I have to write them? Would it be possible to pull the data from my working ICs and write to replacements? I only have one of those usb programmers that I've used for BIOS chips and a few 16 pin ICs. Any advice/info would be great.

[PRR]

 N82S147AN and 27C64.

Both are (E)PROMs. They are programmable. If you get a  blank, or one programmed for a car-wash, they won't work for you. Yes, geeks used to copy programs to blank ROMs but I think that is rare now?

[hazel44brown]

To fix your WH-1, prioritize backing up the data from your working 27C64 ROMs (U10, U11) using your USB programmer. Verify its compatibility with these chips. The N82S147AN (U22) is harder to replace; your programmer likely won't support it, so explore alternative solutions or specialized PROM programmers. For the 27C64, blank chips can be programmed with your backed-up data. Handle all ICs carefully to avoid static damage.

[paul22]

You Can:
Read the contents of the working 27C64 chips and save them as BIN files using your programmer (if it supports EPROMs).
Write these BIN files to blank 27C64 chips using your programmer.
Read the N82S147AN, if your programmer supports bipolar PROMs (many don't).
You Need To Check:
Does your USB programmer support:
27C64 EPROMs?
N82S147 or 74S147 PROMs? (Many cheap programmers like CH341A don't)
If not, you may need a more capable programmer like:
TL866II Plus (with adapter)
GQ-4X4 (Willem-style)
Data I/O (for industrial PROMs, harder to find)
To Test:
Remove the working U10/U11.
Use your programmer to read and dump the BIN files.
Save and back them up securely.
Try writing them to blank 27C64s.
Swap them into the non-working unit and test.
For U22, due to its OTP nature, you cannot reuse a programmed chip — you'll need a blank compatible PROM and a programmer that supports N82S147 or equivalent (e.g., 74S287, 74S188, etc., depending on the circuit).

[kayocal216]

The ICs you mentioned, N82S147AN (a TTL Bipolar PROM) and 27C64 (a CMOS EPROM), do need programming before use, as blank versions won't function without the appropriate data. You can clone the working ICs by extracting their data using a compatible programmer and transferring it to replacements. Since you already have a USB programmer, ensure it supports these ICs or consider using an adapter. Pay close attention to compatibility factors such as access speed and voltage requirements, as mismatched replacements may not perform correctly in your WH-1 pedal.