CHASE GPR4403 Laboratory Receiver Service manual PLEASE (2025 Update)

Op donderdag 25 maart 2010 09:54:35 UTC+1 schreef Dave Bullock:

Dear Dave,

I have exactly the same problem with my Chase receiver, did you manage to fix this problem? Hope to hear from you. Many thanks Jim

Hi guys, Did you ever get your Chase radio working again? Simon

The problem with this units is they loose their Flash Erom memory, causing them to go into Un Calibrated state (Uncal), this is normally due the Main Batteries going Faulty or in a Non Rechargable state, being switcedh off an d un charged for a long period of time, or the unit being taken apart by so meone not realizing if the internal back up battery gets discounted or is f orced flat it will cause eRom loss.

Chase went under years back, there were one or two companies that claimed t hey could fix or re Flash the Roms, but were either unsuccesfull or very ex pensive.

Looks like these threads are years old so this will probably never be read! I designed the receiver. There is no service manual, unless one was done after I left the company. The receiver was calibrated automatically by computer over the rs 232 port before the units were shipped. The calibration points were stored in eprom. Depending on the year of manufacture there was a backup battery or 1 farad cap as backup. As the original spec was 10 years receiver life most receivers have now probably died. The cal software ran on a BBC micro. Any programming info is long gone.

Talk about planned obsolescence!

So the receiver calibration might change over time and there is absolutely no way to fix this as there is no calibration program left anywhere. I/m assuming if anything was changed in the receiver that it would then need calibration...

And people wonder why I like fixing electronic toys prior to the 2000s! Stuff after 2000 is not nearly as fixable - too many one-off or customer parts.

Then there is the question of who owns the device they bought. As an example one brand of pinball games shuts the game down if it is operated on 50 or 60 Hertz and that is different than the line frequency (60/50Hz) that the game was originally set up for.

John :-#(#

This makes me wonder if this end state of calibration data vanishing after xx years was a design requirement (specified by who?) or a byproduct of the design approach taken (to increase machine flexibility? reduce parts count? etc.).

IIRC, EPROMs (i.e. the chips that can be erased with UV light) don't require battery backup. RAM will, though. Why weren't EEPROMs or flash memory used? They would have been available when the things were designed (in the 1990s/early 2000s)... Recently, I picked up one of these radios (GPR4401A) fairly cheaply at a radio rally. A fellow enthusiast in the vicinity remembered using them when working for Motorola, and told me that it was well worth what I paid for it. We discovered that there was still charge in the battery - noise poured from the speaker when the set was switched, on indicating that - at the very least - the demodulator, amp and transducer were functioning. He told me that the charger was connected via the 15-pin D-Sub connector. An odd choice, given that the connector was designed for signals rather than power! Pinouts and charger details would be most welcome (I don't have a manual, and the Wayback Machine gives me the impression that Chase never got round to setting up a website!) The most significant problem, though, is a blank LCD - somewhat inconvenient, as the radio is menu-driven. I gather this wasn't an uncommon issue. Any ideas here, as to a fix? The unavailability of schematics (I doubt they didn't exist, at least internally, for such a complex product) or a service manual didn't help. As regards the possibility of corrupted memory, might it be possible to read the data from the chip (if it's in a set that still works) and stored as a 'backup file'?

At the factory we ran a calibration program. This stepped the receiver every few mega hertz in sync with an accurate sig gen. The receivers internal broadband noise source way turned on every time the receiver was stepped and the resultant receiver output was measured. Any descrepency with the sig gen level at each frequency was stored in rom so it could be added or subtracted to the sig level measurement. I think it is the rom info that gets corrupted over time as the receivers tend to work in all other respects. Bit of a bugger. If I had known people would be using them for home use I would have included a manual cal bypass switch.

It was not a design requirement. The original home office spec was for 10 years operation

Any details, as to the charger requirements and connector pinout, would be most welcome!

Surely, somebody must have the above info?