Batboard

At my local ATC squadron, we have a number of MT6000E hand-held radios. The charger is an NTN1177A, but it's getting wonky (it cuts out after a few moments of charging). What I'd really like to obtain is a copy of the Service Manual for this charger.
The PSU inside the cabinet is an ASTEK AA16330 (pt no. 25R05237R02, delivering 12.5v @10A).

If the fault lies with the PSU, I can find 13.8v at 10 or 20 Amps without trouble.

I do hope someone can help us.

use your volt meter and check the voltage at the powe supply and see if it drops a few volts when it is acting up an test light would work and might be easer to watch to or check and watch the voltage at an battery pack and see if it drops out . i am thinking this is a gang charger with out looking up the model number i have no more input .

Yes, it is a 6-gang charger. I am having trouble understanding the "TTL" line from the main board to the PSU; it is in a very tight spot and thus difficult to get a probe to it.