Just to give a different option, you could use regular expressions like this:
lcString = [I have some character fields that represent time, for example: 07:00, 08:45, etc]
loRegExp = Createobject('VBScript.RegExp')
with loRegexp as VBScript.RegExp
.IgnoreCase = .T.
.Global = .T.
.Multiline = .T.
.Pattern = '(\d\d):(\d\d)'
lcNewText = .Replace(lcString, '$1$2')
endwith
? lcNewTextNotice that I edited a little bit your message so it has a colon that is not part of the time, that would be changed by strtran but it is not changed by the regular expression, that is why I showed this alternative, which might be irrelevant in your case.
PS
An even better solution would be to set the pattern to valid hours.
"The five senses obstruct or deform the apprehension of reality."
Jorge L. Borges?
"Premature optimization is the root of all evil in programming."
Donald Knuth, repeating C. A. R. Hoare
"To die for a religion is easier than to live it absolutely"
Jorge L. Borges
