Radio Shack Frequency counter model 22-306 gone deaf. - Page 1
Forum section: electronics / repair

author: Lightages
author_rank: Unknown
timestamp: January 12, 2015, 08:37:02 am
content: I seem to remember somewhere on the internet a comment made by someone about the front end amplifier getting fried easily on the 22-306. Mine is basically deaf and I was looking around but found nothing.There is this thread on the forums about another repair:https://www.eevblog.com/forum/repair/radioshack-22-306-frequency-counter-teardown-and-repair/msg155276/#msg155276But it does not relate to my problem. I remember the front end amp transistor being something like MFJ47 or something like that but I am sure I am wrong. Anybody have any schemattics, links, suggestions?

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 12, 2015, 05:04:25 pm
content: Hmm, I have the service manual somewhere.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 12, 2015, 06:02:40 pm
content: Just some quick n dirty camera shots.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 12, 2015, 06:10:57 pm
content: troubleshooting chartI'd go through the basic power supply - reset ckt - oscillator checks first.But the thing uses a center negative barrel connector for external DC and it's not smart enough to tell alkalines from nicads by itself, you have to set a switch.If by "deaf" you mean "no display at all", yes, check the whole power supply section first. One hopes it's not the processor that's fried.

author: Lightages
author_rank: Unknown
timestamp: January 12, 2015, 06:11:23 pm
content: That is very helpful Alex! Thank you.Is there any chance of you scanning the whole document and making it available to me in some form? I am willing to pay a fee.

author: Lightages
author_rank: Unknown
timestamp: January 12, 2015, 06:13:36 pm
content: It is functioning but not displaying stable values and it does not respond to sufficiently large amplitudes as it should.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 12, 2015, 06:58:59 pm
content: Quote from: Lightages on January 12, 2015, 06:11:23 pmI'll think about it, the Canon scanning software is atrocious, I gotta see if I can use something else to stitch together 20 or so scans into a PDF.When you scan a manual, alternate pages are flipped but there's no simple way to tell the stupid software about it.

author: Lightages
author_rank: Unknown
timestamp: January 12, 2015, 10:07:56 pm
content: Don't worry about the order or orientation of anything. If you have the time, just scan to jpgs or whatever. I will sort it out on my end.

author: JoeO
author_rank: Frequent Contributor
timestamp: January 13, 2015, 03:50:44 am
content: How about this?http://www.radioscanner.ru/forum/topic45103.html3rd post down from the top.

author: Lightages
author_rank: Unknown
timestamp: January 13, 2015, 04:16:37 am
content: JoeO:Thanks for the link. I am not sure it is useful though as all the jpg file names reference the 22-305

author: JoeO
author_rank: Frequent Contributor
timestamp: January 13, 2015, 12:14:24 pm
content: Sorry: I put 22-306 into Google search and I never noticed that they listed 22-305 as a result.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 13, 2015, 04:12:25 pm
content: alright alright, I'll try to use the scanner... It's only 24 pages.

author: Lightages
author_rank: Unknown
timestamp: January 13, 2015, 05:14:20 pm
content: I appreciate the effort. Thank you

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 13, 2015, 07:59:27 pm
content: Quote from: Lightages on January 12, 2015, 06:13:36 pmOn what range is that?

author: Lightages
author_rank: Unknown
timestamp: January 14, 2015, 01:03:18 am
content: I don't remember exactly the conditions of the failures. I am sure though that it does not work on the low range.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 14, 2015, 09:17:07 am
content: Quote from: Lightages on January 14, 2015, 01:03:18 amI'm asking because each of the ranges follows a different path:1Hz - 10Mhz: Directly to U31Mhz - 50Mhz: This uses the pre-amp on the top left, then the prescaler U450Mhz - 1.3Ghz: Goes directly to the prescaler U4.So knowing where the problem is would be helpful in finding what's wrong.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 14, 2015, 08:13:42 pm
content: My scanner finally connected again to my wi-fi router. Don't know why Canon makes such opaque, bloated, and bizarre software. "Please wait a while" indeed.I miss my old cheap and cheerful flatbed USB scanner.

author: Lightages
author_rank: Unknown
timestamp: January 16, 2015, 09:18:55 pm
content: Thank you very much to Alex for his help and time with the service manual. It will be very helpful.PAOPBZ, yes I now have a path to follow, thank you.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: January 16, 2015, 10:58:37 pm
content: Quote from: Lightages on January 16, 2015, 09:18:55 pmIt may eventually also show up at BAMA in the Radio Shack section. I am so annoyed at the Canon software that I skipped trying to stitch the schematic pages together.Canon makes one of the worst software suites I've ever seen. Makes Sonic Stage look like iTunes.