- crystal replacement alternative in wireless mic? - 8 Updates
- Bose AWRC-1P - 2 Updates
| -faver- <faver10@nospam.net>: Jan 23 12:01PM -0500 I recently pick up a Radio Shack wireless mic at Goodwill for $1. I could hear something in the receiver ratting, so I figured it wouldn't work. I was right. It turns out that the receiver has two crystals: 10.245 Mhz and 39.190 Mhz. The 39.190 Mhz crystal was cleanly broken away from the PCB and making the rattling when moved. Problem is that the break was so close to the case that there's nothing left to solder to, so I need a new crystal. I see one on the "bay" but about $10 by the time shipping and tax are added, which sort of defeats the purpose of a bargain. So, what about this crystal instead? https://www.digikey.com/en/products/detail/abracon-llc/ABLS-13-0625MHZ-10-K4Q-T/2184092 Most likely the native crystal was working from a fundamental overtone anyway. The frequency of the above one gets me close to the frequency needed, but not quite. Assuming this crystal would even work, would a series trimmer cap allow me to adjust to the proper frequency? Thank you. |
| bilou <bilou@sfr.fr>: Jan 24 01:52AM +0100 Le 23/01/2022 à 18:01, -faver- a écrit : > needed, but not quite. Assuming this crystal would even work, would a > series trimmer cap allow me to adjust to the proper frequency? > Thank you. Worth a try IMHO. Think also on the possibility of slightly modifying the 10.245 or the transmitter oscillator. |
| -faver- <faver10@nospam.net>: Jan 23 08:05PM -0500 On 1/23/22 19:52, bilou wrote: > Worth a try IMHO. > Think also on the possibility of slightly modifying the 10.245 or the > transmitter oscillator. Wish there was a schematic somewhere for these. The units themselves are all over the net for sale. Doesn't look like they are the best performers. |
| Phil Allison <pallison49@gmail.com>: Jan 23 05:44PM -0800 -faver- wrote: =============== > Wish there was a schematic somewhere for these. The units themselves > are all over the net for sale. Doesn't look like they are the best > performers. ** So the mic is on 49 MHz - right ? The crystal is an SMD type that just * fell* off the PCB ??? Please explain. .... Phil |
| -faver- <faver10@nospam.net>: Jan 23 09:05PM -0500 On 1/23/22 20:44, Phil Allison wrote: > The crystal is an SMD type that just * fell* off the PCB ??? > Please explain. > .... Phil Yes, 49 Mhz system. The crystal housing is HC-49/U. No, it didn't fall, it looks to me like the leads corroded away right at the PCB. The old yellowed glue is left behind with the imprint of where the crystal was. I've read how corrosive some of these glues could be and I think that's what destroyed the crystal leads. |
| Phil Allison <pallison49@gmail.com>: Jan 23 06:39PM -0800 -faver- wrote: =========== > old yellowed glue is left behind with the imprint of where the crystal > was. I've read how corrosive some of these glues could be and I think > that's what destroyed the crystal leads. ** Absolutely ! Seen the exact thing, many times - in powered loudspeakers made by dB Technologies. Damn "yellow peril" glue ! 4MHz crystals in the DSP system * corroded * right off the PCB and the whole thing stops. Do you have a matching receiver for 49.xxx MHz ? IMO you repair idea sounds unlikely to work out - crystal oscillators are fussy and those models are narrow band, about 25kHz IIRC. Mics on higher bands like 175MHz are often 250KHz wide. FM wireless mics are non simple, but fun to fix. .... Phil |
| -faver- <faver10@nospam.net>: Jan 24 04:35AM -0500 On 1/23/22 21:39, Phil Allison wrote: > Mics on higher bands like 175MHz are often 250KHz wide. > FM wireless mics are non simple, but fun to fix. > .... Phil Well, I do have a radio scanner. That's how I knew that the transmitter at least was working. It seems to be on frequency although, consistent with the reputation I read about these units, the audio frequency range leaves a lot to be desired. I absolutely hate that glue! I have a transceiver that stopped working. On one of the daughter boards inside the unit, most of the electrolytics were glued down with the stuff. I've been in the process of recapping it because about half of the electrolytics are no longer any good. So you don't think using the overtone of the crystal I mentioned will serve as a working substitute for the broken off one? |
| Phil Allison <pallison49@gmail.com>: Jan 24 02:24AM -0800 -faver- wrote: --------------------- < > > Mics on higher bands like 175MHz are often 250KHz wide. > > FM wireless mics are non simple, but fun to fix. > Well, I do have a radio scanner. ** As do I, very handy for such work Long as it can do wide FM up to 1GHz. > at least was working. It seems to be on frequency although, consistent > with the reputation I read about these units, the audio frequency range > leaves a lot to be desired. ** OK, you tricked me with your heading. FYI: A "wireless mic" is a * MICROPHONE * not a receiver. Plus a crystal is way more likely to come to grief in a MIC ! > I absolutely hate that glue! ** Me too, been fighting it for decades. Criminal that many makers keep on using the vile stuff. Roland, Yamaha, Alesis, dB Tech, Rockit and host of others. > So you don't think using the overtone of the crystal I mentioned will > serve as a working substitute for the broken off one? ** Maybe worth a go. But the narrow FM may be your downfall if the frequency is off by even 10kHz. ..... Phil |
| Gavino Geran <gavzgeran@gmail.com>: Jan 24 12:58AM -0800 On Thursday, November 26, 2020 at 7:30:36 AM UTC+8, Cyndi Tiger Dobrinic wrote: |
| Gavino Geran <gavzgeran@gmail.com>: Jan 24 01:05AM -0800 > Did you ever get a schematic because I need one for mine too. > Can you send me one via email pdf > sa...@netease.com Hello Arfa could you please send me also the schematic diagram of bose wave radio Service Manual 260128-0001 Thank you and best regards |
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